Thursday, March 29, 2012
Tuesday, March 20, 2012
PROFESSIONAL PRACTICE
FIVE METHODS OF COMPENSATION
% OF CONSTRUCTION COST.
MULTIPLE OF DIRECT PERSONNAL EXPENSES
PROFESSIONAL FEE + EXPENSES
LUMP SUM OR FIXED FEE
PER DIEM + REIMBURSIBLE EXPENSE
PROJECT CLASSIFICATION
GROUP 1 = Simplest, min. fin, structural, etc. (50 million & less = 6%)
Armories, Bakeries, Freight, Parking, Market, Warehouse
GROUP 2 = Moderate complexity, (50 million & less = 7 %)
Banks, City Halls, School, Mall, Motel, Apartment, Office Bldg
GROUP 3 = Exceptional char., large amount Structural, etc. (50 million & less = 8%)
Atomic Fac., Airport, Gym, Lab., Hotels. Hospital, Breweries,
GROUP 4 = Residence (Single Det & Duplex) (10 % of Proj. Const. Cost)
GROUP 5 = Monumental Bldg. (12 % of Proj Const. Cost)
Expo, Mausoleum, Museums
GROUP 6 = Repetitive Const. of Bldgs
1st Structure = Min. Basic fee
2nd Structure = 80 % of Basic F
3rd Structure = 60 % of Basic F
Succeding = 40 % of Basic F
GROUP 7 = Housing Projects (Several Res. Units on a Single Site)
1st Unit = 10 % of Proj. Const.Cost as BASIC FEE
2-10 Units = 1 unit + 60% of 1st Unit (Basic F)
11 & above = 10 units + 30% of 1st Unit (Basic F)
GROUP 8 = Interior & Landscaping Design (Extensive detailing)
Min Basic fee = 15% of Project Const Cost
GROUP 9 = for Alterations & Additions of Existing Bldgs
50% of the total of 150% of the Basic Fee
GROUP 10 = Consultation and Arbitrations
Architects Services & Compensations
UAP DOC 201 PRE – DESIGN SERVICES
- Compensated on the basis of MULIPLE OF DIRECT PERSONNEL EXPENSE – 2 - 2.5
- Compensated for every technical hour
- Progress Payment
UAP DOC 202 DESIGN SERVICES
Upon Signing of Agreement = 5%
Upon Completion of Schemes (not >15 days) = 15%
Upon completion of Design Devt. = 35%
Upon Completion of Contract Documents = 85%
After Awarding of contracts = 85%
Balance = upon completion of Const Work
Work Suspended or Abandoned
The remaining 15% of his work to be paid by owner is:
10% - Arch. Liability under the civil code
5% - construction Services
UAP DOC 203 SPECIALIZED ALLIED SERVICES
Payment Schedule:
1. Upon Submission of preliminary design = 30 % of the fee
2. Upon Submission of Final design = 50%
3. Upon completion of he project = 20%
INTERIOR DESIGN SERVICES
Architects fee = 15% but it can be range 12% -20%
Consultants Fee = 5 %
ACOUSTICS, ECE SERVICES and LANDSCAPE DESIGN SERVICES
Architects fee = 10% - 15% Consultants Fee = 5 %
PHYSICAL PLANNING
TYPE 1 = 50 HEC or less = 5,000 / hec
TYPE 2 = 100 HEC or less = 3.000 / hec
TYPE 3 = 100 HEC or less = 2,000 / hec.
*the above stipulated rate is for moderately flat land
If the land is rugged w/ steep terrain the fee shall inc. 30 %
Environmental Planner – Concerned w/ the management & use of lands/conservation
Fees = Physical Planning Prof. Fess + expenses
UAP DOC 204 CONSTRUCTION SERVICES
Quality Control of Work, Evaluation & Const. Work, Keeping of Records, Reports & Contracts Doc.,
Architects as FULL TIME SUPERVISOR = 1% - 1 ½ % of Const Cost
Architects as CONSTRUCTION MANAGER = 1 ½ % - 3 % of Const Cost
-coordination & supervision, cost & time control, quality control of work.
UAP DOC 205 POST - CONSTRUCTION SERVICES
Bldg & Equipment Maintenance, Bldg & Ground Admin., Post –Construction Evaluation
Compensation = Salary Basis (fixed monthly/daily)
or Management fee ( 4 % - 6 % gross rentals)
UAP DOC 206 COMPREHENSIVE ARCHITECTURAL SERVICES
Scope: Pre- Design to Post Construction Services
Project Manager = (2 % - 5 % of Estimated Project Cost)
-Coordinates the whole range of Comprehensive arch.
UAP DOC 207 DESIGN- BUILD SERVICES
Architects is liable of both design & Construction
TYPES:
1. Design- Build Services by Administration = 7% + Architects fee on Regular D Services
2. Design – Build Services on a Guaranteed Maximum Cost = 10% + Architects fee on RDS
3. Design – Build Service on Lump Sum Contract
UAP DOC 208 SELECTION OF ARCHITECTS
UAP DOC 209 COMPETITION CODE
UAP DOC 301 GENERAL CONDITIONS
UAP DOC 307 PRACTICAL SPECIFICATIONS WRITING
UAP DOC 200 CODE OF ETHICAL CONDUCT
PP – UAP DOC. 211 (RA 545, PD 223, LOI 1000) – Prof. Regulatory Laws Governing the Practice of Architecture
RA 545 – an act to regulate the practice of architecture in the Philippines.
PD 223 – Creating the professional regulation commission and prescribing its powers & functions.
LOI 1000 – Letter of Instruction
PD 1096 National Building Code.
BP 344 An act to enhance The mobility of disabled persons.
PD 1185 Fire Code of the Philippines
RA 386 Civil Codes of the Philippines
(Contracts and Obligations)
PD 957 Subdivision Law
BP 220 Zoning Regulations
PD 856 Sanitation Code of the Philippines
% OF CONSTRUCTION COST.
MULTIPLE OF DIRECT PERSONNAL EXPENSES
PROFESSIONAL FEE + EXPENSES
LUMP SUM OR FIXED FEE
PER DIEM + REIMBURSIBLE EXPENSE
PROJECT CLASSIFICATION
GROUP 1 = Simplest, min. fin, structural, etc. (50 million & less = 6%)
Armories, Bakeries, Freight, Parking, Market, Warehouse
GROUP 2 = Moderate complexity, (50 million & less = 7 %)
Banks, City Halls, School, Mall, Motel, Apartment, Office Bldg
GROUP 3 = Exceptional char., large amount Structural, etc. (50 million & less = 8%)
Atomic Fac., Airport, Gym, Lab., Hotels. Hospital, Breweries,
GROUP 4 = Residence (Single Det & Duplex) (10 % of Proj. Const. Cost)
GROUP 5 = Monumental Bldg. (12 % of Proj Const. Cost)
Expo, Mausoleum, Museums
GROUP 6 = Repetitive Const. of Bldgs
1st Structure = Min. Basic fee
2nd Structure = 80 % of Basic F
3rd Structure = 60 % of Basic F
Succeding = 40 % of Basic F
GROUP 7 = Housing Projects (Several Res. Units on a Single Site)
1st Unit = 10 % of Proj. Const.Cost as BASIC FEE
2-10 Units = 1 unit + 60% of 1st Unit (Basic F)
11 & above = 10 units + 30% of 1st Unit (Basic F)
GROUP 8 = Interior & Landscaping Design (Extensive detailing)
Min Basic fee = 15% of Project Const Cost
GROUP 9 = for Alterations & Additions of Existing Bldgs
50% of the total of 150% of the Basic Fee
GROUP 10 = Consultation and Arbitrations
Architects Services & Compensations
UAP DOC 201 PRE – DESIGN SERVICES
- Compensated on the basis of MULIPLE OF DIRECT PERSONNEL EXPENSE – 2 - 2.5
- Compensated for every technical hour
- Progress Payment
UAP DOC 202 DESIGN SERVICES
Upon Signing of Agreement = 5%
Upon Completion of Schemes (not >15 days) = 15%
Upon completion of Design Devt. = 35%
Upon Completion of Contract Documents = 85%
After Awarding of contracts = 85%
Balance = upon completion of Const Work
Work Suspended or Abandoned
The remaining 15% of his work to be paid by owner is:
10% - Arch. Liability under the civil code
5% - construction Services
UAP DOC 203 SPECIALIZED ALLIED SERVICES
Payment Schedule:
1. Upon Submission of preliminary design = 30 % of the fee
2. Upon Submission of Final design = 50%
3. Upon completion of he project = 20%
INTERIOR DESIGN SERVICES
Architects fee = 15% but it can be range 12% -20%
Consultants Fee = 5 %
ACOUSTICS, ECE SERVICES and LANDSCAPE DESIGN SERVICES
Architects fee = 10% - 15% Consultants Fee = 5 %
PHYSICAL PLANNING
TYPE 1 = 50 HEC or less = 5,000 / hec
TYPE 2 = 100 HEC or less = 3.000 / hec
TYPE 3 = 100 HEC or less = 2,000 / hec.
*the above stipulated rate is for moderately flat land
If the land is rugged w/ steep terrain the fee shall inc. 30 %
Environmental Planner – Concerned w/ the management & use of lands/conservation
Fees = Physical Planning Prof. Fess + expenses
UAP DOC 204 CONSTRUCTION SERVICES
Quality Control of Work, Evaluation & Const. Work, Keeping of Records, Reports & Contracts Doc.,
Architects as FULL TIME SUPERVISOR = 1% - 1 ½ % of Const Cost
Architects as CONSTRUCTION MANAGER = 1 ½ % - 3 % of Const Cost
-coordination & supervision, cost & time control, quality control of work.
UAP DOC 205 POST - CONSTRUCTION SERVICES
Bldg & Equipment Maintenance, Bldg & Ground Admin., Post –Construction Evaluation
Compensation = Salary Basis (fixed monthly/daily)
or Management fee ( 4 % - 6 % gross rentals)
UAP DOC 206 COMPREHENSIVE ARCHITECTURAL SERVICES
Scope: Pre- Design to Post Construction Services
Project Manager = (2 % - 5 % of Estimated Project Cost)
-Coordinates the whole range of Comprehensive arch.
UAP DOC 207 DESIGN- BUILD SERVICES
Architects is liable of both design & Construction
TYPES:
1. Design- Build Services by Administration = 7% + Architects fee on Regular D Services
2. Design – Build Services on a Guaranteed Maximum Cost = 10% + Architects fee on RDS
3. Design – Build Service on Lump Sum Contract
UAP DOC 208 SELECTION OF ARCHITECTS
UAP DOC 209 COMPETITION CODE
UAP DOC 301 GENERAL CONDITIONS
UAP DOC 307 PRACTICAL SPECIFICATIONS WRITING
UAP DOC 200 CODE OF ETHICAL CONDUCT
PP – UAP DOC. 211 (RA 545, PD 223, LOI 1000) – Prof. Regulatory Laws Governing the Practice of Architecture
RA 545 – an act to regulate the practice of architecture in the Philippines.
PD 223 – Creating the professional regulation commission and prescribing its powers & functions.
LOI 1000 – Letter of Instruction
PD 1096 National Building Code.
BP 344 An act to enhance The mobility of disabled persons.
PD 1185 Fire Code of the Philippines
RA 386 Civil Codes of the Philippines
(Contracts and Obligations)
PD 957 Subdivision Law
BP 220 Zoning Regulations
PD 856 Sanitation Code of the Philippines
WASTE PIPE SIZES
WASTE PIPE SIZES
SINK WASTE 38mm. (1-1/2)
50mm. (2’’)
SLOP SINK 75 ( 3’’ ) - 100mm.
SCULLERY SINK 50mm
PANTRY SINK 38mm
FACTORY SINK 50mm
BATHTUB 38 – 50mm.
LAVATORIES 50mm
SHOWER BATH 50mm
URINAL 50mm
LAUNDRY 38 - 50mm
DRINKING FOUNTAIN 32mm
LAVATORY 50mm
HOSPITAL FIX. 50mm
SINK WASTE 38mm. (1-1/2)
50mm. (2’’)
SLOP SINK 75 ( 3’’ ) - 100mm.
SCULLERY SINK 50mm
PANTRY SINK 38mm
FACTORY SINK 50mm
BATHTUB 38 – 50mm.
LAVATORIES 50mm
SHOWER BATH 50mm
URINAL 50mm
LAUNDRY 38 - 50mm
DRINKING FOUNTAIN 32mm
LAVATORY 50mm
HOSPITAL FIX. 50mm
CONSTRUCTION TERMS (english-filipino)
1. POSTE - HALIGE
2. GUILILAN - GIRDER
3. SULERAS - JOIST
4. SAHIG, SUELO - FLOORING
5. SEPO - GIRT
6. BIGA - BEAM
7. BARAKILAN - BOTTOM CHORD
8. REOSTRA - PURLIN
9. SENEPA - FASCIA BOARD
10. KOSTILYAHE - CEILING JOIST
11. TABIKE - SIDING (EXTERNAL)
12. PILARETE - STUD (VERTICAL)
13. PABALAGBAG - STUD (HORIZONTAL)
14. PASAMANO - WINDOW SILL
15. SUMBRERO - WINDOW HEAD
16. HAMBA - WINDOW JAMB / DOOR JAMB
17. SINTURON - COLLAR PLATE
18. HARDINERA - STRINGER (OPEN)
19. MADRE (de escalera) - STRINGER (CLOSED)
20. BAYTANG - TREAD
21. TAKIP (SILIPAN) - RISER
22. GABAY - HANDRAIL
23. MULDURA - MOULDING
24. SIBE - EAVE
25. BOLADA - PROJECTION
26. BALANGKAS - FRAME WORK
27. KANAL - GUTTER
28. ALULOD - CONDUCTOR
29. PLANCHUELA - W. I. STRAP
30. PIERNO - BOLT
31. PLANCHA - SCAFFOLDING
32. ESTAKA - STAKE
33. KUSTURADA - PLASTERED COURSE
34. PALITADA - STUCCO OR PLASTER
35. REBOCADA - SCRATCH COAT
36. PIKETA - PICKWORK (on masonry)
37. MONYEKA - VARNISH FINISH
38. BIENTO - SPACING OF GAP
39. LARGA MASA - CONCRETE SLAB (rough)
40. ASINTADA - ALIGNMENT
41. HULOG - PLUMB LINE
42. BALDOSA - CEMENT TILE
43. LADRILYO - CEMENT BRICK
44. BATIDORA - DOOR FILLET
45. KANAL - GROOVE
46. HASPE - GOOD GRAIN
47. PLANTILYA - PATTERN / SCHEDULE
48. BISAGRA - HINGE
49. DE BANDEHA - PANELED DOOR
50. ESCOMBRO - EARTHFILL
51. LASTILYAS - MASONRY FILL
52. LIYABE - ADOBE ANCHOR
53. HINANG - SOLDER
54. ESTANYO - NICOLITE BAR
55. SUBAN, SUBUHAL - TEMPER (metal work)
56. PIE DE GALLO - DIAGONAL BRACE
57. PUNSOL - NAIL SETTER
58. POLEYA - WIRING KNOB
59. ESPOLON - CABINET HINGE
2. GUILILAN - GIRDER
3. SULERAS - JOIST
4. SAHIG, SUELO - FLOORING
5. SEPO - GIRT
6. BIGA - BEAM
7. BARAKILAN - BOTTOM CHORD
8. REOSTRA - PURLIN
9. SENEPA - FASCIA BOARD
10. KOSTILYAHE - CEILING JOIST
11. TABIKE - SIDING (EXTERNAL)
12. PILARETE - STUD (VERTICAL)
13. PABALAGBAG - STUD (HORIZONTAL)
14. PASAMANO - WINDOW SILL
15. SUMBRERO - WINDOW HEAD
16. HAMBA - WINDOW JAMB / DOOR JAMB
17. SINTURON - COLLAR PLATE
18. HARDINERA - STRINGER (OPEN)
19. MADRE (de escalera) - STRINGER (CLOSED)
20. BAYTANG - TREAD
21. TAKIP (SILIPAN) - RISER
22. GABAY - HANDRAIL
23. MULDURA - MOULDING
24. SIBE - EAVE
25. BOLADA - PROJECTION
26. BALANGKAS - FRAME WORK
27. KANAL - GUTTER
28. ALULOD - CONDUCTOR
29. PLANCHUELA - W. I. STRAP
30. PIERNO - BOLT
31. PLANCHA - SCAFFOLDING
32. ESTAKA - STAKE
33. KUSTURADA - PLASTERED COURSE
34. PALITADA - STUCCO OR PLASTER
35. REBOCADA - SCRATCH COAT
36. PIKETA - PICKWORK (on masonry)
37. MONYEKA - VARNISH FINISH
38. BIENTO - SPACING OF GAP
39. LARGA MASA - CONCRETE SLAB (rough)
40. ASINTADA - ALIGNMENT
41. HULOG - PLUMB LINE
42. BALDOSA - CEMENT TILE
43. LADRILYO - CEMENT BRICK
44. BATIDORA - DOOR FILLET
45. KANAL - GROOVE
46. HASPE - GOOD GRAIN
47. PLANTILYA - PATTERN / SCHEDULE
48. BISAGRA - HINGE
49. DE BANDEHA - PANELED DOOR
50. ESCOMBRO - EARTHFILL
51. LASTILYAS - MASONRY FILL
52. LIYABE - ADOBE ANCHOR
53. HINANG - SOLDER
54. ESTANYO - NICOLITE BAR
55. SUBAN, SUBUHAL - TEMPER (metal work)
56. PIE DE GALLO - DIAGONAL BRACE
57. PUNSOL - NAIL SETTER
58. POLEYA - WIRING KNOB
59. ESPOLON - CABINET HINGE
STRUCTURAL
STRUCTURAL
Zoning, site characteristics, occupancy, configuring structural system and height
The procedures and limitations for the design of structures shall be determined by the following factors.
