Cover [PDF]

Standards [PDF]

Foreword [PDF]

Acknowledgements [PDF]

Dedication [PDF]

Contents [PDF]

Chapter 1 General

Chapter 2 Combinations of Loads

Chapter 3 Dead Loads, Soil Loads, and Hydrostatic Pressure

Chapter 4 Live Loads

Chapter 5 Flood Loads

Chapter 6 Reserved for Future Provisions

Chapter 7 Snow Loads

Chapter 8 Rain Loads

Chapter 9 Reserved for Future Provisions

Chapter 10 Ice Loads - Atmospheric Icing

Chapter 11 Seismic Design Criteria

Chapter 12 Seismic Design Requirements for Building Structures

Chapter 13 Seismic Design Requirements for Nonstructural Components

Chapter 14 Material Specific Seismic Design and Detailing Requirements

Chapter 15 Seismic Design Requirements for Nonbuilding Structures

Chapter 16 Seismic Response History Procedures

Chapter 17 Seismic Design Requirements for Seismically Isolated Structures

Chapter 18 Seismic Design Requirements for Structures with Damping Systems

Chapter 19 Soil-Structure Interaction for Seismic Design

Chapter 20 Site Classification Procedure for Seismic Design

Chapter 21 Site-Specific Ground Motion Procedures for Seismic Design

Chapter 22 Seismic Ground Motion Long-Period Transition and Risk Coefficient Maps

Chapter 23 Seismic Design Reference Documents

Chapter 24

Chapter 25

Chapter 26 Wind Loads: General Requirements

Chapter 27 Wind Loads on Buildings‒MWFRS (Directional Procedure)

Chapter 28 Wind Loads on Buildings‒MWFRS (Envelope Procedure)

Chapter 29 Wind Loads on Other Structures and Building Appurtenances‒MWFRS

Chapter 30 Wind Loads ‒ Components and Cladding (C&C)

Chapter 31 Wind Tunnel Procedure

Appendix 11A Quality Assurance Provisions

Appendix 11B Existing Building Provisions

Appendix C Serviceability Considerations

Appendix D Buildings Exempted from Torisional Wind Load Cases

   FIXED LADDER: A ladder that is permanently attached to a structure, building, or equipment.
   GRAB BAR SYSTEM: A bar and associated anchorages and attachments to the structural system, for the support of body weight in locations such as toilets, showers, and tub enclosures.
   GUARDRAIL: A system of components, including anchorages and attachments to the structural system, near open sides of an elevated surface for the purpose of minimizing the possibility of a fall from the elevated surface by people, equipment, or material.
   HANDRAIL SYSTEM: A rail grasped by hand for guidance and support and associated anchorages and attachments to the structural system.
   HELIPAD: A structural surface that is used for landing, taking off, taxiing, and parking of helicopters.
   LIVE LOAD: A load produced by the use and occupancy of the building or other structure that does not include construction or environmental loads, such as wind load, snow load, rain load, earthquake load, flood load, or dead load.
   ROOF LIVE LOAD: A load on a roof produced (1) during maintenance by workers, equipment, and materials and (2) during the life of the structure by movable objects, such as planters or other similar small decorative appurtenances that are not occupancy related.
   SCREEN ENCLOSURE: A building or part thereof, in whole or in part self-supporting, having walls and a roof of insect or sun screening using fiberglass, aluminum, plastic, or similar lightweight netting material, which encloses an occupancy or use such as outdoor swimming pools, patios or decks, and horticultural and agricultural production facilities.
   VEHICLE BARRIER SYSTEM: A system of components, including anchorages and attachments to the structural system near open sides or walls of garage floors or ramps, that acts as a restraint for vehicles.
For occupancies or uses not designed in this chapter, the live load shall be determined in accordance with a method approved by the authority having jurisdiction.
The live loads used in the design of buildings and other structures shall be the maximum loads expected by the intended use or occupancy, but shall in no case be less than the minimum uniformly distributed unit loads required by Table 4-1.
Table 4-1 Minimum Uniformly Distributed Live Loads, L0 , and Minimum Concentrated Live Loads
Occupancy or Use Uniform psf (kN/m2) Cone. lb (kN)
Apartments (see Residential)
Access floor systems

Office use


Computer use



50 (2.4)

100 (4.79)
2,000 (8.9)

2,000 (8.9)
Armories and drill rooms 150 (7.18)a
Assembly areas

Fixed seats (fastened to floor)


Lobbies


Movable seats


Platforms (assembly)