14
Minimum number of stories recommended to be provided with at least 3 approved recording accelerographs.
Owner
Maintenance and service of accelorographs shall be provided by the ___
Occupant o the building
Who shall be responsible for keeping the actual live load below the allowable limits and shall be liable for any failure on the structure due to overloading
Load duration
The period of continuous application of a given load or the aggregate of periods of intermittent application of the same load
14 sq. m
Minimum area in square meters a member supports which the design live load may be reduced
1.50 sq. m
Minimum height of any wall requiring structural design to resist loads onto which they are subjected
1/240 of wall span
Maximum deflection of a brittle finished wall subjected to a load of 250 Pascal applied. Perpendicular to said wall
1/120 of wall span
Maximum deflection of flexible finished wall subjected to a load of 250 Pascal applied perpendicular to said wall
60 sq. m
Maximum floor area for a low-cost housing unit
Base
The level at which the earthquake motions are considered to be imparted to the structure of the level at which the structure as a dynamic vibrator is supported
Collector
A member or an element provided to transfer lateral forces from a portion of a structure to vertical elements of the lateral force resisting system
Diaphragm
A horizontal or nearly horizontal system acting to transmit lateral forces to the vertical resisting elements it includes horizontal bracing system
Base Shear V
The total designed lateral force or shear at the base of a structure
Boundary element
An element at edge of opening or at perimeters of shear walls or diaphragm
Brace Frame
An essentially vertical truss system of the concentric or accentric type which is provided to resist lateral forces
Building Frame System
A essentially complete space frame which provides supports for gravity loads
Dual System
A combination of a Special or Intermediate Moment Resisting Space Frame and Shear Walls or Braced Frame
Eccentric Brace Frame (EBF)
The form of braced frame where at least one end of each brace intersects a beam at a point away from the column girder joint
Joints
The entire assemblage at the Intersection of the members
Girder
The horizontal member in a frame system, a beam
-the major horizontal supporting member of the floor system
Diaphragm Strut
An element of a diaphragm parallel to the applied load, which collects and transfers diaphragm shear to vertical resisting elements of distributes loads within the diaphragm. Such members may take axial tension or compression
Diaphragm Chord
The boundary element of a diaphragm or a shear wall which is assumed to take axial stresses analogous to the flanges of a beam
Essential facilities
Those structures which are necessary for emergency post earthquake operations
Lateral Force Resisting System
That part of the structural system assigned to resist lateral forces
Ordinary Moment Resisting Space Frame
Moment resisting space frame not meeting special detailing requirements for ductile behavior
Story Drift
The displacement of one level relative to the level above or below
Strength
The usable capacity of a structure or its members to resist loads within the deformation limits prescribed in this document
Platform
The lower rigid portion of a structure having a vertical combination of structural system
Horizontal Bracing system
Horizontal truss system that serves the same function as a diaphragm
Structure
An assemblage of framing members designed to support gravity loads and resist lateral forces
Bearing Wall System
A structural system without complete vertical load carrying space frame. This system provides support for gravity loads. Resistance to lateral load is provided by shear walls or braced frames
Building Frame system
A structural system with essentially complete space frame providing support for gravity loads. Resistance to lateral load is provided by shear walls or braced frames
Moment Resisting Frame System
A structural system with an essentially complete space frame providing support for gravity loads. Moments resisting space frames provide resistance to lateral load primarily by flexural action of members.
Weak story
Is one in which the story strength is less than 80% of that the story above
Time History Analysis
An elastic or inelastic dynamic analysis in which a mathematical model of the structure is subjected to a ground motion time history. The structures time dependant dynamic response to these motion is obtained through numerical integration of its equations of motions.
Orthogonal Effect
The effect on the structure due to earthquake motions acting in directions other than parallel to the direction of resistance under consideration
P-delta effect
The secondary effect on shears and moments of frame members induced by the vertical loads acting on the laterally displaced building frame
Admixture
Material other than water aggregate or hydraulic cement used as an ingredient of concrete and added to concrete before or during its mixing to modify its properties
Plain Concrete
Concrete that doesn’t not conform to definition of reinforced concrete
Pedestal
Upright compression member with a ratio of unsupported height to average least lateral dimension of less than three (3 m)
Modulus of Elasticity
Ratio of normal stress to corresponding strain for tensile or compressive stresses below proportional limit of material
-in the formula e=PL/AE, E stands for ___
Jacking Force
In prestressed concrete, temporary force exerted by device that introduces tension into prestressing tendons
Embedment Length
Length of embedded reinforcement provided beyond a critical section
Effective Prestress
Stress remaining in prestressing tendons after all losses have occurred, excluding effects of dead load and superimposed loads
Development Length
Length of embedded reinforcement required to develop the design strength of reinforcement at a critical section
Curvature friction
Friction resulting from bends or curves in the specified prestressing tendon profile
Structural Lightweight Concrete
Concrete containing lightweight aggregate
Bonded tendon
Prestressing tendon that is bonded to concrete either directly or through grouting
Structural Steel
ASTM A36
ASTM A514
High Yield Strength Quenched and Tempered Alloy Steel Plate, Suitable for Welding
TRUE
True or False, bar larger than 32mm in diameter shall not be bundled in beams
40 mm
Minimum concrete cover for a Prestressed concrete for beams and columns for primary reinforcement
Poisson’s Ratio
In a material under tension or compression, the absolute value of the ratio transverse strain to the corresponding longitudinal strain
Slenderness Ratio
In column, the ratio of its effective length to its least radius of gyration
Torsion
A quantity which measures the resistance of the mass to being revolved about a line
Flat slab
A type of concrete floor which has no beam
Shear
The tendency for one part of a beam to move vertically with respect to an adjacent part
Deformation
A change in shape of a material when subjected to the action of force
Yielding Stress
The maximum value of tension, compression, or shear respectively the material sustain without failure
Stress
-It means that by which a body develops internal resistance to stress
-Intensity of force per unit area
Allowable Stress
The greatest stress which a material is capable of developing without permanent deformation remaining upon the complete release of stress
Tie / Stirrup
Loop of reinforcing bar or wire enclosing longitudinal reinforcement
Stiffness Ration
The measure of stiffness of a material
Punching Shear
The failure in a base when a heavily loaded column strikes hole through it
Deflection
The deformation of a structural member as a result of loads acting on it
6 inches
Nominal thickness of a timber
Equilibrium
The sum of forces in the orthogonal directions and the sum of all moments about any points are zero
2 years
The complete records of tests conducted (slump, compression test, etc.) shall be preserved and made available for inspection during the progress of construction and after completion of the project for a period of not less than ___
Not less than 1”x4”
Wood board should have a thickness specification
Run
The distance from the first to the last riser of a stair flight
Portable Hand router
A high-speed rotary shaping hand power tool used to make smooth cutting and curving on solid wood
Knots
Wood defects are: heart shake, cup shake, star shake and ___
Smoothed and planed lumber
Dressed lumber is referred to ___
Live load
It refers to the occupancy load which is either partially or fully in place or may not be present at all
Cross cut saw
The other kind of handsaw other than rip cut saw
Effective Length
The distance between inflection points in the column when it breaks
Volume
The amount of space measured in cubic units
Contraction Joint
An expansion joint of adjacent parts of a structure to permit expected movements between them
Total Run
The total of all tread widths in a stair
Bond stress
The force adhesion per unit area of contact between two bonded surfaces
Purlin
A structural member spanning from truss to truss or supporting a rafter
Size of dead load deflection
Size of camber for a 25 meters steel truss
Shear connector
A connector such as a welded strut, spiral bar, or short length of channel which resists horizontal shear between elements
Shear Stress (Shearing Stress)
The force per unit area of cross section which tend to produce shear
Hook’s Law
The law that relates the linear relationship between stresses and strain
4 x diameter of bolt
Minimum spacing of bolts in timber connection measured from center of bolts parallel for parallel to grain loading is equal to ___
4 x diameter of bolt
According to the provision of the NSCP on timber connection and fastening the loaded edge distance for perpendicular to grain loading shall be at least
2.5
NSCP specifies spacing between rows of bolts for perpendicular to grain loading shall be at least ___ times bolt diameter for L/d ratio of 2
12 mm
Minimum diameter of bolts to be used in timber connections and fastening in accordance with NSCP specifications
50
Simple solid timber columns have slenderness ratio not exceeding ___
11 diameters
Nails and spikes for which the wire gauges or lengths not set forth in the NSCP specifications shall have a required penetration of not less than __
1/6 depth of member
Notches in sawn lumber bending members in accordance with the NSCP specifications shall not exceed
Middle third span
Notches in sawn lumber shall not be located in the
¼ the depth
Notches in the top and bottom of joist shall not exceed
.60 of specified yield strength
Allowable stresses for tension in structural steel in terms of gross area
.50 of specified minimum tensile strength
Allowable tensile stress of structural steel based on effective area
0.45 Fy
Allowable stress for tension on pin connected members based on net area
0.40 Fy
Allowable shear stress on structural steel on the cross sectional area effective in resisting shear
100%
For structures carrying live loads which induce impact, the assumed live load shall be increased sufficiently to provide for same, for supports of elevators the increase shall be
200
The slenderness ratio of compression members shall not exceed ___
240
The slenderness ratio main members in tension shall not exceed ___
40 mm
Concrete cover for pipes, conduits, and fittings shall not be less than ___ for concrete exposed to earth or weather
20 mm
Concrete cover for pipes, conduits, and fittings shall not be less than ___ for concrete not exposed to earth or weather
7 days
Curing of concrete (other than high-early strength) shall be maintained above 10 C and in moist condition for at least the first ___ days after placement
7 days
If concrete in structure will dry under service conditions, cores shall be air-dried for ___ days before test and shall be tested dry.
3 days
Cutting for high early strength concrete shall be maintained above 10 C and in moist condition for at least the ___days after placement
25 mm
The minimum clear spacing between parallel bars in layer shall be db (diameter of bar) but not less than ___
180 deg. Bend +4db extension but not less than 65 mm at the end of bar
Standard hooks used in reinforced concrete beam shall mean
90 deg. Bend + 6db extension at free end
Standard hooks for stirrups and tie hooks 16mm bar and smaller
90 deg. Bend + 12db extension at free end
Standard hooks for stirrups and thie hooks 20-25 mm bar
-12 mm
Allowable tolerance on minimum concrete cover for depth greater than 200 mm
+-50 mm
Allowable tolerance for longitudinal location of bends and ends of reinforcement
40 db
Individual bars with a bundle terminated within the span of flexural members shall terminate at different points with a stagger of at least
3 db
Clear distance between pre-tensioning tendons at each end of member shall not be less than ___ for strands
4 db
Clear distance between pre-tensioning tendons at each of member shall to be less than ___ for wire
75 mm
Minimum concrete cover provided for reinforcement of cast in place against permanently exposed earth or weather using bars larger than 36 mm
Zoning, site characteristics, occupancy, configuring structural system and height
The procedures and limitations for the design of structures shall be determined by the following factors.
14
Minimum number of stories recommended to be provided with at least 3 approved recording accelerographs.
Owner
Maintenance and service of accelorographs shall be provided by the ___
Occupant o the building
Who shall be responsible for keeping the actual live load below the allowable limits and shall be liable for any failure on the structure due to overloading
Load duration
The period of continuous application of a given load or the aggregate of periods of intermittent application of the same load
14 sq. m
Minimum area in square meters a member supports which the design live load may be reduced
1.50 sq. m
Minimum height of any wall requiring structural design to resist loads onto which they are subjected
1/240 of wall span
Maximum deflection of a brittle finished wall subjected to a load of 250 Pascal applied. Perpendicular to said wall
1/120 of wall span
Maximum deflection of flexible finished wall subjected to a load of 250 Pascal applied perpendicular to said wall
60 sq. m
Maximum floor area for a low-cost housing unit
Base
The level at which the earthquake motions are considered to be imparted to the structure of the level at which the structure as a dynamic vibrator is supported
Collector
A member or an element provided to transfer lateral forces from a portion of a structure to vertical elements of the lateral force resisting system
Diaphragm
A horizontal or nearly horizontal system acting to transmit lateral forces to the vertical resisting elements it includes horizontal bracing system
Base Shear V
The total designed lateral force or shear at the base of a structure
Boundary element
An element at edge of opening or at perimeters of shear walls or diaphragm
Brace Frame
An essentially vertical truss system of the concentric or accentric type which is provided to resist lateral forces
Building Frame System
A essentially complete space frame which provides supports for gravity loads
Dual System
A combination of a Special or Intermediate Moment Resisting Space Frame and Shear Walls or Braced Frame
Eccentric Brace Frame (EBF)
The form of braced frame where at least one end of each brace intersects a beam at a point away from the column girder joint
Joints
The entire assemblage at the Intersection of the members
Girder
The horizontal member in a frame system, a beam
-the major horizontal supporting member of the floor system
Diaphragm Strut
An element of a diaphragm parallel to the applied load, which collects and transfers diaphragm shear to vertical resisting elements of distributes loads within the diaphragm. Such members may take axial tension or compression
Diaphragm Chord
The boundary element of a diaphragm or a shear wall which is assumed to take axial stresses analogous to the flanges of a beam
Essential facilities
Those structures which are necessary for emergency post earthquake operations
Lateral Force Resisting System
That part of the structural system assigned to resist lateral forces
Ordinary Moment Resisting Space Frame
Moment resisting space frame not meeting special detailing requirements for ductile behavior
Story Drift
The displacement of one level relative to the level above or below
Strength
The usable capacity of a structure or its members to resist loads within the deformation limits prescribed in this document
Platform
The lower rigid portion of a structure having a vertical combination of structural system
Horizontal Bracing system
Horizontal truss system that serves the same function as a diaphragm
Structure
An assemblage of framing members designed to support gravity loads and resist lateral forces
Bearing Wall System
A structural system without complete vertical load carrying space frame. This system provides support for gravity loads. Resistance to lateral load is provided by shear walls or braced frames
Building Frame system
A structural system with essentially complete space frame providing support for gravity loads. Resistance to lateral load is provided by shear walls or braced frames
Moment Resisting Frame System
A structural system with an essentially complete space frame providing support for gravity loads. Moments resisting space frames provide resistance to lateral load primarily by flexural action of members.
Weak story
Is one in which the story strength is less than 80% of that the story above
Time History Analysis
An elastic or inelastic dynamic analysis in which a mathematical model of the structure is subjected to a ground motion time history. The structures time dependant dynamic response to these motion is obtained through numerical integration of its equations of motions.
Orthogonal Effect
The effect on the structure due to earthquake motions acting in directions other than parallel to the direction of resistance under consideration
P-delta effect
The secondary effect on shears and moments of frame members induced by the vertical loads acting on the laterally displaced building frame
Admixture
Material other than water aggregate or hydraulic cement used as an ingredient of concrete and added to concrete before or during its mixing to modify its properties
Plain Concrete
Concrete that doesn’t not conform to definition of reinforced concrete
Pedestal
Upright compression member with a ratio of unsupported height to average least lateral dimension of less than three (3 m)
Modulus of Elasticity
Ratio of normal stress to corresponding strain for tensile or compressive stresses below proportional limit of material
-in the formula e=PL/AE, E stands for ___
Jacking Force
In prestressed concrete, temporary force exerted by device that introduces tension into prestressing tendons
Embedment Length
Length of embedded reinforcement provided beyond a critical section
Effective Prestress
Stress remaining in prestressing tendons after all losses have occurred, excluding effects of dead load and superimposed loads
Development Length
Length of embedded reinforcement required to develop the design strength of reinforcement at a critical section
Curvature friction
Friction resulting from bends or curves in the specified prestressing tendon profile
Structural Lightweight Concrete
Concrete containing lightweight aggregate
Bonded tendon
Prestressing tendon that is bonded to concrete either directly or through grouting
Structural Steel
ASTM A36
ASTM A514
High Yield Strength Quenched and Tempered Alloy Steel Plate, Suitable for Welding
TRUE
True or False, bar larger than 32mm in diameter shall not be bundled in beams
40 mm
Minimum concrete cover for a Prestressed concrete for beams and columns for primary reinforcement
Poisson’s Ratio
In a material under tension or compression, the absolute value of the ratio transverse strain to the corresponding longitudinal strain
Slenderness Ratio
In column, the ratio of its effective length to its least radius of gyration
Torsion
A quantity which measures the resistance of the mass to being revolved about a line
Flat slab
A type of concrete floor which has no beam
Shear
The tendency for one part of a beam to move vertically with respect to an adjacent part
Deformation
A change in shape of a material when subjected to the action of force
Yielding Stress
The maximum value of tension, compression, or shear respectively the material sustain without failure
Stress
-It means that by which a body develops internal resistance to stress
-Intensity of force per unit area
Allowable Stress
The greatest stress which a material is capable of developing without permanent deformation remaining upon the complete release of stress
Tie / Stirrup
Loop of reinforcing bar or wire enclosing longitudinal reinforcement
Stiffness Ration
The measure of stiffness of a material
Punching Shear
The failure in a base when a heavily loaded column strikes hole through it
Deflection
The deformation of a structural member as a result of loads acting on it
6 inches
Nominal thickness of a timber
Equilibrium
The sum of forces in the orthogonal directions and the sum of all moments about any points are zero
2 years
The complete records of tests conducted (slump, compression test, etc.) shall be preserved and made available for inspection during the progress of construction and after completion of the project for a period of not less than ___
Not less than 1”x4”
Wood board should have a thickness specification
Run
The distance from the first to the last riser of a stair flight
Portable Hand router
A high-speed rotary shaping hand power tool used to make smooth cutting and curving on solid wood
Knots
Wood defects are: heart shake, cup shake, star shake and ___
Smoothed and planed lumber
Dressed lumber is referred to ___
Live load
It refers to the occupancy load which is either partially or fully in place or may not be present at all
Cross cut saw
The other kind of handsaw other than rip cut saw
Effective Length
The distance between inflection points in the column when it breaks
Volume
The amount of space measured in cubic units
Contraction Joint
An expansion joint of adjacent parts of a structure to permit expected movements between them
Total Run
The total of all tread widths in a stair
Bond stress
The force adhesion per unit area of contact between two bonded surfaces
Purlin
A structural member spanning from truss to truss or supporting a rafter
Size of dead load deflection
Size of camber for a 25 meters steel truss
Shear connector
A connector such as a welded strut, spiral bar, or short length of channel which resists horizontal shear between elements
Shear Stress (Shearing Stress)
The force per unit area of cross section which tend to produce shear
Hook’s Law
The law that relates the linear relationship between stresses and strain
4 x diameter of bolt
Minimum spacing of bolts in timber connection measured from center of bolts parallel for parallel to grain loading is equal to ___
4 x diameter of bolt
According to the provision of the NSCP on timber connection and fastening the loaded edge distance for perpendicular to grain loading shall be at least
2.5
NSCP specifies spacing between rows of bolts for perpendicular to grain loading shall be at least ___ times bolt diameter for L/d ratio of 2
12 mm
Minimum diameter of bolts to be used in timber connections and fastening in accordance with NSCP specifications
50
Simple solid timber columns have slenderness ratio not exceeding ___
11 diameters
Nails and spikes for which the wire gauges or lengths not set forth in the NSCP specifications shall have a required penetration of not less than __
1/6 depth of member
Notches in sawn lumber bending members in accordance with the NSCP specifications shall not exceed
Middle third span
Notches in sawn lumber shall not be located in the
¼ the depth
Notches in the top and bottom of joist shall not exceed
.60 of specified yield strength
Allowable stresses for tension in structural steel in terms of gross area
.50 of specified minimum tensile strength
Allowable tensile stress of structural steel based on effective area
0.45 Fy
Allowable stress for tension on pin connected members based on net area
0.40 Fy
Allowable shear stress on structural steel on the cross sectional area effective in resisting shear
100%
For structures carrying live loads which induce impact, the assumed live load shall be increased sufficiently to provide for same, for supports of elevators the increase shall be
200
The slenderness ratio of compression members shall not exceed ___
240
The slenderness ratio main members in tension shall not exceed ___
40 mm
Concrete cover for pipes, conduits, and fittings shall not be less than ___ for concrete exposed to earth or weather
20 mm
Concrete cover for pipes, conduits, and fittings shall not be less than ___ for concrete not exposed to earth or weather
7 days
Curing of concrete (other than high-early strength) shall be maintained above 10 C and in moist condition for at least the first ___ days after placement
7 days
If concrete in structure will dry under service conditions, cores shall be air-dried for ___ days before test and shall be tested dry.
3 days
Cutting for high early strength concrete shall be maintained above 10 C and in moist condition for at least the ___days after placement
25 mm
The minimum clear spacing between parallel bars in layer shall be db (diameter of bar) but not less than ___
180 deg. Bend +4db extension but not less than 65 mm at the end of bar
Standard hooks used in reinforced concrete beam shall mean
90 deg. Bend + 6db extension at free end
Standard hooks for stirrups and tie hooks 16mm bar and smaller
90 deg. Bend + 12db extension at free end
Standard hooks for stirrups and thie hooks 20-25 mm bar
-12 mm
Allowable tolerance on minimum concrete cover for depth greater than 200 mm
+-50 mm
Allowable tolerance for longitudinal location of bends and ends of reinforcement
40 db
Individual bars with a bundle terminated within the span of flexural members shall terminate at different points with a stagger of at least
3 db
Clear distance between pre-tensioning tendons at each end of member shall not be less than ___ for strands
4 db
Clear distance between pre-tensioning tendons at each of member shall to be less than ___ for wire
75 mm
Minimum concrete cover provided for reinforcement of cast in place against permanently exposed earth or weather using bars larger than 36 mm
Structural Notes: Concrete and Steel
CONCRETE
NOMINAL MAXIMUM SIZE OF COARSE AGGREGATE SHALL NOT BE LARGER THAN:
- 1/5 the narrowest dimension between side forms
- 1/3 the depth of slabs
- ¾ the minimum clear spacing between individual reinforcing bars or wires, bundles of bars, or prestressing tendons or ducts
DEFORMED REINFORCEMENTS
- ASTM A 184 – Fabricated Deformed Steel Bar Mats
- ASTM A 185 – Steel Welded Wire Fabric, Plain
- ASTM A 496 – Steel Wire, Deformed
- ASTM A 497 – Steel Welded Wire Fabric, Deformed
- ASTM A 615M – Deformed and Plain-Billet Steel Bars
- ASTM A 616M – Rail-Steel Deformed and Plain Bars
- ASTM A 617M – Axle-Steel Deformed and Plain Bars
- ASTM A 706M – Low-Alloy Steel Deformed Bars
- ASTM A 767M – Zinc-Coated (Galvanized) Steel Bars
- ASTM A 775M – Epoxy-Coated Reinforcing Steel Bars
- ASTM A 884M – Epoxy-Coated Steel Wire and Welded Wire Fabric
- ASTM A 934M – Epoxy-Coated Prefabricated Steel Reinforcing Bars
PRESTRESSING TENDONS
- ASTM A 416M – Steel Strand, Uncoated Seven-Wire
- ASTM A 421 – Uncoated Stress-Relieved Steel Wire
- ASTM A 722 – Uncoated High-Strength Steel Bar
CURING
- concrete (other than high-early strength) shall be maintained above 10°C and in a moist condition for at least the first 7 days after placement
- high-early strength concrete shall be maintained above 10°C and in a moist condition for at least the first 3 days
CONDUITS AND PIPES EMBEDDED IN CONCRETE
- they (including their fittings) shall not displace more than 4% of the area of cross section when embedded within a column
- they shall not be larger in outside dimension than 1/3 the overall thickness of slab, wall or beam in which they are embedded
- they shall be spaced not closer than 3 diameters or widths on center
- conduits, pipes and sleeves may be considered as replacing structurally in compression the displaced concrete, provided:
o they are of uncoated or galvanized iron or steel not thinner than standard Schedule 40 steel pipe
o they have a nominal inside diameter not over 50mm and are spaced not less than 3 diameters on centers
- concrete cover shall not be less than 40mm for concrete exposed to earth or weather, or less than 20mm for concrete not exposed to weather or in contact with ground
- reinforcement with an area not less than 0.002 times the area of concrete section shall be provided normal to the piping
CONSTRUCTION JOINTS
- construction joints in floors shall be located within the middle third of spans of slabs, beams and girders
- joints in girders shall be offset a minimum distance of 2 times the width of intersecting beams
STANDARD HOOKS
- 180-degree bend plus 4db extension, but not less than 60mm at free end of bar
- 90-degree bend plus 12db extension at free end of bar
- for stirrup and tie hooks:
o 16mm diameter bar and smaller – 90-degree bend plus 6db extension at free end of bar, or
o 20 and 25mm diameter bar – 90-degree bend plus 12db extension at free end of bar, or
o 25mm diameter bar and smaller – 135-degree bend plus 6db extension at free end of bar
MINIMUM BEND DIAMETERS
- bar size of 16mm and smaller (for stirrups and ties) – 4db (inside diameter)
- bar size of 10mm through 25mm – 6db
- bar size of 28, 32 and 36mm – 8db
SPACING LIMITS FOR REINFORCEMENT
- the minimum clear spacing between parallel bars in a layer shall be db but not less than 25mm
- the minimum clear spacing between parallel bars in 2 or more layers shall not be less than 25mm between layers
- in spirally reinforced or tied reinforced compression members, clear distance between longitudinal bars shall not be less than 1.5db or less than 40mm
- in walls and slabs other than concrete joist construction, primary flexural reinforcement shall not be spaced farther apart than 3 times the wall or slab thickness, nor farther than 450mm
BUNDLED BARS
- shall be limited to 4 bars in 1 bundle
- shall be enclosed within stirrups or ties
- bars larger than 36mm diameter shall not be bundled in beams
- individual bars within a bundle terminated within the span of flexural members shall terminate at different points with at least 40db stagger
- where spacing limitations and minimum concrete cover are based on bar diameter db, a unit of bundled bars shall be treated as a single bar of a diameter derived from the equivalent total area
- minimum concrete cover shall be equal to the equivalent diameter of the bundle, but need not be greater than 50mm
PRESTRESSING TENDONS AND DUCTS
- center-to-center spacing of pretensioning tendons at each end of a member shall not be less than 5db for wire, nor 4db for strands
MINIMUM CONCRETE COVER FOR CAST-IN-PLACE CONCRETE (NONPRESTRESSED)
- concrete cast against and permanently exposed to earth – 75mm
- concrete exposed to earth or weather:
o 20mm through 36mm diameter bar – 50mm
o 16mm diameter bar and smaller – 40mm
- concrete not exposed to weather or in contact with ground:
o slabs, walls, joists:
§ 45 to 60mm diameter bars – 40mm
§ 36mm diameter bar and smaller – 20mm
o beams, columns:
§ primary reinforcement, ties, stirrups, spirals – 40mm
o shells, folded plate members:
§ 20mm diameter bar and larger – 20mm
§ 16mm diameter bar and smaller – 12mm
MINIMUM CONCRETE COVER FOR PRECAST CONCRETE
- concrete exposed to earth or weather:
o wall panels:
§ 45mm and 60mm diameter bars – 40mm
§ 36mm diameter bar and smaller – 20mm
o other members:
§ 45mm and 60mm diameter bars – 50mm
§ 20mm through 36mm diameter bar – 40mm
§ 16mm diameter bar and smaller – 30mm
- concrete not exposed to earth or in contact with ground:
o slabs, walls, joists:
§ 45mm and 60mm diameter bars – 30mm
§ 36mm diameter bar and smaller – 15mm
o beams, columns:
§ primary reinforcement – db but not less than 15mm and need not exceed 40mm
§ ties, stirrups, spirals – 10mm
o shells, folded plate members:
§ 20mm diameter bar and larger – 15mm
§ 16mm diameter bar and smaller – 10mm
MINIMUM CONCRETE COVER FOR PRESTRESSED CONCRETE
- concrete cast against and permanently exposed to earth – 75mm
- concrete exposed to earth or weather:
o wall panels, slabs, joists – 25mm
o other members – 40mm
- concrete not exposed to earth or in contact with ground:
o slabs, walls, joists – 20mm
o beams, columns:
§ primary reinforcement – 40mm
§ ties, stirrups, spirals – 25mm
o shells, folded plate members:
§ 16mm diameter bar and smaller – 10mm
§ other reinforcement – db but not less than 20mm
OFFSET BARS
- slope of inclined portion of an offset bar with axis of column shall not exceed 1 in 6
- portions of bar above and below an offset shall be parallel to axis of column
- lateral ties or spirals, if used, shall be placed not more than 150mm from points of bend
- offset bars shall be bent before placement in the forms
- where a column face is offset 75mm or greater, longitudinal bars shall not be offset bent. Separate dowels, lap sliced with the longitudinal bars adjacent to the offset column faces, shall be provided
SPIRALS
- for cast-in-place construction, size of spirals shall not be less than 10mm diameter
- clear spacing between spirals shall not exceed 75mm or be less than 25mm
- anchorage of spiral reinforcement shall be provided by 1½ extra turns of spiral bar or wire at each end of a spiral unit
- spiral reinforcement shall be lap spliced by 48db but not less than 300mm or welded
- in columns with capitals, spirals shall extend to a level at which the diameter or width of capital is 2 times that of the column
- plain bars shall conform to one of the following specifications:
o ASTM A 615M
o ASTM A 616M
o ASTM A 617M
- plain wire shall conform to:
o ASTM A 82 – Steel Wire, Plain
TIES
- 10mm diameter lateral ties for longitudinal bars 32mm diameter or smaller
- 12mm diameter lateral ties for longitudinal bars 36 diameter and bundled bars
- vertical spacing of ties shall not exceed:
o 16db of longitudinal bars
o 48db of tie bars
o least dimension of compression member
- ties shall be arranged that no bar shall be farther than 150mm clear on each side along the tie
- ties shall be located vertically not more than ½ a tie spacing above the top of footing or slab in any story
- where beams or brackets frame from 4 directions into a column, termination of ties not more than 75mm below reinforcement in shallowest of such beams or brackets shall be permitted
SHRINKAGE AND TEMPERATURE REINFORCEMENT
- shrinkage and temperature reinforcement shall be spaced not farther apart than 5 times the slab thickness, or 450mm
- spacing of prestressed tendons shall not exceed 1.80m
T-BEAM CONSTRUCTION
- the flange and web shall be built integrally or otherwise effectively bonded together
- width of slab effective as a T-beam flange on each side of the web shall not exceed:
o ¼ the span length of the beam,
o 8 times the slab thickness, or
o ½ the clear distance to the next web
- for beams with a slab on one side only, the effective overhanging flange width shall not exceed:
o 1/12 the span length of the beam,
o 6 times the slab thickness, or
o ½ the clear distance to the next web
- transverse reinforcement shall be spaced not farther apart than 5 times the slab thickness, nor 450mm
JOIST CONSTRUCTION
- ribs shall not be less than 100mm in width and shall have a depth of not more than 3½ times the minimum width of rib
- clear spacing between ribs shall not exceed 750mm
- slab thickness over permanent fillers shall not be less than 1/12 the clear distance between ribs nor less than 40mm
- when removable forms or fillers are used, slab thickness shall not be les than 1/12 the clear distance between ribs, or less than 50mm
- where conduits or pipes are embedded within the slab, slab thickness shall be at least 25mm greater than the total overall depth of the conduits or pipes at any point
REQUIRED STRENGTH
- dead load and live load
o U = 1.4D + 1.7L
- dead load, live load and wind load
o U = 0.75 (1.4D + 1.7L + 1.7W)
o U = 0.9D + 1.3W
- dead load, live load and earthquake load
o U = 1.3D + 1.1L + 1.1E
o U = 0.99D + 1.1E
STRENGTH-REDUCTION FACTOR
- flexure without axial load, 0.90
- axial tension and axial tension with flexure, 0.90
- axial compression and axial compression with flexure:
o spiral reinforced, 0.75
o tie reinforce, 0.70
- shear and torsion, 0.85
- bearing on concrete, 0.70
- post-tensioned anchorage zones, 0.85
MINIMUM THICKNESS OF NONPRESTRESSED BEAMS OR ONE-WAY SLABS UNLESS DEFLECTIONS ARE COMPUTED (members are not supporting or attached to partitions or other construction likely to be damaged by large deflections)
- solid one-way slabs:
o simply supported, L/20
o one end continuous, L/24
o both ends continuous, L/28
o cantilever, L/10
- beams or ribbed one-way slabs:
o simply supported, L/16
o one end continuous, L/18.5
o both ends continuous, L/21
o cantilever, L/8
- for Fy other than 415Mpa, the values shall be multiplied by (0.4 + Fy/700)
DISTANCE BETWEEN LATERAL SUPPORTS OF FLEXURAL MEMBERS
- spacing of lateral supports for a beam shall not exceed 50 times the least width b of compression flange or face
LIMITS FOR REINFORCEMENT OF COMPRESSION MEMBERS
- minimum number of longitudinal bars in compression members shall be 3 for bars within triangular ties, 4 for bars within rectangular or circular ties, and 6 for bars enclosed by spirals
SPACING LIMITS FOR SHEAR REINFORCEMENT
- shall not exceed d/2 in non-prestressed members and 3/4h in prestressed members or 600mm
SPLICES