Stage floors


Other assembly areas



60 (2.87)a

100 (4.79)a

100 (4.79)a

100 (4.79)a

150 (7.18)a

100 (4.79)a
Balconies and decks 1.5 times the live load for the area served.
Not required to exceed 100 psf (4.79 kN/m2)
Catwalks for maintenance access 40 (1.92) 300 (1.33)
Corridors

First floor


Other floors



100 (4.79)

Same as occupancy served except as indicated
Dining rooms and restaurants 100 (4.79)a
Dwellings (see Residential)
Elevator machine room grating (on area of 2 in. by 2 in. [50 mm by 50 mm]) 300 (1.33)
Finish light floor plate construction (on area of 1 in. by 1 in. [25 mm by 25 mm]) 200 (0.89)
Fire escapes

On single -family dwellings only

100 (4.79)

40 (1.92)
Fixed ladders See Section 4.5
Garages

Passenger vehicles only


Trucks and buses



40 (1.92)a,b,c

c
Handrails, guardrails, and grab bars See Section 4.5
Helipads 60 (2.87)d,e
nonreducible
e,f,g
Hospitals

Operating rooms, laboratories


Patient rooms


Corridors above first floor



60 (2.87)

40 (1.92)

80 (3.83)


1,000 ( 4.45)

1,000 (4.45)

1,000 ( 4.45)
Hotels (see Residential)
Libraries

Reading rooms


Stack rooms


Corridors above first floor



60 (2.87)

150 (7.18)a,h

80 (3.83)


1,000 ( 4.45)

1,000 ( 4.45)

1,000 ( 4.45)
Manufacturing

Light


Heavy



125 (6.00)a

250 (11.97)a


2,000 (8.90)

3,000 (13.40)
Office buildings

File and computer rooms shall be designed for heavier loads based on anticipated occupancy


Lobbies and first-floor corridors


Offices


Corridors above first floor







100 (4.79)

50 (2.40)

80 (3.83)






2,000 (8.90)

2,000 (8.90)

2,000 (8.90)
Penal institutions

Cell blocks


Corridors



40 (1.92)

100 (4.79)
Recreational uses

Bowling alleys, poolrooms, and similar uses


Dance halls and ballrooms


Gymnasiums


Reviewing stands, grandstands, and bleachers


Stadiums and arenas with fixed seats (fastened to the floor)



75 (3.59)a


100 (4.79)a

100 (4.79)a

100 (4.79)a,k


60 (2.87)a,k
Residential

One- and two-family dwellings


Uninhabitable attics without storage


Uninhabitable attics with storage


Habitable attics and sleeping areas


All other areas except stairs


All other residential occupancies


Private rooms and corridors serving them


Public roomsa and corridors serving them





10 (0.48)l

20 (0.96)m

30 (1.44)

40 (1.92)



40 (1.92)


100 (4.79)
Roofs

Ordinary flat, pitched, and curved roofs


Roofs used for roof gardens


Roofs used for other occupancies



Roofs used for other special purposes



Awnings and canopies


Fabric construction supported by a skeleton structure




Screen enclosure support frame








All other construction


Primary roof members, exposed to a work floor


Single panel point of lower chord of roof trusses or any point along primary structural members supporting roofs over manufacturing, storage warehouses, and repair garages


All other primary roof members


All roof surfaces subject to maintenance workers



20 (0.96)n

100 (4.79)

Same as occupancy served

o




5 (0.24) nonreducible


5 (0.24) nonreducible and based on the tributary area of the roof supported by the frame members

20(0.96)










o








200 (0.89)













2,000 (8.9)






300 (1.33)

300 (1.33)
Schools

Classrooms


Corridors above first floor


First-floor corridors



40 (1.92)

80 (3.83)

100 (4.79)


1,000 (4.45)

1,000 (4.45)

1,000 ( 4.45)
Scuttles, skylight ribs, and accessible ceilings 200 (0.89)
Sidewalks, vehicular driveways, and yards subject to trucking 250 ( 11.97)a,p 8,000 (35.6)q
Stairs and exit ways

One- and two-family dwellings only

100 (4.79)

40 (1.92)
300r

300r
Storage areas above ceilings 20 (0.96)
Storage warehouses (shall be designed for heavier loads if required for anticipated storage)

Light

Heavy




125 (6.00)a

250 ( 11.97)a
Stores

Retail


First floor


Upper floors


Wholesale, all floors





100 (4.79)