- lap splices shall not be used for bars larger than 36mm diameter
- lap splices of bars in a bundle shall be based on the lap splice length required for individual bars within the bundle
- individual bar splices within a bundle shall not overlap
- entire bundles shall not be lap spliced
- bars spliced by non-contact lap splices in flexural members shall not be spaced transversely farther apart than 1/5 the required lap splice length, or 150mm
- splices shall be staggered at least 600mm
WALLS
- minimum ratio of vertical reinforcement area to gross concrete area shall be:
o 0.0012 – deformed bars not larger than 16mm diameter with a specified yield strength not less than 420Mpa, or
o 0.0015 – for other deformed bars, or
o 0.0012 – for welded wire fabric (plain or deformed)
- minimum ratio of horizontal reinforcement area to gross concrete area shall be:
o 0.0020 – deformed bars not larger than 16mm diameter with a specified yield strength not less than 420 Mpa, or
o 0.0025 – for other deformed bars, or
o 0.0020 – for welded wire fabric (palin or deformed)
- in addition to the minimum reinforcement required, not less than 2-16mm diameter bars shall be provided around all window and door openings. Such bars shall be extended to develop the bar beyond the corners of the openings but not less than 600mm
NON-BEARING WALLS
- thickness shall not be less than 100mm, or not less than 1/30 the least distance between members that provide lateral support
MINIMUM FOOTING DEPTH
- depth of footing above bottom reinforcement shall not be less than 150mm for footings on soil, or not less than 300mm for footings on piles
TRANSVERSE REINFORCEMENT (HOOPS)
- the first hoop shall be located not more than 50mm from the face of a supporting member
- maximum spacing of the hoops shall not exceed:
o d/4
o 8 times the diameter of the smallest longitudinal bar
o 24 times the diameter of the hoop bars
o 300mm
- where hoops are not required, stirrups shall be placed at no more than d/2 throughout the length of the member
STRUCTURAL STEEL
LIMITING SLENDERNESS RATIOS
- for members whose design is based on compressive force, the slenderness ratio preferably should not exceed 200
- for members whose designed is based on tensile force, the slenderness ratio preferably should not exceed 300
ALLOWABLE STRESSES
- for tension in structural steel in terms of gross area, 0.60Fy
- for tension in structural steel based on effective net area, 0.50Fu
- for tension on pin-connected members based on net area, 0.45Fy
- for tension on eyebars on the body area, 0.60Fy
- for flexural members with compact sections, Fb = 0.66Fy
- for flexural members with non-compact sections, Fb = 0.60Fy
PIN-CONNECTED MEMBERS
- minimum net area beyond the pinhole, parallel to the axis of the member, shall not be less than 2/3 of the net area across the pinhole
- width of the body of an eyebar shall not exceed 8 times its thickness
- pin diameter shall not be less than 7/8 times the eyebar width
- pinhole diameter shall be no more than 0.8mm greater than the pin diameter
SHEAR CONNECTORS
- shear connectors shall have at least 25mm of lateral concrete cover
- diameter of studs shall not be greater than 2½ times the thickness of the flange to which they are welded
- minimum center-to-center spacing of stud connectors shall be 6 diameters along the longitudinal axis and 4 diameters transverse to the longitudinal axis maximum center-to-center spacing of stud connectors shall not exceed 8 times the total slab thickness
WELDS
- weld access holes shall have a length from the toe of the weld preparation not less than 1½ times the thickness of the material in which the hole is made
- groove welds:
o effective area = effective length of the weld x effective throat thickness
o effective length = width of the part joined
o effective throat thickness of a complete-penetration groove weld = thickness of the thinner part joined
o minimum effective throat thickness of partial-penetration groove welds =
§ 3mm (thicker part joined to 6mm inclusive)
§ 5mm (thicker part joined over 6 to 12mm)
§ 6mm (thicker part joined over 12 to 20mm)
§ 8mm (thicker part joined over 20 to 38mm)
§ 10mm (thicker part joined over 38 to 57mm)
§ 12mm (thicker part joined over 57 to 150mm)
§ 16mm (thicker part joined over 150mm)
o effective throat thickness of a flare groove weld =
§ flare bevel groove, 5/16R
§ flare V-groove, ½R
- fillet welds:
o effective area of fillet welds = effective length x effective throat thickness
o effective throat thickness of a fillet weld = shortest distance from the root of the joint to the face of the diagrammatic weld
o minimum size of fillet welds =
§ 3mm (thicker part joined to 6mm inclusive)
§ 5mm (thicker part joined over 6 to 12mm)
§ 6mm (thicker part joined over 12 to 20mm)
§ 8mm (thicker part joined over 20mm)
o maximum size of fillet welds along edges =
§ not greater than the thickness of the material (material less than 6mm thick)
§ not greater than the thickness of the material minus 1.6mm (material 6mm or more in thickness)
o minimum effective length of a fillet weld designed on the basis of strength shall not be less than 4 times its nominal size
o if greater than 4 times its nominal size, the size of the weld should not exceed ¼ its effective length
o effective length of any segment of intermittent fillet welding shall not be less than 4 times the weld size, with a minimum of 38mm
o in lap joints, minimum lap shall be 5 times the thickness of the thinner part joined, but not less than 25mm
o slide or end fillet welds terminating at ends or sides, respectively, of parts or members shall, wherever practicable, be returned continuously around the corners for a distance not less than 2 times the nominal size of the weld
- plug and slot welds:
o diameter of the hole for a plug weld shall not be less than the thickness of the part containing it plus 8mm, nor greater than the minimum diameter plus 3mm or 2¼ times the thickness of the weld
o minimum spacing of lines of slot welds in a direction transverse to their length shall be 4 times the width of the slot
o minimum center-to-center spacing in a longitudinal direction shall be 2 times the length of the slot
o length of the slot shall not exceed 10 times the thickness of the weld
o width of the slot shall not be less than the thickness of the part containing it plus 8mm, nor shall it be larger than 2¼ times the thickness of the weld
o thickness of plug or slot welds in material 16mm or less thick = thickness of the material
o thickness of plug or slot welds in material over 16mm thick = ½ the thickness of the material but not less than 16mm
FASTENERS
- distance between centers of standard, oversized or slotted fastener holes shall not be less than 2 2/3 times the nominal diameter of the fastener
- maximum distance from the center of any rivet or bolt to the nearest edge of parts in contact shall be 12 times the thickness of the connected part, but shall not exceed 150mm
CAMBER
- trusses of 24.4m or greater span generally shall be cambered for approximately the dead-load deflection
- crane girders of 22.9m or greater span generally shall be cambered for approximately the dead-load deflection plus ½ the live-load deflection
NOMINAL MAXIMUM SIZE OF COARSE AGGREGATE SHALL NOT BE LARGER THAN:
- 1/5 the narrowest dimension between side forms
- 1/3 the depth of slabs
- ¾ the minimum clear spacing between individual reinforcing bars or wires, bundles of bars, or prestressing tendons or ducts
DEFORMED REINFORCEMENTS
- ASTM A 184 – Fabricated Deformed Steel Bar Mats
- ASTM A 185 – Steel Welded Wire Fabric, Plain
- ASTM A 496 – Steel Wire, Deformed
- ASTM A 497 – Steel Welded Wire Fabric, Deformed
- ASTM A 615M – Deformed and Plain-Billet Steel Bars
- ASTM A 616M – Rail-Steel Deformed and Plain Bars
- ASTM A 617M – Axle-Steel Deformed and Plain Bars
- ASTM A 706M – Low-Alloy Steel Deformed Bars
- ASTM A 767M – Zinc-Coated (Galvanized) Steel Bars
- ASTM A 775M – Epoxy-Coated Reinforcing Steel Bars
- ASTM A 884M – Epoxy-Coated Steel Wire and Welded Wire Fabric
- ASTM A 934M – Epoxy-Coated Prefabricated Steel Reinforcing Bars
PRESTRESSING TENDONS
- ASTM A 416M – Steel Strand, Uncoated Seven-Wire
- ASTM A 421 – Uncoated Stress-Relieved Steel Wire
- ASTM A 722 – Uncoated High-Strength Steel Bar
CURING
- concrete (other than high-early strength) shall be maintained above 10°C and in a moist condition for at least the first 7 days after placement
- high-early strength concrete shall be maintained above 10°C and in a moist condition for at least the first 3 days
CONDUITS AND PIPES EMBEDDED IN CONCRETE
- they (including their fittings) shall not displace more than 4% of the area of cross section when embedded within a column
- they shall not be larger in outside dimension than 1/3 the overall thickness of slab, wall or beam in which they are embedded
- they shall be spaced not closer than 3 diameters or widths on center
- conduits, pipes and sleeves may be considered as replacing structurally in compression the displaced concrete, provided:
o they are of uncoated or galvanized iron or steel not thinner than standard Schedule 40 steel pipe
o they have a nominal inside diameter not over 50mm and are spaced not less than 3 diameters on centers
- concrete cover shall not be less than 40mm for concrete exposed to earth or weather, or less than 20mm for concrete not exposed to weather or in contact with ground
- reinforcement with an area not less than 0.002 times the area of concrete section shall be provided normal to the piping
CONSTRUCTION JOINTS
- construction joints in floors shall be located within the middle third of spans of slabs, beams and girders
- joints in girders shall be offset a minimum distance of 2 times the width of intersecting beams
STANDARD HOOKS
- 180-degree bend plus 4db extension, but not less than 60mm at free end of bar
- 90-degree bend plus 12db extension at free end of bar
- for stirrup and tie hooks:
o 16mm diameter bar and smaller – 90-degree bend plus 6db extension at free end of bar, or
o 20 and 25mm diameter bar – 90-degree bend plus 12db extension at free end of bar, or
o 25mm diameter bar and smaller – 135-degree bend plus 6db extension at free end of bar
MINIMUM BEND DIAMETERS
- bar size of 16mm and smaller (for stirrups and ties) – 4db (inside diameter)
- bar size of 10mm through 25mm – 6db
- bar size of 28, 32 and 36mm – 8db
SPACING LIMITS FOR REINFORCEMENT
- the minimum clear spacing between parallel bars in a layer shall be db but not less than 25mm
- the minimum clear spacing between parallel bars in 2 or more layers shall not be less than 25mm between layers
- in spirally reinforced or tied reinforced compression members, clear distance between longitudinal bars shall not be less than 1.5db or less than 40mm
- in walls and slabs other than concrete joist construction, primary flexural reinforcement shall not be spaced farther apart than 3 times the wall or slab thickness, nor farther than 450mm
BUNDLED BARS
- shall be limited to 4 bars in 1 bundle
- shall be enclosed within stirrups or ties
- bars larger than 36mm diameter shall not be bundled in beams
- individual bars within a bundle terminated within the span of flexural members shall terminate at different points with at least 40db stagger
- where spacing limitations and minimum concrete cover are based on bar diameter db, a unit of bundled bars shall be treated as a single bar of a diameter derived from the equivalent total area
- minimum concrete cover shall be equal to the equivalent diameter of the bundle, but need not be greater than 50mm
PRESTRESSING TENDONS AND DUCTS
- center-to-center spacing of pretensioning tendons at each end of a member shall not be less than 5db for wire, nor 4db for strands
MINIMUM CONCRETE COVER FOR CAST-IN-PLACE CONCRETE (NONPRESTRESSED)
- concrete cast against and permanently exposed to earth – 75mm
- concrete exposed to earth or weather:
o 20mm through 36mm diameter bar – 50mm
o 16mm diameter bar and smaller – 40mm
- concrete not exposed to weather or in contact with ground:
o slabs, walls, joists:
§ 45 to 60mm diameter bars – 40mm
§ 36mm diameter bar and smaller – 20mm
o beams, columns:
§ primary reinforcement, ties, stirrups, spirals – 40mm
o shells, folded plate members:
§ 20mm diameter bar and larger – 20mm
§ 16mm diameter bar and smaller – 12mm
MINIMUM CONCRETE COVER FOR PRECAST CONCRETE
- concrete exposed to earth or weather:
o wall panels:
§ 45mm and 60mm diameter bars – 40mm
§ 36mm diameter bar and smaller – 20mm
o other members:
§ 45mm and 60mm diameter bars – 50mm
§ 20mm through 36mm diameter bar – 40mm
§ 16mm diameter bar and smaller – 30mm
- concrete not exposed to earth or in contact with ground:
o slabs, walls, joists:
§ 45mm and 60mm diameter bars – 30mm
§ 36mm diameter bar and smaller – 15mm
o beams, columns:
§ primary reinforcement – db but not less than 15mm and need not exceed 40mm
§ ties, stirrups, spirals – 10mm
o shells, folded plate members:
§ 20mm diameter bar and larger – 15mm
§ 16mm diameter bar and smaller – 10mm
MINIMUM CONCRETE COVER FOR PRESTRESSED CONCRETE
- concrete cast against and permanently exposed to earth – 75mm
- concrete exposed to earth or weather:
o wall panels, slabs, joists – 25mm
o other members – 40mm
- concrete not exposed to earth or in contact with ground:
o slabs, walls, joists – 20mm
o beams, columns:
§ primary reinforcement – 40mm
§ ties, stirrups, spirals – 25mm
o shells, folded plate members:
§ 16mm diameter bar and smaller – 10mm
§ other reinforcement – db but not less than 20mm
OFFSET BARS
- slope of inclined portion of an offset bar with axis of column shall not exceed 1 in 6
- portions of bar above and below an offset shall be parallel to axis of column
- lateral ties or spirals, if used, shall be placed not more than 150mm from points of bend
- offset bars shall be bent before placement in the forms
- where a column face is offset 75mm or greater, longitudinal bars shall not be offset bent. Separate dowels, lap sliced with the longitudinal bars adjacent to the offset column faces, shall be provided
SPIRALS
- for cast-in-place construction, size of spirals shall not be less than 10mm diameter
- clear spacing between spirals shall not exceed 75mm or be less than 25mm
- anchorage of spiral reinforcement shall be provided by 1½ extra turns of spiral bar or wire at each end of a spiral unit
- spiral reinforcement shall be lap spliced by 48db but not less than 300mm or welded
- in columns with capitals, spirals shall extend to a level at which the diameter or width of capital is 2 times that of the column
- plain bars shall conform to one of the following specifications:
o ASTM A 615M
o ASTM A 616M
o ASTM A 617M
- plain wire shall conform to:
o ASTM A 82 – Steel Wire, Plain
TIES
- 10mm diameter lateral ties for longitudinal bars 32mm diameter or smaller
- 12mm diameter lateral ties for longitudinal bars 36 diameter and bundled bars
- vertical spacing of ties shall not exceed:
o 16db of longitudinal bars
o 48db of tie bars
o least dimension of compression member
- ties shall be arranged that no bar shall be farther than 150mm clear on each side along the tie
- ties shall be located vertically not more than ½ a tie spacing above the top of footing or slab in any story
- where beams or brackets frame from 4 directions into a column, termination of ties not more than 75mm below reinforcement in shallowest of such beams or brackets shall be permitted
SHRINKAGE AND TEMPERATURE REINFORCEMENT
- shrinkage and temperature reinforcement shall be spaced not farther apart than 5 times the slab thickness, or 450mm
- spacing of prestressed tendons shall not exceed 1.80m
T-BEAM CONSTRUCTION
- the flange and web shall be built integrally or otherwise effectively bonded together
- width of slab effective as a T-beam flange on each side of the web shall not exceed:
o ¼ the span length of the beam,
o 8 times the slab thickness, or
o ½ the clear distance to the next web
- for beams with a slab on one side only, the effective overhanging flange width shall not exceed:
o 1/12 the span length of the beam,
o 6 times the slab thickness, or
o ½ the clear distance to the next web
- transverse reinforcement shall be spaced not farther apart than 5 times the slab thickness, nor 450mm
JOIST CONSTRUCTION
- ribs shall not be less than 100mm in width and shall have a depth of not more than 3½ times the minimum width of rib
- clear spacing between ribs shall not exceed 750mm
- slab thickness over permanent fillers shall not be less than 1/12 the clear distance between ribs nor less than 40mm
- when removable forms or fillers are used, slab thickness shall not be les than 1/12 the clear distance between ribs, or less than 50mm
- where conduits or pipes are embedded within the slab, slab thickness shall be at least 25mm greater than the total overall depth of the conduits or pipes at any point
REQUIRED STRENGTH
- dead load and live load
o U = 1.4D + 1.7L
- dead load, live load and wind load
o U = 0.75 (1.4D + 1.7L + 1.7W)
o U = 0.9D + 1.3W
- dead load, live load and earthquake load
o U = 1.3D + 1.1L + 1.1E
o U = 0.99D + 1.1E
STRENGTH-REDUCTION FACTOR
- flexure without axial load, 0.90
- axial tension and axial tension with flexure, 0.90
- axial compression and axial compression with flexure:
o spiral reinforced, 0.75
o tie reinforce, 0.70
- shear and torsion, 0.85
- bearing on concrete, 0.70
- post-tensioned anchorage zones, 0.85
MINIMUM THICKNESS OF NONPRESTRESSED BEAMS OR ONE-WAY SLABS UNLESS DEFLECTIONS ARE COMPUTED (members are not supporting or attached to partitions or other construction likely to be damaged by large deflections)
- solid one-way slabs:
o simply supported, L/20
o one end continuous, L/24
o both ends continuous, L/28
o cantilever, L/10
- beams or ribbed one-way slabs:
o simply supported, L/16
o one end continuous, L/18.5
o both ends continuous, L/21
o cantilever, L/8
- for Fy other than 415Mpa, the values shall be multiplied by (0.4 + Fy/700)
DISTANCE BETWEEN LATERAL SUPPORTS OF FLEXURAL MEMBERS
- spacing of lateral supports for a beam shall not exceed 50 times the least width b of compression flange or face
LIMITS FOR REINFORCEMENT OF COMPRESSION MEMBERS
- minimum number of longitudinal bars in compression members shall be 3 for bars within triangular ties, 4 for bars within rectangular or circular ties, and 6 for bars enclosed by spirals
SPACING LIMITS FOR SHEAR REINFORCEMENT
- shall not exceed d/2 in non-prestressed members and 3/4h in prestressed members or 600mm
SPLICES
- lap splices shall not be used for bars larger than 36mm diameter
- lap splices of bars in a bundle shall be based on the lap splice length required for individual bars within the bundle
- individual bar splices within a bundle shall not overlap
- entire bundles shall not be lap spliced
- bars spliced by non-contact lap splices in flexural members shall not be spaced transversely farther apart than 1/5 the required lap splice length, or 150mm
- splices shall be staggered at least 600mm
WALLS
- minimum ratio of vertical reinforcement area to gross concrete area shall be:
o 0.0012 – deformed bars not larger than 16mm diameter with a specified yield strength not less than 420Mpa, or
o 0.0015 – for other deformed bars, or
o 0.0012 – for welded wire fabric (plain or deformed)
- minimum ratio of horizontal reinforcement area to gross concrete area shall be:
o 0.0020 – deformed bars not larger than 16mm diameter with a specified yield strength not less than 420 Mpa, or
o 0.0025 – for other deformed bars, or
o 0.0020 – for welded wire fabric (palin or deformed)
- in addition to the minimum reinforcement required, not less than 2-16mm diameter bars shall be provided around all window and door openings. Such bars shall be extended to develop the bar beyond the corners of the openings but not less than 600mm
NON-BEARING WALLS
- thickness shall not be less than 100mm, or not less than 1/30 the least distance between members that provide lateral support
MINIMUM FOOTING DEPTH
- depth of footing above bottom reinforcement shall not be less than 150mm for footings on soil, or not less than 300mm for footings on piles
TRANSVERSE REINFORCEMENT (HOOPS)
- the first hoop shall be located not more than 50mm from the face of a supporting member
- maximum spacing of the hoops shall not exceed:
o d/4
o 8 times the diameter of the smallest longitudinal bar
o 24 times the diameter of the hoop bars
o 300mm
- where hoops are not required, stirrups shall be placed at no more than d/2 throughout the length of the member
STRUCTURAL STEEL
LIMITING SLENDERNESS RATIOS
- for members whose design is based on compressive force, the slenderness ratio preferably should not exceed 200
- for members whose designed is based on tensile force, the slenderness ratio preferably should not exceed 300
ALLOWABLE STRESSES
- for tension in structural steel in terms of gross area, 0.60Fy
- for tension in structural steel based on effective net area, 0.50Fu
- for tension on pin-connected members based on net area, 0.45Fy
- for tension on eyebars on the body area, 0.60Fy
- for flexural members with compact sections, Fb = 0.66Fy
- for flexural members with non-compact sections, Fb = 0.60Fy
PIN-CONNECTED MEMBERS
- minimum net area beyond the pinhole, parallel to the axis of the member, shall not be less than 2/3 of the net area across the pinhole
- width of the body of an eyebar shall not exceed 8 times its thickness
- pin diameter shall not be less than 7/8 times the eyebar width
- pinhole diameter shall be no more than 0.8mm greater than the pin diameter
SHEAR CONNECTORS
- shear connectors shall have at least 25mm of lateral concrete cover
- diameter of studs shall not be greater than 2½ times the thickness of the flange to which they are welded
- minimum center-to-center spacing of stud connectors shall be 6 diameters along the longitudinal axis and 4 diameters transverse to the longitudinal axis maximum center-to-center spacing of stud connectors shall not exceed 8 times the total slab thickness
WELDS
- weld access holes shall have a length from the toe of the weld preparation not less than 1½ times the thickness of the material in which the hole is made
- groove welds:
o effective area = effective length of the weld x effective throat thickness
o effective length = width of the part joined
o effective throat thickness of a complete-penetration groove weld = thickness of the thinner part joined
o minimum effective throat thickness of partial-penetration groove welds =
§ 3mm (thicker part joined to 6mm inclusive)
§ 5mm (thicker part joined over 6 to 12mm)
§ 6mm (thicker part joined over 12 to 20mm)
§ 8mm (thicker part joined over 20 to 38mm)
§ 10mm (thicker part joined over 38 to 57mm)
§ 12mm (thicker part joined over 57 to 150mm)
§ 16mm (thicker part joined over 150mm)
o effective throat thickness of a flare groove weld =
§ flare bevel groove, 5/16R
§ flare V-groove, ½R
- fillet welds:
o effective area of fillet welds = effective length x effective throat thickness
o effective throat thickness of a fillet weld = shortest distance from the root of the joint to the face of the diagrammatic weld
o minimum size of fillet welds =
§ 3mm (thicker part joined to 6mm inclusive)
§ 5mm (thicker part joined over 6 to 12mm)
§ 6mm (thicker part joined over 12 to 20mm)
§ 8mm (thicker part joined over 20mm)
o maximum size of fillet welds along edges =
§ not greater than the thickness of the material (material less than 6mm thick)
§ not greater than the thickness of the material minus 1.6mm (material 6mm or more in thickness)
o minimum effective length of a fillet weld designed on the basis of strength shall not be less than 4 times its nominal size
o if greater than 4 times its nominal size, the size of the weld should not exceed ¼ its effective length
o effective length of any segment of intermittent fillet welding shall not be less than 4 times the weld size, with a minimum of 38mm
o in lap joints, minimum lap shall be 5 times the thickness of the thinner part joined, but not less than 25mm
o slide or end fillet welds terminating at ends or sides, respectively, of parts or members shall, wherever practicable, be returned continuously around the corners for a distance not less than 2 times the nominal size of the weld
- plug and slot welds:
o diameter of the hole for a plug weld shall not be less than the thickness of the part containing it plus 8mm, nor greater than the minimum diameter plus 3mm or 2¼ times the thickness of the weld
o minimum spacing of lines of slot welds in a direction transverse to their length shall be 4 times the width of the slot
o minimum center-to-center spacing in a longitudinal direction shall be 2 times the length of the slot
o length of the slot shall not exceed 10 times the thickness of the weld
o width of the slot shall not be less than the thickness of the part containing it plus 8mm, nor shall it be larger than 2¼ times the thickness of the weld
o thickness of plug or slot welds in material 16mm or less thick = thickness of the material
o thickness of plug or slot welds in material over 16mm thick = ½ the thickness of the material but not less than 16mm
FASTENERS
- distance between centers of standard, oversized or slotted fastener holes shall not be less than 2 2/3 times the nominal diameter of the fastener
- maximum distance from the center of any rivet or bolt to the nearest edge of parts in contact shall be 12 times the thickness of the connected part, but shall not exceed 150mm
CAMBER
- trusses of 24.4m or greater span generally shall be cambered for approximately the dead-load deflection
- crane girders of 22.9m or greater span generally shall be cambered for approximately the dead-load deflection plus ½ the live-load deflection
Monday, March 19, 2012
SOUND ACOUSTICS TERMINOLOGY
SOUND ACOUSTICS TERMINOLOGY
Acoustics
The science that studies the waves that are conducted through matter due to the motion of the matter. Usually air is the material that most people think of when it comes to acoustic waves. But acoustic waves exist in all matter. Architectural acoustics, is the study of acoustics when the air is contained in a room. Church acoustics is a sub-division of architectural acoustics..
Sound (waves)
Pressure fluctuations in the air that are heard when an acoustic wave passes by. They are usually caused by objects in the air that quickly change position or a stream of air that quickly changes position. Sound escapes away from the sound source as an expanding spherical wave that travels at the speed of 1130 feet per second, traveling about 1 1/8th of a foot each one thousandths of a second (millisecond)..
Sound Level
The measure of the strength of sound. Units are decibels (dB) and usually measured with a dB meter. The threshold of quiet sound is zero dB and the onset of painful sound is 100 dB. Conversations are at 50 dB, whispers at 30 dB and shouting is 70 dB. When the sound strength of something doubles, it increases by 3 dB, or halved, it drops by 3 dB.
Loudness
The apparent strength of the sound to the listener. A change in 1 dB is just barely noticed as a change in loudness. Something twice as loud is actually 10 dB stronger, (10 times stronger). Something half as loud is 10 dB weaker, (1/10th as strong).
Direct Sound (direct signal)
The part of a sound wave that travels directly along the line of sight path between the speaker or sound source and the listener. The dry or actual sound.
Reflections
Sound waves that strike a surface and bounce off are reflected sounds. They bounce off the wall, changing directions but keeping the same angle off the wall as they had when they approached the wall.
Early Reflections
Reflections that are heard within 1/20 of a second of the direct sound are called early reflections. Early reflections cannot be distinguished from direct signals, they merge with the direct sound to form one composite sound. This combining effect can cause the sound of the direct signal to change in tonal characteristics and apparent direction.
Late reflections (Echoes)
A distinct reflection that arrives at the listener later than 1/20th of a second after the direct sound is heard. The listener can identify from where an echo comes. An echo does not change the tonal characteristics of the direct sound.
Flutter Echo
This type of echo is most easily heard as one claps their hands out in front of them, while standing in a hallway. The sound "zings" and it's tone depends on how many times a second the reflection passes by the listener's head. In a hall 8' wide, the clap will expand out, hit the wall and return 143 times a second and the zing will sound like a 143 Hz buzzy tone. Not a real sound, just a pseudo-tone.
Reverberation
For sound in a large room, reverberation begins at about 1/5 second following the direct sound. It is due to the accumulation of many reflections, compounding one upon the other, so much that the sound no longer seems composed of echoes but rather just a sound of noise, a din of chaos that has no discrete direction and no discrete timing.
Diffusion
Reflections off of a non flat surface that causes the sound wave to become more quickly disorganized than if off a flat surface is a diffusive surface. Diffusion decreases the time it takes for echoes to become converted to reverberation. The beautiful gothic churches of the old world have very diffusive or sound scattering surfaces. That is part of the sonic beauty of those spaces.
Decay
The dying out of sound. Usually referring to the steady decline in the loudness of the reverberation.
Decay Rate (RT-60)
The time (in seconds) it takes for reverberation to change from very loud to imperceptibly quiet, a total sound level difference of 60 dB. For a living room the RT-60 might be 1 second but in a gym, it might be 4 seconds.
Absorption
The loss of sound energy that occurs when the sound wave strikes a fibrous surface. The fibers provide acoustic friction for the sound wave. The wave does not slow down due to the friction, it keeps it's same speed but it does lose energy and get quieter.
NRC Rating
(Noise Reduction Coefficient) A rating for absorption. It gives the % efficiency for a surface to absorb sound. If a surface is 30% absorptive, then only 70% of the incident sound is reflected back into the room.
Noise (Background Noise)
The unwanted, undesirable and usually interfering sounds present in a listening space, typically due to an air conditioner or other conversations.
Noise Floor
The strength of the background noise, measured in dB. It is difficult to understand what is being said in a room with a high noise floor.
Signal-to-Noise Ratio (S/N ratio)
The difference in sound level (dB) between the desired sound and the noise floor.
Articulation
The clarity of a sound, particularly a message conveyed by sound, such that it can be easily and completely understood. A slurred sound may be well heard but the message it carries may still not be well understood, it is inarticulate. Also, a clear and distinct sound may be drowned out by a nearby louder noise, rendering the message not understandable, inarticulate. Echoes also cause articulation problems. Articulation is most often measured in some form of a desired signal to unwanted noise ratio.
Intelligibility
A measure of the clarity of sound based on the comprehension of the message being conveyed by sound. A "cat, bat, tat, rat... type of recognition test. The conversational version of Articulation.
Bright/Lively
The condition of sound in which there is an abundance of treble range reflections giving the feeling of "brightness" or "liveliness" to the sound. Sound in a tile bathroom or kitchen is bright. Too much can seem harsh and irritating.
Dark/Dead
The condition of sound in a room when there is a lack of reflections and a lack of reverberance. Too much can seem lack-luster and uneasy feeling.
Boomy
The condition of sound in a room when the lower frequencies, particularly the male voice range is excessively reverberant.
Psychoacoustics
The study and science of how the human comprehends and makes sense out of the sounds they hear. The difference between an early reflection and a late (echo) reflection, is an example of psychoacoustics. The blending of the early reflections with the direct sound is another.
Audiology
The science and practice of amplifying or otherwise improving how well a person hears sound.
Frequency (Hertz, Hz, cps)
A single sound pulse as from a fire cracker has sound energy but no tone. Tones are sounds that come from voices or instruments which have a repetitive pressure pulse characteristic. The number of repeat times per second that a sound has is called it's frequency. It's unit of measurement is cycles per second (cps) also called Hz (Hertz). Similar to pitch in musical terms.
Sound Spectrum
The sound level measured at different frequencies. Most tones are composed of more than one frequency, a combination of frequencies, as in a musical chord. The sound spectrum would measure the strength of each frequency and display that graph as a plot of Sound Level vs. Frequency, also known as a sound spectrum. The "color" of sound is used as emphasis in the spectrum.
Sonic Color
The shift in emphasis of a complex sound within it's spectral range. A neutral color is the preferred natural sound but sometimes sound can have a warm color, an emphasis on lower frequencies or a cold color, an emphasis on higher frequencies or a nasal color, an emphasis on midrange frequencies.
Ultrasonics
Sound whose frequency range is above that of human hearing, above 20,000 Hz.
Infrasonics
Sound whose frequency range is below that of human hearing, below 20 Hz.
Octave
Sound that exists within a limited frequency range, between a lower set frequency and a set upper frequency. The difference between the lower and upper frequency is specified to be equal to the lower frequency. The octave sequence for the note "C" starts at 31 Hz and continues thru 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1k Hz, 2k Hz, 4k Hz, 8k Hz and ends at 16k Hz. (k = thousand).
Voicing
The process of defining the desirable condition of sound in an acoustic space. It integrates the direct, early and late reflections with the reverberation, including a sense of timing and direction for each into an appropriate and desirable acoustic condition for the listener. It combines both the art and science of sound. It requires an understanding of the purpose to be served by each acoustic space. As an art form, it recognizes the aesthetic side of sound, the impression that most people prefer to have of each particular type of sound that exists in some particular place. As a science, it is based on psychoacoustics.
Acoustician
An acoustical engineer who is trained and experienced in voicing rooms.
Acoustical Engineer
One formally educated, experienced in the science and practice of acoustics.
Sound Engineer
Someone trained in setting up microphones and speakers.
Acoustic Contractor
Someone trained and experienced in installing acoustic tiles and wall panels.
Acoustic Consultant
Someone, not formally trained, experienced in providing acoustical services.
Acoustic Designer
Someone, not formally trained, who prepares blueprints for acoustic projects.
Sound Designer
One who envisions and directs the way sound plays out of a stage..
Auditorium Acoustics 101:
The Quieter, the Better
Let's start with the basics. The architect designs a great looking and comfortable auditorium. The sound contractor installs a great looking sound system. The people attend the grand opening and are impressed with what they see, but they have gathered for more than a dazzling display of architecture, lighting, electronics, carpets, glass, surface textures and paint. They have come to be in an auditorium, a place to hear and, moreover, a place to listen to and learn from the lecture or, as the case may be, the sermon. The outer beauty of an auditorium is recognized by how it looks, but the inner more lasting beauty of the auditorium is truly known by how it sounds. And with this we mark the beginning of our journey into auditorium acoustics.
Lots of sound, but little is heard
A sound wave starts at the loud speaker, which is suspended high overhead in the front of the hall. Seated way below, are the many people who came to hear that sound. The greater the size of the audience, the farther from the speaker they have to sit. An audience of 1,000 people would occupy about 8,000 square feet of floor space. A member of that audience typically might be seated some 50 feet away from the loudspeaker. The sound wave emitted by the loudspeaker spreads out in the shape of an expanding quarter sphere. By the time this wave reaches the audience, it has expanded out to a radius of about 50 feet. It has spread out over a quarter sphere surface area of 7,850 square feet or about 1.13 million square inches.
Each ear of a person collects about one square inch of sound, funneling it down into the eardrum. A person in the audience of an auditorium collects about two square inches of the sound wave, that's just about 0.00017 percent of the total sound emitted by the central cluster loud speaker. This tiny fraction of sound is called the "direct sound" because it goes directly from the loud speaker to the listeners' ears. (Figure-1).
If 1,000 people are in the audience, their combined ears collect only 0.17 percent of the direct sound emitted by the loud speaker. The rest of the sound, the other 99.83 percent of the sound, is called "indirect sound". What happens to all this indirect sound is what auditorium acoustics is all about. If the indirect sound is neglected or mishandled, the auditorium will sound bad, and if it is well handled, the auditorium will sound good.
To recap, auditorium design or renovation can be understood to involve three consecutive areas of expertise. The architect designs a building that is attractive, comfortable and allows people to see what is going on. The sound contractor supplies a sound system to the auditorium that makes a direct sound loud enough so people can hear what is going on. However, nearly all of the sound generated by the sound equipment misses its intended target, the ears of the people. Picking up and handling the stray sound is the responsibility of the acoustical engineer. How it is collected and processed makes all the difference between a good- and a bad-sounding auditorium.
Noise blocks our ability to hear
The auditorium is meant for understanding speech. It should be kept quiet so the people can hear and understand what is being said. Speech heard in the auditorium should be comfortably loud and crystal clear. Noise destroys sonic clarity. We have all seen photos taken in a fog. The general clatter in a hall from air conditioning to feet shuffling through the aisles can create a continuous din, a noise floor that seems to white out, haze over and block out the detain in an otherwise perfectly fine presentation. We have also seen photos taken on a clear day but blurred by a moving camera. Similarly, noise such as echo and reverberation can act as a blurring agent that makes it difficult to even make out what sound is actually there. These are the two kinds of noise. The fairly continuous din of extraneous noise is called "background" noise. The echo and reverberation of sound emitted from the loudspeaker is called "acoustic" noise. (Figure-2).
The ability to hear and understand depends on the "signal to noise" ratio. We want as much direct signal as is comfortable to receive and as little noise as possible. It would seem that if the noise is a little too loud then simply turning up the volume of the direct signal, the loudspeaker, should solve the problem. This doesn't work very well. Loud sound is uncomfortable. Loud sound does improve the fairly constant background noise to signal ratio. Loud sound does not improve the acoustic noise to signal ratio because the loudness of the acoustic noise depends directly on the loudness of the loudspeaker.
Also there is a context factor. People expect to hear a conversational style lecture at conversational sound levels (60 dB-A), a quiet voice at quiet voice levels (40 dB-A) and a raised voice at a raised voice level (70 dB-A). Cranking up the sound throws the presentation off, whereby the loudness is out of context with the lecturer's action --it's simply not natural.
For good intelligibility, there will be at least 20 dB between the quietest parts of the desirable signal and the background noise --since the more quiet parts of speech are easily in the 40 dB-A range and less. Background noise levels in a good auditorium will be as low as 20 dB-A. Also, there should be at least 10 dB between the signal and the acoustic background noise.
Background noise
Background noise is all the sounds one hears when the lecturer is not saying something. There are three types of background noise. Just sit and listen in most any meeting space and you can distinguish operational system noise, intruding outside noise and self-generated audience noise. In order to achieve a strong signal to background noise, the background noise has to be reduced to as quiet as possible.
The operating system includes all things that operate in order to accommodate the occupancy of the auditorium. Here we have the noise from systems that handle electricity, water and air in the building. They include the hum of lighting ballasts, the hiss and hum of the sound system, overhead circulation fan motor hum, video projector fans, air-conditioning noise and water pipes, both fresh water and wastewater. (Figure-3). Other systems sounds include the more intermittent operation of a dishwasher, garbage disposal, refrigerators, space heaters, toilet, faucet shut-off, watering, water hammer and thermal expansion and utility devices such as the copy machine, coke machine and cold water drinking fountain. The air-conditioning system is usually a strong contributor of noise, piping turbulent air and fan noise into the room through every air supply and return opening.
Intruding outside noise is conducted into the auditorium through the windows, doors, room and walls of the building. Traffic noise penetrates inside, in from the street and down from overhead planes. Parking-lot noise --driving, starting, door slamming and sidewalk conversations --contribute to intruding noise. Rain and wind can cause noise by hammering and scraping on the building. Outdoor stationary equipment such as heat exchangers and sprinklers cause noise. Even HVAC units mounted on the rooftop generate noise that can come in through the roof and upper windows, let alone shake the structural beams of the building. Activities in other parts of the building get into the auditorium by passing directly through the walls but also by simply traveling in the air, down corridors, under doors and through air-conditioning ductwork, room to room.
Self-generated audience noise also raises the noise within the auditorium. Here we have the rustle of paper, books, coats and clothes, shoe scuffing, candy wrappers, kids talking and parents hushing, coughing and sneezing, baby shouts, whining and eventually crying. Noise is generated even when people breathe and when they make little noises of agreement and appreciation and whisper to each other. To illustrate, a person trying to stand absolutely still, breathing as shallowly as possible still generates enough noise to register 20 dB-A at a distance of 10 feet.
There is a symbiotic effect of background noise. Some noise begets more noise. The quiet of a library provides testimony to this effect. It starts quiet and stays quiet all day. When the background noise is at a raised level, people feel that they too can make a little noise and no one will notice. But multiple this by 1,000 people and we have a significant increase in people-generated noise. This then results in a further raised noise floor and, once again, it seems easy for people to make just a little more noise. This spiraling effect can create a very noisy auditorium, full of disruption and inattention. An auditorium whose background noise level starts in the low 20 dB-A range stays quiet when the audience arrives.
Acoustic noise, echoes and reverberation
Sound expands away from the loud speaker. Most of what is created is not directly heard but goes past the audience and begins reflecting around the hall. If a reflection is strong and we know where it comes from, it is called an echo. If we hear many reflections at one time from seemingly no special direction, it is called reverberation.
Generally, any echo is bad. In addition, and to put it simply, loud reverberation is bad. But quiet reverberation can be interesting, if it is in limited doses. Both reverberation and echoes degrade the perception of timing in the material being presented. Strong echoes are disorienting to the timing aspect of speech or music, like trying to be coordinated in a disco strobe dance floor. It is not unusual for echoes to bother the performer more than anyone else in the auditorium. Echoes usually bounce off the back wall of the auditorium and because the person on stage is farthest from the back wall, the echo for the performer is the most delayed. And it is most important that the performer does not suffer disorientation due to echoes. We cannot forget Pavarotti walking off the stage of a large hall filled with people because the echo was so strong that he couldn't sing --but certainly, as we understand acoustics, we can understand and forgive.
Reverberation is the ongoing part of sound in a large hall that gradually decays away, a totally chaotic lingering presence of a previous direct sound, a sonic afterglow, a remembrance. Loud reverberation upsets the timing of sequential sonic events by blurring everything together. It is especially detrimental to speech and music in small hard-surfaced rooms. However, it can also be great personal fun, as in singing in the shower, but, in this case, the singer and the listener are one and there are no concerns for improving the communication.
Quiet reverberation can contribute to the feeling that a larger-than-life experience is taking place. It adds a dramatic flair of importance to speech. It is an essential accompanist to acoustic music sources as orchestra, ensemble, choir and organ. Reverberation generally ruins the presentation of modern electronic bands.
There are three aspects of reverberation to be understood. Onset time delay is the time between the direct signal is heard and the reverberation begins to be heard. The second is how loud the reverberation becomes. The third is how long the reverberation lasts or can be heard; the "reverb time" is officially the number of seconds it takes for sound to die down a full 60 dB. Reverberation in an auditorium that is used for speech, lectures and talks should have one-third second onset time delay, be at least 10 dB-A quieter than the direct signal and have a reverb time die out within 1.25 seconds.
If reverberation builds up too quickly it competes with the clear perception of the sequence of sounds that make up speech. A short reverberation onset time will fill the essential quiet moment that exists between and delineates sequential sonic events. The introduction of each new sound is blurred by the upwelling presence of the old sound. Speaking more slowly can help this situation, but forced slow speaking is a stopgap measure at best. Acoustically slurred speech is very difficult to understand. The time delay for the onset of reverberation should be about one-third of a second. Background noise is best if kept at least 20dB below the sound levels of speech. People speak at a rate of about three separate sounds per second. Some languages speak more slowly and others more quickly; auditorium acoustics have to be designed for the kind of speech that takes place in them.
The loudness of the reverberation is important, at least 10 dB-A below the level of direct speech will create reasonably clear speech. (Figure-4). A reverb level of 10 dB-A below the direct signal is very desirable. The loudness of the reverb changes the feeling of the auditorium. A warm, cozy, personal chatauqua style auditorium will have a large difference between direct and reverb levels, as much as 18 dB-A. A cold, impersonal, more political rally sounding auditorium will have a lower difference, possible as little as 5 dB-A.
Finally the length of time the reverberation remains audible is to be adjusted. Generally large rooms for speech are allowed reverb times of 1.5 seconds. Smaller auditoriums and more intimate sounding rooms should have reverb times as low as 0.9 seconds. The personal, conversational chatauqua style auditorium, growing popular in the world of broadcast TV church worship, will have reverb times as low as 0.7 seconds.
These three reverb factors are generally the same for auditoriums used for speech, plays and modern music. More traditional music tends to sound better with longer reverb onset delay times, louder reverb levels and longer reverb decay times. Some auditoriums are built to support a varied venue, from speech and plays to operas and symphonies. They have adjustable acoustics: reflecting and absorbing panels that are moved, exposed or hidden to independently adjust the three factors of reverberation.
An old saying: Look before you leap
The auditorium is a purpose-built hall, built for audition, listening. Before it can be designed, the architect has to understand what the large hall is to be used for. Before the sound contractor can specify the sound system, the purpose of the hall must be understood. Before the acoustical engineer can bring a voice to the auditorium, the feeling and style of presentations intended for the hall has to be understood. Voicing the auditorium means deciding what to do with 99 percent of the sound, generated by the loudspeakers but not directly heard by the audience. A bright and beautiful looking auditorium will attract people. But the quiet, good-sounding auditorium will keep them coming back.
Acoustics
The science that studies the waves that are conducted through matter due to the motion of the matter. Usually air is the material that most people think of when it comes to acoustic waves. But acoustic waves exist in all matter. Architectural acoustics, is the study of acoustics when the air is contained in a room. Church acoustics is a sub-division of architectural acoustics..
Sound (waves)
Pressure fluctuations in the air that are heard when an acoustic wave passes by. They are usually caused by objects in the air that quickly change position or a stream of air that quickly changes position. Sound escapes away from the sound source as an expanding spherical wave that travels at the speed of 1130 feet per second, traveling about 1 1/8th of a foot each one thousandths of a second (millisecond)..
Sound Level
The measure of the strength of sound. Units are decibels (dB) and usually measured with a dB meter. The threshold of quiet sound is zero dB and the onset of painful sound is 100 dB. Conversations are at 50 dB, whispers at 30 dB and shouting is 70 dB. When the sound strength of something doubles, it increases by 3 dB, or halved, it drops by 3 dB.
Loudness
The apparent strength of the sound to the listener. A change in 1 dB is just barely noticed as a change in loudness. Something twice as loud is actually 10 dB stronger, (10 times stronger). Something half as loud is 10 dB weaker, (1/10th as strong).
Direct Sound (direct signal)
The part of a sound wave that travels directly along the line of sight path between the speaker or sound source and the listener. The dry or actual sound.
Reflections
Sound waves that strike a surface and bounce off are reflected sounds. They bounce off the wall, changing directions but keeping the same angle off the wall as they had when they approached the wall.
Early Reflections
Reflections that are heard within 1/20 of a second of the direct sound are called early reflections. Early reflections cannot be distinguished from direct signals, they merge with the direct sound to form one composite sound. This combining effect can cause the sound of the direct signal to change in tonal characteristics and apparent direction.
Late reflections (Echoes)
A distinct reflection that arrives at the listener later than 1/20th of a second after the direct sound is heard. The listener can identify from where an echo comes. An echo does not change the tonal characteristics of the direct sound.
Flutter Echo
This type of echo is most easily heard as one claps their hands out in front of them, while standing in a hallway. The sound "zings" and it's tone depends on how many times a second the reflection passes by the listener's head. In a hall 8' wide, the clap will expand out, hit the wall and return 143 times a second and the zing will sound like a 143 Hz buzzy tone. Not a real sound, just a pseudo-tone.
Reverberation
For sound in a large room, reverberation begins at about 1/5 second following the direct sound. It is due to the accumulation of many reflections, compounding one upon the other, so much that the sound no longer seems composed of echoes but rather just a sound of noise, a din of chaos that has no discrete direction and no discrete timing.
Diffusion
Reflections off of a non flat surface that causes the sound wave to become more quickly disorganized than if off a flat surface is a diffusive surface. Diffusion decreases the time it takes for echoes to become converted to reverberation. The beautiful gothic churches of the old world have very diffusive or sound scattering surfaces. That is part of the sonic beauty of those spaces.
Decay
The dying out of sound. Usually referring to the steady decline in the loudness of the reverberation.
Decay Rate (RT-60)
The time (in seconds) it takes for reverberation to change from very loud to imperceptibly quiet, a total sound level difference of 60 dB. For a living room the RT-60 might be 1 second but in a gym, it might be 4 seconds.
Absorption
The loss of sound energy that occurs when the sound wave strikes a fibrous surface. The fibers provide acoustic friction for the sound wave. The wave does not slow down due to the friction, it keeps it's same speed but it does lose energy and get quieter.
NRC Rating
(Noise Reduction Coefficient) A rating for absorption. It gives the % efficiency for a surface to absorb sound. If a surface is 30% absorptive, then only 70% of the incident sound is reflected back into the room.
Noise (Background Noise)
The unwanted, undesirable and usually interfering sounds present in a listening space, typically due to an air conditioner or other conversations.
Noise Floor
The strength of the background noise, measured in dB. It is difficult to understand what is being said in a room with a high noise floor.
Signal-to-Noise Ratio (S/N ratio)
The difference in sound level (dB) between the desired sound and the noise floor.
Articulation
The clarity of a sound, particularly a message conveyed by sound, such that it can be easily and completely understood. A slurred sound may be well heard but the message it carries may still not be well understood, it is inarticulate. Also, a clear and distinct sound may be drowned out by a nearby louder noise, rendering the message not understandable, inarticulate. Echoes also cause articulation problems. Articulation is most often measured in some form of a desired signal to unwanted noise ratio.
Intelligibility
A measure of the clarity of sound based on the comprehension of the message being conveyed by sound. A "cat, bat, tat, rat... type of recognition test. The conversational version of Articulation.
Bright/Lively
The condition of sound in which there is an abundance of treble range reflections giving the feeling of "brightness" or "liveliness" to the sound. Sound in a tile bathroom or kitchen is bright. Too much can seem harsh and irritating.
Dark/Dead
The condition of sound in a room when there is a lack of reflections and a lack of reverberance. Too much can seem lack-luster and uneasy feeling.
Boomy
The condition of sound in a room when the lower frequencies, particularly the male voice range is excessively reverberant.
Psychoacoustics
The study and science of how the human comprehends and makes sense out of the sounds they hear. The difference between an early reflection and a late (echo) reflection, is an example of psychoacoustics. The blending of the early reflections with the direct sound is another.
Audiology
The science and practice of amplifying or otherwise improving how well a person hears sound.
Frequency (Hertz, Hz, cps)
A single sound pulse as from a fire cracker has sound energy but no tone. Tones are sounds that come from voices or instruments which have a repetitive pressure pulse characteristic. The number of repeat times per second that a sound has is called it's frequency. It's unit of measurement is cycles per second (cps) also called Hz (Hertz). Similar to pitch in musical terms.
Sound Spectrum
The sound level measured at different frequencies. Most tones are composed of more than one frequency, a combination of frequencies, as in a musical chord. The sound spectrum would measure the strength of each frequency and display that graph as a plot of Sound Level vs. Frequency, also known as a sound spectrum. The "color" of sound is used as emphasis in the spectrum.
Sonic Color
The shift in emphasis of a complex sound within it's spectral range. A neutral color is the preferred natural sound but sometimes sound can have a warm color, an emphasis on lower frequencies or a cold color, an emphasis on higher frequencies or a nasal color, an emphasis on midrange frequencies.
Ultrasonics
Sound whose frequency range is above that of human hearing, above 20,000 Hz.
Infrasonics
Sound whose frequency range is below that of human hearing, below 20 Hz.
Octave
Sound that exists within a limited frequency range, between a lower set frequency and a set upper frequency. The difference between the lower and upper frequency is specified to be equal to the lower frequency. The octave sequence for the note "C" starts at 31 Hz and continues thru 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1k Hz, 2k Hz, 4k Hz, 8k Hz and ends at 16k Hz. (k = thousand).
Voicing
The process of defining the desirable condition of sound in an acoustic space. It integrates the direct, early and late reflections with the reverberation, including a sense of timing and direction for each into an appropriate and desirable acoustic condition for the listener. It combines both the art and science of sound. It requires an understanding of the purpose to be served by each acoustic space. As an art form, it recognizes the aesthetic side of sound, the impression that most people prefer to have of each particular type of sound that exists in some particular place. As a science, it is based on psychoacoustics.
Acoustician
An acoustical engineer who is trained and experienced in voicing rooms.
Acoustical Engineer
One formally educated, experienced in the science and practice of acoustics.
Sound Engineer
Someone trained in setting up microphones and speakers.
Acoustic Contractor
Someone trained and experienced in installing acoustic tiles and wall panels.
Acoustic Consultant
Someone, not formally trained, experienced in providing acoustical services.
Acoustic Designer
Someone, not formally trained, who prepares blueprints for acoustic projects.
Sound Designer
One who envisions and directs the way sound plays out of a stage..
Auditorium Acoustics 101:
The Quieter, the Better
Let's start with the basics. The architect designs a great looking and comfortable auditorium. The sound contractor installs a great looking sound system. The people attend the grand opening and are impressed with what they see, but they have gathered for more than a dazzling display of architecture, lighting, electronics, carpets, glass, surface textures and paint. They have come to be in an auditorium, a place to hear and, moreover, a place to listen to and learn from the lecture or, as the case may be, the sermon. The outer beauty of an auditorium is recognized by how it looks, but the inner more lasting beauty of the auditorium is truly known by how it sounds. And with this we mark the beginning of our journey into auditorium acoustics.
Lots of sound, but little is heard
A sound wave starts at the loud speaker, which is suspended high overhead in the front of the hall. Seated way below, are the many people who came to hear that sound. The greater the size of the audience, the farther from the speaker they have to sit. An audience of 1,000 people would occupy about 8,000 square feet of floor space. A member of that audience typically might be seated some 50 feet away from the loudspeaker. The sound wave emitted by the loudspeaker spreads out in the shape of an expanding quarter sphere. By the time this wave reaches the audience, it has expanded out to a radius of about 50 feet. It has spread out over a quarter sphere surface area of 7,850 square feet or about 1.13 million square inches.
Each ear of a person collects about one square inch of sound, funneling it down into the eardrum. A person in the audience of an auditorium collects about two square inches of the sound wave, that's just about 0.00017 percent of the total sound emitted by the central cluster loud speaker. This tiny fraction of sound is called the "direct sound" because it goes directly from the loud speaker to the listeners' ears. (Figure-1).
If 1,000 people are in the audience, their combined ears collect only 0.17 percent of the direct sound emitted by the loud speaker. The rest of the sound, the other 99.83 percent of the sound, is called "indirect sound". What happens to all this indirect sound is what auditorium acoustics is all about. If the indirect sound is neglected or mishandled, the auditorium will sound bad, and if it is well handled, the auditorium will sound good.
To recap, auditorium design or renovation can be understood to involve three consecutive areas of expertise. The architect designs a building that is attractive, comfortable and allows people to see what is going on. The sound contractor supplies a sound system to the auditorium that makes a direct sound loud enough so people can hear what is going on. However, nearly all of the sound generated by the sound equipment misses its intended target, the ears of the people. Picking up and handling the stray sound is the responsibility of the acoustical engineer. How it is collected and processed makes all the difference between a good- and a bad-sounding auditorium.
Noise blocks our ability to hear
The auditorium is meant for understanding speech. It should be kept quiet so the people can hear and understand what is being said. Speech heard in the auditorium should be comfortably loud and crystal clear. Noise destroys sonic clarity. We have all seen photos taken in a fog. The general clatter in a hall from air conditioning to feet shuffling through the aisles can create a continuous din, a noise floor that seems to white out, haze over and block out the detain in an otherwise perfectly fine presentation. We have also seen photos taken on a clear day but blurred by a moving camera. Similarly, noise such as echo and reverberation can act as a blurring agent that makes it difficult to even make out what sound is actually there. These are the two kinds of noise. The fairly continuous din of extraneous noise is called "background" noise. The echo and reverberation of sound emitted from the loudspeaker is called "acoustic" noise. (Figure-2).
The ability to hear and understand depends on the "signal to noise" ratio. We want as much direct signal as is comfortable to receive and as little noise as possible. It would seem that if the noise is a little too loud then simply turning up the volume of the direct signal, the loudspeaker, should solve the problem. This doesn't work very well. Loud sound is uncomfortable. Loud sound does improve the fairly constant background noise to signal ratio. Loud sound does not improve the acoustic noise to signal ratio because the loudness of the acoustic noise depends directly on the loudness of the loudspeaker.
Also there is a context factor. People expect to hear a conversational style lecture at conversational sound levels (60 dB-A), a quiet voice at quiet voice levels (40 dB-A) and a raised voice at a raised voice level (70 dB-A). Cranking up the sound throws the presentation off, whereby the loudness is out of context with the lecturer's action --it's simply not natural.
For good intelligibility, there will be at least 20 dB between the quietest parts of the desirable signal and the background noise --since the more quiet parts of speech are easily in the 40 dB-A range and less. Background noise levels in a good auditorium will be as low as 20 dB-A. Also, there should be at least 10 dB between the signal and the acoustic background noise.
Background noise
Background noise is all the sounds one hears when the lecturer is not saying something. There are three types of background noise. Just sit and listen in most any meeting space and you can distinguish operational system noise, intruding outside noise and self-generated audience noise. In order to achieve a strong signal to background noise, the background noise has to be reduced to as quiet as possible.
The operating system includes all things that operate in order to accommodate the occupancy of the auditorium. Here we have the noise from systems that handle electricity, water and air in the building. They include the hum of lighting ballasts, the hiss and hum of the sound system, overhead circulation fan motor hum, video projector fans, air-conditioning noise and water pipes, both fresh water and wastewater. (Figure-3). Other systems sounds include the more intermittent operation of a dishwasher, garbage disposal, refrigerators, space heaters, toilet, faucet shut-off, watering, water hammer and thermal expansion and utility devices such as the copy machine, coke machine and cold water drinking fountain. The air-conditioning system is usually a strong contributor of noise, piping turbulent air and fan noise into the room through every air supply and return opening.
Intruding outside noise is conducted into the auditorium through the windows, doors, room and walls of the building. Traffic noise penetrates inside, in from the street and down from overhead planes. Parking-lot noise --driving, starting, door slamming and sidewalk conversations --contribute to intruding noise. Rain and wind can cause noise by hammering and scraping on the building. Outdoor stationary equipment such as heat exchangers and sprinklers cause noise. Even HVAC units mounted on the rooftop generate noise that can come in through the roof and upper windows, let alone shake the structural beams of the building. Activities in other parts of the building get into the auditorium by passing directly through the walls but also by simply traveling in the air, down corridors, under doors and through air-conditioning ductwork, room to room.
Self-generated audience noise also raises the noise within the auditorium. Here we have the rustle of paper, books, coats and clothes, shoe scuffing, candy wrappers, kids talking and parents hushing, coughing and sneezing, baby shouts, whining and eventually crying. Noise is generated even when people breathe and when they make little noises of agreement and appreciation and whisper to each other. To illustrate, a person trying to stand absolutely still, breathing as shallowly as possible still generates enough noise to register 20 dB-A at a distance of 10 feet.
There is a symbiotic effect of background noise. Some noise begets more noise. The quiet of a library provides testimony to this effect. It starts quiet and stays quiet all day. When the background noise is at a raised level, people feel that they too can make a little noise and no one will notice. But multiple this by 1,000 people and we have a significant increase in people-generated noise. This then results in a further raised noise floor and, once again, it seems easy for people to make just a little more noise. This spiraling effect can create a very noisy auditorium, full of disruption and inattention. An auditorium whose background noise level starts in the low 20 dB-A range stays quiet when the audience arrives.
Acoustic noise, echoes and reverberation
Sound expands away from the loud speaker. Most of what is created is not directly heard but goes past the audience and begins reflecting around the hall. If a reflection is strong and we know where it comes from, it is called an echo. If we hear many reflections at one time from seemingly no special direction, it is called reverberation.
Generally, any echo is bad. In addition, and to put it simply, loud reverberation is bad. But quiet reverberation can be interesting, if it is in limited doses. Both reverberation and echoes degrade the perception of timing in the material being presented. Strong echoes are disorienting to the timing aspect of speech or music, like trying to be coordinated in a disco strobe dance floor. It is not unusual for echoes to bother the performer more than anyone else in the auditorium. Echoes usually bounce off the back wall of the auditorium and because the person on stage is farthest from the back wall, the echo for the performer is the most delayed. And it is most important that the performer does not suffer disorientation due to echoes. We cannot forget Pavarotti walking off the stage of a large hall filled with people because the echo was so strong that he couldn't sing --but certainly, as we understand acoustics, we can understand and forgive.
Reverberation is the ongoing part of sound in a large hall that gradually decays away, a totally chaotic lingering presence of a previous direct sound, a sonic afterglow, a remembrance. Loud reverberation upsets the timing of sequential sonic events by blurring everything together. It is especially detrimental to speech and music in small hard-surfaced rooms. However, it can also be great personal fun, as in singing in the shower, but, in this case, the singer and the listener are one and there are no concerns for improving the communication.
Quiet reverberation can contribute to the feeling that a larger-than-life experience is taking place. It adds a dramatic flair of importance to speech. It is an essential accompanist to acoustic music sources as orchestra, ensemble, choir and organ. Reverberation generally ruins the presentation of modern electronic bands.
There are three aspects of reverberation to be understood. Onset time delay is the time between the direct signal is heard and the reverberation begins to be heard. The second is how loud the reverberation becomes. The third is how long the reverberation lasts or can be heard; the "reverb time" is officially the number of seconds it takes for sound to die down a full 60 dB. Reverberation in an auditorium that is used for speech, lectures and talks should have one-third second onset time delay, be at least 10 dB-A quieter than the direct signal and have a reverb time die out within 1.25 seconds.
If reverberation builds up too quickly it competes with the clear perception of the sequence of sounds that make up speech. A short reverberation onset time will fill the essential quiet moment that exists between and delineates sequential sonic events. The introduction of each new sound is blurred by the upwelling presence of the old sound. Speaking more slowly can help this situation, but forced slow speaking is a stopgap measure at best. Acoustically slurred speech is very difficult to understand. The time delay for the onset of reverberation should be about one-third of a second. Background noise is best if kept at least 20dB below the sound levels of speech. People speak at a rate of about three separate sounds per second. Some languages speak more slowly and others more quickly; auditorium acoustics have to be designed for the kind of speech that takes place in them.
The loudness of the reverberation is important, at least 10 dB-A below the level of direct speech will create reasonably clear speech. (Figure-4). A reverb level of 10 dB-A below the direct signal is very desirable. The loudness of the reverb changes the feeling of the auditorium. A warm, cozy, personal chatauqua style auditorium will have a large difference between direct and reverb levels, as much as 18 dB-A. A cold, impersonal, more political rally sounding auditorium will have a lower difference, possible as little as 5 dB-A.
Finally the length of time the reverberation remains audible is to be adjusted. Generally large rooms for speech are allowed reverb times of 1.5 seconds. Smaller auditoriums and more intimate sounding rooms should have reverb times as low as 0.9 seconds. The personal, conversational chatauqua style auditorium, growing popular in the world of broadcast TV church worship, will have reverb times as low as 0.7 seconds.
These three reverb factors are generally the same for auditoriums used for speech, plays and modern music. More traditional music tends to sound better with longer reverb onset delay times, louder reverb levels and longer reverb decay times. Some auditoriums are built to support a varied venue, from speech and plays to operas and symphonies. They have adjustable acoustics: reflecting and absorbing panels that are moved, exposed or hidden to independently adjust the three factors of reverberation.
An old saying: Look before you leap
The auditorium is a purpose-built hall, built for audition, listening. Before it can be designed, the architect has to understand what the large hall is to be used for. Before the sound contractor can specify the sound system, the purpose of the hall must be understood. Before the acoustical engineer can bring a voice to the auditorium, the feeling and style of presentations intended for the hall has to be understood. Voicing the auditorium means deciding what to do with 99 percent of the sound, generated by the loudspeakers but not directly heard by the audience. A bright and beautiful looking auditorium will attract people. But the quiet, good-sounding auditorium will keep them coming back.
ELECTRICAL NOTES
Electrical Notes:
COULUMB (C)
- The SI unit of electric charge equal to the quantity of electricity transferred along the conductor by a current of one ampere in one second
WATT (W)
- the SI unit equal to one joule per second or to the power represented by a current of one ampere flowing across a potential difference of one volt
W= V x A
WATTAGE
- an amount of power especially the power required to operate an electrical device or appliance, expressed in watts
KILOWATT (kW)
- a unit of power equal to 1,000 watts
KILOWATT-HOUR (kWh)
- a unit of energy transferred or expanded by one kilowatt in one hour a common unit of electric power consumption
ELECTROMOTIVE FORCE (emf)
- the energy per unit charge available for conversion from a chemical, mechanical or other form of energy into electrical energy or vice versa in a conversion devise as a battery, generator or a motor
POTENTIAL DIFFERENCE
- the voltage difference between two points that represents the work involved in the transfer of a unit charge from one point to the other
POTENTIAL
- the work required to move a unit charge from a reference point to a designed point
VOLTAGE
- potential difference or electromotive force expressed in volts: analogous to pressure in water flow
VOLT (V)
- the SI unit of potential difference and electromotive force, defined as the difference of electric potential between two points of a conductor carrying a constant current of one ampere, when the power dissipated between the points is equal to one watt
CURRENT
- the rate of flow of electric charge in a circuit per unit time measured in amperes
AMPERE (A)
- the basic SI unit of electric current, equivalent to a flow of one coulomb per second or to the steady current produced by one volt applied to one resistance of one ohm
AMPERAGE
- the strength of an electric current measured or expressed in amperes: analogous to the rate of water flow
RESISTANCE (R)
- the opposition of a conductor to the flow of current, causing some of the electric energy to be transformed into heat and usually measured in ohms
OHM
- the SI unit of electrical resistance, equal to the resistance of a conductor in which a potential difference of one volt produces a current of one ampere
OHM’S LAW
- that law that for any circuit the electric current is directly proportional to the voltage and inversely proportional to the resistance
I= V/R
JOULE’S LAW
- the principle that the rate of production of heat by direct current is directly proportional to the resistance of the circuit and to the square of the current
RESISTIVITY
- the resistance per unit length of a substance with a cross sectional area. Also called specific resistance
CONDUCTIVITY
- a measure of the ability of a substance to conduct electric current, equal to the reciprocal of the resistivity of the substance. Also called specific conductance
CIRCUIT
- the complete path of an electric current including the source of electric energy
SERIES
- an arrangement of components in an electric circuit in which the same current flows through each component in turn without branching
PARALLEL
- the arrangement of components in an electric circuit in which all positive terminals are connected to a second conductor, the same voltage being applied to each component
BATTERY
- a group of two or more cells connected together to produce electric current
CELL
- a device for converting chemical into electric energy usually consisting of a receptacle with electrodes in an electrolyte. Also called electric cell
ELECTROLYTE
- a non metallic conducting medium in which current is carried by the movement of ions
ELECTRODE
- a conductor through which a current enters or leaves a non metallic medium
ANODE
- the negative terminal of a primary cell or storage battery
CATHODE
- the positive terminal of a primary cell or storage battery
GENERATOR
- a machine that converts mechanical energy into electric energy
ALTERNATOR - a generator for producing alternating current
ELECTRIC MOTOR
- a machine that converts electric power into mechanical energy
ARMATURE
-the main current-carrying winding of a motor or generator in which electromotive force is induced
DIRECT CURRENT (DC)
- an electric current in one direction only having a magnitude that does not vary or varies only slightly
ALTERNATING CURRENT (AC)
- an electric current that reverses direction at regularly recurring intervals, having a magnitude that varies in a sinusoidal manner
VOLT AMPERE (VA)
- a unit of electric measurement equal to the product of one volt and one ampere, equivalent to one watt for direct current system and a unit of apparent power for alternating current systems
TRANSFORMER
- an electric device consisting of two or more winding wound on the same core, which employs the principle of mutual induction to convert variations of alternating current in a primary circuit into variations of voltage and current in a secondary circuit
STEP-UP TRANSFORMER
- a transformer having fewer turns in the primary winding than in the secondary, serving to transform low voltage to high voltage
STEP-DOWN TRANSFORMER
- a transfer having a greater number of turns in the primary winding than in the secondary, serving to transform high voltage to low voltage
LINE VOLTAGE
- the voltage supplied by a power line, measured at the point of use
SERVICE CONDUCTOR
- any of several conductors extending from a main power line or transformer to the service equipment of a building
SERVICE
- the supply of utilities, as water, gas and electricity, required or demanded by the public
HIGH VOLATGE
- operated on power by or transmitting high voltage
SUBSTATION
- an auxiliary power station where electrical current is converted, as from DC to AC or where voltage is stepped up or down
SERVICE DROP
- the overhead portion of service conductors extending from the nearest utility pole to a building
SERVICE LATERAL
- the underground portion of service conductors extending from a main power line or transformer to a building
LINE DROP
- the decrease in voltage between two points on a power line, usually caused by resistance or leakage along the line
SERVICE ENTRANCE CONDUCTOR
- the portion of a service conductor extending from a service drop or service lateral to the service equipment of a building
WATT- HOUR METER
- a meter for measuring and recording the quality of electric power consumed with respect to time
TRANSFORMER VAULT
- a fire-rated room housing a transformer and auxiliary equipment for a large building, usually located on grade or below ground and ventilated directly to the outside air
SWITCHGEAR ROOM - a room containing the service equipment for a large building
SERVICE EQUIPMENT
- the equipment necessary for controlling, metering, and protecting the electric power supply to a building, located near the entrance of the service conductors and usually consisting of a main disconnect switch and secondary switch, fuses and circuit breakers
STANDBY GENERATOR
- a generator for providing emergency power during a power outage. Also called emergency generator
UNINTERRUPTIBLE POWER SUPPLY
- an emergency system designed to provide power automatically and instantaneously upon failure of the normal power supply
SWITCHBOARD
- one or a group of panels on which are mounted switches, over current devices, metering instruments, and buses for controlling and protecting a number of electric circuits called switchgear
UNIT SUBSTATION
- a free standing enclosure housing a disconnect switch, a step-down transformer and switchgear for a number of electric circuit
FEEDER
- any of the conductors extending from the service equipment to various distribution points in a building
WIRE
- a pliable metallic strand or twisted or woven assembly of such strands often insulated with a dielectric material and used as a conductor of electricity
CONDUCTOR - a substance, body or devise that conducts heat, sound or electricity
INSULATOR
- a material that is poor conductor of electricity used in operating or supporting conductors to prevent the undesired flow of current
CABLE - a single insulated conductor or a bound or sheathed combination of conductors insulated from one another
ARMORED CABLE
- electric cable consisting of two or more insulated conductors protected by flexible, helically wound metal wrapping. Also called BX
MINERAL ISULATED CABLE
- electric cable consisting of a tubular copper sheath containing one or more conductors embedded in a highly compressed, insulating refractory mineral
NON- METALLIC SHEATED CABLE
- electric cable consisting of two or more insulated conductors enclosed in a non- metallic, moisture resistant, flame retardant sheath. Also called ROMEX
COAXIAL CABLE
- a cable for transmitting high frequency telephone, digital or television signals consisting of an insulated conducting core
SHIELDED CABLE - an electric cable enclosed within a metallic sheath in order to reduce the effects of external electric or magnetic fields
CONDUIT - a tube, pipe or duct for enclosing and protecting electric wires or cable
RIGID METAL CONDUIT
- heavy-walled, tubular steel conduits joined by screwing directly into a threaded hub with locknuts and bushings
ELECTRICAL METAL TUBING (EMT)
- thin-walled, tubular steel conduit joined by compression or setscrew couplings
FLEXIBLE METAL CONDUIT
- flexible, helically wound metal conduit, used for connections to motors or other vibrating equipment. Also called Greenfield conduit
RACEWAY - a channel expressly designed to hold and protect electric wires and cables
SURFACE RACEWAY - a raceway designed to exposed installation in dry, non-hazardous, corrosive locations
MULTI- OUTLET ASSEMBLY - a surface mounted raceway designed to house the electrical wires for a circuit and a series of receptacles
DUCT - an enclosed runway for housing conductors or cables
BUS DUCT - a rigid metal housing for a group of buses insulted from each other and the enclosure. Also called busway
CABLE TRAY - an open metal framework for supporting insulated electrical conductors
BREAKDOWN VOLTAGE
- the minimum applied voltage at which a given insulator breaks down and permits current to pass
DIELECTRIC STRENGTH - the maximum voltage that can be applied to a given material without causing it to breakdown, usually expressed in volts or kilovolts per unit of thickness
DIELECTRIC - a non-conducting substance
JUNCTION BOX
- an enclosure for housing and protecting electric wires or cables that are joined together in connecting or branching electric circuits
KNOCKOUT - a panel in a casing or box that can readily be removed, as by punching, hammering or cutting to provide an opening into the interior
GROMMET - a rubber or plastic washer inserted in a hole in a metal part to prevent grounding of a wire passing through the hole
BUSHING - an insulating and protective lining for one or more conductors passing through a hole
UTILITY BOX - for lighting outlet and convenience outlet
PULL BOX - to facilitate pulling
OUTLET BOX - where cable ends
CUT OUT BOX - metal box with hinge & enclosure. House or fuse box
INSULATOR - used as supports and for additional protection for wires
GENERAL WIRING
RHW Moisture and heat resistance rubber Dry and wet locations
T Thermoplastic Dry locations
TW Moisture resistant thermoplastic Dry and wet locations
THHN Heat resistant thermoplastic Dry locations
THW Moisture & heat resistant thermoplastic Dry and wet locations
THWN Moisture & heat resistant thermoplastic Dry and wet locations
XHHW Moisture & heat resistant cross linked Dry and wet locations
SA Silicone asbestos Dry locations
AVA Asbestos and varnished cambric Dry locations only
CONDUIT FITTINGS:
1. elbow (long sweep)
2. tee
a. LB Condulets (angle & bended)
b. LR (angle to the right)
c. TF (tee front)
CONDUITS:
1. RIGID CONDUITS- cannot be bended
metal- RSC/ EMT
non-metal- PVC
2. FLEXIBLE
metal- BX
COULUMB (C)
- The SI unit of electric charge equal to the quantity of electricity transferred along the conductor by a current of one ampere in one second
WATT (W)
- the SI unit equal to one joule per second or to the power represented by a current of one ampere flowing across a potential difference of one volt
W= V x A
WATTAGE
- an amount of power especially the power required to operate an electrical device or appliance, expressed in watts
KILOWATT (kW)
- a unit of power equal to 1,000 watts
KILOWATT-HOUR (kWh)
- a unit of energy transferred or expanded by one kilowatt in one hour a common unit of electric power consumption
ELECTROMOTIVE FORCE (emf)
- the energy per unit charge available for conversion from a chemical, mechanical or other form of energy into electrical energy or vice versa in a conversion devise as a battery, generator or a motor
POTENTIAL DIFFERENCE
- the voltage difference between two points that represents the work involved in the transfer of a unit charge from one point to the other
POTENTIAL
- the work required to move a unit charge from a reference point to a designed point
VOLTAGE
- potential difference or electromotive force expressed in volts: analogous to pressure in water flow
VOLT (V)
- the SI unit of potential difference and electromotive force, defined as the difference of electric potential between two points of a conductor carrying a constant current of one ampere, when the power dissipated between the points is equal to one watt
CURRENT
- the rate of flow of electric charge in a circuit per unit time measured in amperes
AMPERE (A)
- the basic SI unit of electric current, equivalent to a flow of one coulomb per second or to the steady current produced by one volt applied to one resistance of one ohm
AMPERAGE
- the strength of an electric current measured or expressed in amperes: analogous to the rate of water flow
RESISTANCE (R)
- the opposition of a conductor to the flow of current, causing some of the electric energy to be transformed into heat and usually measured in ohms
OHM
- the SI unit of electrical resistance, equal to the resistance of a conductor in which a potential difference of one volt produces a current of one ampere
OHM’S LAW
- that law that for any circuit the electric current is directly proportional to the voltage and inversely proportional to the resistance
I= V/R
JOULE’S LAW
- the principle that the rate of production of heat by direct current is directly proportional to the resistance of the circuit and to the square of the current
RESISTIVITY
- the resistance per unit length of a substance with a cross sectional area. Also called specific resistance
CONDUCTIVITY
- a measure of the ability of a substance to conduct electric current, equal to the reciprocal of the resistivity of the substance. Also called specific conductance
CIRCUIT
- the complete path of an electric current including the source of electric energy
SERIES
- an arrangement of components in an electric circuit in which the same current flows through each component in turn without branching
PARALLEL
- the arrangement of components in an electric circuit in which all positive terminals are connected to a second conductor, the same voltage being applied to each component
BATTERY
- a group of two or more cells connected together to produce electric current
CELL
- a device for converting chemical into electric energy usually consisting of a receptacle with electrodes in an electrolyte. Also called electric cell
ELECTROLYTE
- a non metallic conducting medium in which current is carried by the movement of ions
ELECTRODE
- a conductor through which a current enters or leaves a non metallic medium
ANODE
- the negative terminal of a primary cell or storage battery
CATHODE
- the positive terminal of a primary cell or storage battery
GENERATOR
- a machine that converts mechanical energy into electric energy
ALTERNATOR - a generator for producing alternating current
ELECTRIC MOTOR
- a machine that converts electric power into mechanical energy
ARMATURE
-the main current-carrying winding of a motor or generator in which electromotive force is induced
DIRECT CURRENT (DC)
- an electric current in one direction only having a magnitude that does not vary or varies only slightly
ALTERNATING CURRENT (AC)
- an electric current that reverses direction at regularly recurring intervals, having a magnitude that varies in a sinusoidal manner
VOLT AMPERE (VA)
- a unit of electric measurement equal to the product of one volt and one ampere, equivalent to one watt for direct current system and a unit of apparent power for alternating current systems
TRANSFORMER
- an electric device consisting of two or more winding wound on the same core, which employs the principle of mutual induction to convert variations of alternating current in a primary circuit into variations of voltage and current in a secondary circuit
STEP-UP TRANSFORMER
- a transformer having fewer turns in the primary winding than in the secondary, serving to transform low voltage to high voltage
STEP-DOWN TRANSFORMER
- a transfer having a greater number of turns in the primary winding than in the secondary, serving to transform high voltage to low voltage
LINE VOLTAGE
- the voltage supplied by a power line, measured at the point of use
SERVICE CONDUCTOR
- any of several conductors extending from a main power line or transformer to the service equipment of a building
SERVICE
- the supply of utilities, as water, gas and electricity, required or demanded by the public
HIGH VOLATGE
- operated on power by or transmitting high voltage
SUBSTATION
- an auxiliary power station where electrical current is converted, as from DC to AC or where voltage is stepped up or down
SERVICE DROP
- the overhead portion of service conductors extending from the nearest utility pole to a building
SERVICE LATERAL
- the underground portion of service conductors extending from a main power line or transformer to a building
LINE DROP
- the decrease in voltage between two points on a power line, usually caused by resistance or leakage along the line
SERVICE ENTRANCE CONDUCTOR
- the portion of a service conductor extending from a service drop or service lateral to the service equipment of a building
WATT- HOUR METER
- a meter for measuring and recording the quality of electric power consumed with respect to time
TRANSFORMER VAULT
- a fire-rated room housing a transformer and auxiliary equipment for a large building, usually located on grade or below ground and ventilated directly to the outside air
SWITCHGEAR ROOM - a room containing the service equipment for a large building
SERVICE EQUIPMENT
- the equipment necessary for controlling, metering, and protecting the electric power supply to a building, located near the entrance of the service conductors and usually consisting of a main disconnect switch and secondary switch, fuses and circuit breakers
STANDBY GENERATOR
- a generator for providing emergency power during a power outage. Also called emergency generator
UNINTERRUPTIBLE POWER SUPPLY
- an emergency system designed to provide power automatically and instantaneously upon failure of the normal power supply
SWITCHBOARD
- one or a group of panels on which are mounted switches, over current devices, metering instruments, and buses for controlling and protecting a number of electric circuits called switchgear
UNIT SUBSTATION
- a free standing enclosure housing a disconnect switch, a step-down transformer and switchgear for a number of electric circuit
FEEDER
- any of the conductors extending from the service equipment to various distribution points in a building
WIRE
- a pliable metallic strand or twisted or woven assembly of such strands often insulated with a dielectric material and used as a conductor of electricity
CONDUCTOR - a substance, body or devise that conducts heat, sound or electricity
INSULATOR
- a material that is poor conductor of electricity used in operating or supporting conductors to prevent the undesired flow of current
CABLE - a single insulated conductor or a bound or sheathed combination of conductors insulated from one another
ARMORED CABLE
- electric cable consisting of two or more insulated conductors protected by flexible, helically wound metal wrapping. Also called BX
MINERAL ISULATED CABLE
- electric cable consisting of a tubular copper sheath containing one or more conductors embedded in a highly compressed, insulating refractory mineral
NON- METALLIC SHEATED CABLE
- electric cable consisting of two or more insulated conductors enclosed in a non- metallic, moisture resistant, flame retardant sheath. Also called ROMEX
COAXIAL CABLE
- a cable for transmitting high frequency telephone, digital or television signals consisting of an insulated conducting core
SHIELDED CABLE - an electric cable enclosed within a metallic sheath in order to reduce the effects of external electric or magnetic fields
CONDUIT - a tube, pipe or duct for enclosing and protecting electric wires or cable
RIGID METAL CONDUIT
- heavy-walled, tubular steel conduits joined by screwing directly into a threaded hub with locknuts and bushings
ELECTRICAL METAL TUBING (EMT)
- thin-walled, tubular steel conduit joined by compression or setscrew couplings
FLEXIBLE METAL CONDUIT
- flexible, helically wound metal conduit, used for connections to motors or other vibrating equipment. Also called Greenfield conduit
RACEWAY - a channel expressly designed to hold and protect electric wires and cables
SURFACE RACEWAY - a raceway designed to exposed installation in dry, non-hazardous, corrosive locations
MULTI- OUTLET ASSEMBLY - a surface mounted raceway designed to house the electrical wires for a circuit and a series of receptacles
DUCT - an enclosed runway for housing conductors or cables
BUS DUCT - a rigid metal housing for a group of buses insulted from each other and the enclosure. Also called busway
CABLE TRAY - an open metal framework for supporting insulated electrical conductors
BREAKDOWN VOLTAGE
- the minimum applied voltage at which a given insulator breaks down and permits current to pass
DIELECTRIC STRENGTH - the maximum voltage that can be applied to a given material without causing it to breakdown, usually expressed in volts or kilovolts per unit of thickness
DIELECTRIC - a non-conducting substance
JUNCTION BOX
- an enclosure for housing and protecting electric wires or cables that are joined together in connecting or branching electric circuits
KNOCKOUT - a panel in a casing or box that can readily be removed, as by punching, hammering or cutting to provide an opening into the interior
GROMMET - a rubber or plastic washer inserted in a hole in a metal part to prevent grounding of a wire passing through the hole
BUSHING - an insulating and protective lining for one or more conductors passing through a hole
UTILITY BOX - for lighting outlet and convenience outlet
PULL BOX - to facilitate pulling
OUTLET BOX - where cable ends
CUT OUT BOX - metal box with hinge & enclosure. House or fuse box
INSULATOR - used as supports and for additional protection for wires
GENERAL WIRING
RHW Moisture and heat resistance rubber Dry and wet locations
T Thermoplastic Dry locations
TW Moisture resistant thermoplastic Dry and wet locations
THHN Heat resistant thermoplastic Dry locations
THW Moisture & heat resistant thermoplastic Dry and wet locations
THWN Moisture & heat resistant thermoplastic Dry and wet locations
XHHW Moisture & heat resistant cross linked Dry and wet locations
SA Silicone asbestos Dry locations
AVA Asbestos and varnished cambric Dry locations only
CONDUIT FITTINGS:
1. elbow (long sweep)
2. tee
a. LB Condulets (angle & bended)
b. LR (angle to the right)
c. TF (tee front)
CONDUITS:
1. RIGID CONDUITS- cannot be bended
metal- RSC/ EMT
non-metal- PVC
2. FLEXIBLE
metal- BX
ROOM ACOUSTICS
ROOM ACOUSTICS
Sound Indoors – Acoustics of Room
• Sound in an enclosure radiates out from the source until it hits a surface that reflects or absorbs it
• If the source is continuous, a state of equilibrium will be reached
• Levels are constant throughout most spaces except at points very near the source (for a given source, the built-up or reverberant levels will be highest in a space with a few absorptive surfaces – lobby with marble walls/floors; in a space with large areas of sound absorbing materials, the levels will be lowest
1. Sound Absorption
• Materials varying sound absorption characteristics
Some absorb low frequency energy
Some absorb high frequency energy
Others absorb energy equally over a broad spectrum
• Mechanism of Absorption: 3 families of devices for sound absorption; all types absorb sound by changing sound energy to heat energy
Fibrous materials (Porous materials): absorption provided by a specific material depends on thickness, density, porosity, resistance to air flow (e.g. materials must be thick to absorb low frequency sounds effectively; suspending an acoustical ceiling tile a foot below the structure results in better broad band absorption than cementing the tile directly to the structure; “acoustic” paints with sand or walnut shells are useless as sound absorbers
Panel resonators: built with a membrane (thin plywood, linoleum in front of a sealed airspace); panel is set in motion by the alternating pressure of the impinging sound wave; sound energy is converted into heat through internal viscous damping; used where efficient low frequency absorption is required/ mid and high frequency absorption is unwanted; used in recording studios
Volume resonators
• Coefficient of Absorption (α): Knowing the amount of absorption at different frequencies for each material in a room is essential in designing the room acoustics
The absorption coefficient is the fraction of incident energy that is absorbed by a surface expressed as
α = Ia
Ii
Ii = incident energy, watts/cm2
Ia= absorbed energy, watts/cm2
α = absorption coefficient (no units)
Total absorption (A) provided by a surface (S) is expressed in sabins
A = Sα
A = Total absorption, sabins
S = Surface area, sq ft
α = Coefficient of absorption
6
Coefficients of General Building Materials and Furnishings
Coefficients for absorption in auditorium is shown for both empty and occupied seating conditions
• Many products are prefabricated for sound absorbing treatment (suspended ceilings/wall mounted treatments
• 3 kinds of custom-designed treatments that are often used in auditoriums/churches (the deep air space insures adequate low frequency performance
2. Noise Reduction by Absorption
• Noise levels in a room are highest for a given source if the room’s surfaces are primarily sound reflecting; lowest if there are large areas of sound absorbing materials (e.g. sound absorbing ceilings
3. Reflections
4. Reverberation
Sound Indoors – Acoustics of Room
• Sound in an enclosure radiates out from the source until it hits a surface that reflects or absorbs it
• If the source is continuous, a state of equilibrium will be reached
• Levels are constant throughout most spaces except at points very near the source (for a given source, the built-up or reverberant levels will be highest in a space with a few absorptive surfaces – lobby with marble walls/floors; in a space with large areas of sound absorbing materials, the levels will be lowest
1. Sound Absorption
• Materials varying sound absorption characteristics
Some absorb low frequency energy
Some absorb high frequency energy
Others absorb energy equally over a broad spectrum
• Mechanism of Absorption: 3 families of devices for sound absorption; all types absorb sound by changing sound energy to heat energy
Fibrous materials (Porous materials): absorption provided by a specific material depends on thickness, density, porosity, resistance to air flow (e.g. materials must be thick to absorb low frequency sounds effectively; suspending an acoustical ceiling tile a foot below the structure results in better broad band absorption than cementing the tile directly to the structure; “acoustic” paints with sand or walnut shells are useless as sound absorbers
Panel resonators: built with a membrane (thin plywood, linoleum in front of a sealed airspace); panel is set in motion by the alternating pressure of the impinging sound wave; sound energy is converted into heat through internal viscous damping; used where efficient low frequency absorption is required/ mid and high frequency absorption is unwanted; used in recording studios
Volume resonators
• Coefficient of Absorption (α): Knowing the amount of absorption at different frequencies for each material in a room is essential in designing the room acoustics
The absorption coefficient is the fraction of incident energy that is absorbed by a surface expressed as
α = Ia
Ii
Ii = incident energy, watts/cm2
Ia= absorbed energy, watts/cm2
α = absorption coefficient (no units)
Total absorption (A) provided by a surface (S) is expressed in sabins
A = Sα
A = Total absorption, sabins
S = Surface area, sq ft
α = Coefficient of absorption
6
Coefficients of General Building Materials and Furnishings
Coefficients for absorption in auditorium is shown for both empty and occupied seating conditions
• Many products are prefabricated for sound absorbing treatment (suspended ceilings/wall mounted treatments
• 3 kinds of custom-designed treatments that are often used in auditoriums/churches (the deep air space insures adequate low frequency performance
2. Noise Reduction by Absorption
• Noise levels in a room are highest for a given source if the room’s surfaces are primarily sound reflecting; lowest if there are large areas of sound absorbing materials (e.g. sound absorbing ceilings
3. Reflections
4. Reverberation
Subscribe to:
Posts (Atom)