75 (3.59)

125 (6.00)a




1,000 ( 4.45)

1,000 (4.45)

1,000 ( 4.45)
Vehicle barriers
See Section 4.5
Walkways and elevated platforms (other than exit ways) 60 (2.87)
Yards and terraces, pedestrian 100 (4.79)a


aLive load reduction for this use is not permitted by Section 4.7 unless specific exceptions apply.
bFloors in garages or portions of a building used for the storage of motor vehicles shall be designed for the uniformly distributed live loads of Table 4-1 or the following concentrated load: (1) for garages restricted to passenger vehicles accommodating not more than nine passengers, 3,000 lb (13.35 kN) acting on an area of 4.5 in. by 4.5 in. (114 mm by 114 mm); and (2) for mechanical parking structures without slab or deck that are used for storing passenger vehicles only, 2,250 lb (10 kN) per wheel.
cDesign for trucks and buses shall be in accordance with AASHTO LRFD Bridge Design Specifications; however, provisions for fatigue and dynamic load allowance therein are not required to be applied.
dUniform load shall be 40 psf (1.92 kN/m2) where the design basis helicopter has a maximum take-off weight of 3,000 lbs (13.35 kN) or less. This load shall not be reduced.
eLabeling of helicopter capacity shall be as required by the authority having jurisdiction .
fTwo single concentrated loads, 8 ft (2.44 m) apart shall be applied on the landing area (representing the helicopter's two main landing gear, whether skid type or wheeled type), each having a magnitude of 0.75 times the maximum take-off weight of the helicopter and located to produce the maximum load effect on the structural elements under consideration. The concentrated loads shall be applied over an area of 8 in. by 8 in. (200 mm by 200 mm) and are not required to act concurrently with other uniform or concentrated live loads.
gA single concentrated load of 3,000 lbs ( 13.35 kN) shall be applied over an area of 4.5 in. by 4.5 in. (114 mm by 114 mm), located so as to produce the maximum load effects on the structural elements under consideration. The concentrated load is not required to act concurrently with other uniform or concentrated live loads.
hThe loading applies to stack room floors that support nonmobile, double-faced library book stacks subject to the following limitations: (1) The nominal book stack unit height shall not exceed 90 in. (2,290 mm); (2) the nominal shelf depth shall not exceed 12 in. (305 mm) for each face; and (3) parallel rows of double-faced book stacks shall be separated by aisles not less than 36 in. (914 mm) wide.
kIn addition to the vertical live loads, the design shall include horizontal swaying forces applied to each row of the seats as follows: 24 lb per linear ft of seat applied in a direction parallel to each row of seats and 10 lb per linear ft of seat applied in a direction perpendicular to each row of seats. The parallel and perpendicular horizontal swaying forces need not be applied simultaneously.
lUninhabitable attic areas without storage are those where the maximum clear height between the joist and rafter is less than 42 in. (1,067 mm), or where there are not two or more adjacent trusses with web configurations capable of accommodating an assumed rectangle 42 in. (1,067 mm) in height by 24 in. (610 mm) in width, or greater, within the plane of the trusses. This live load need not be assumed to act concurrently with any other live load requirement.
mUninhabitable attic areas with storage are those where the maximum clear height between the joist and rafter is 42 in. (1,067 mm) or greater, or where there are two or more adjacent trusses with web configurations capable of accommodating an assumed rectangle 42 in. (1,067 mm) in height by 24 in. (610 mm) in width, or greater, within the plane of the trusses. For attics constructed of trusses, the live load need only be applied to those portions of the bottom chords where both of the following conditions are met:
  1. The attic area is accessible from an opening not less than 20 in. (508 mm) in width by 30 in. (762 mm) in length that is located where the clear height in the attic is a minimum of 30 in. (762 mm) ; and
  2. The slope of the truss bottom chord is no greater than 2 units vertical to 12 units horizontal (9.5% slope).

The remaining portions of the bottom chords shall be designed for a uniformly distributed nonconcurrent live load of not less than 10 lb/ft2 (0.48 kN/m2).

nWhere uniform roof live loads are reduced to less than 20 lb/ft2 (0.96 kN/m2) in accordance with Section 4.8.2 and are applied to the design of structural members arranged so as to create continuity, the reduced roof live load shall be applied to adjacent spans or to alternate spans, whichever produces the greatest unfavorable load effect.
oRoofs used for other special purposes shall be designed for appropriate loads as approved by the authority having jurisdiction.
pOther uniform loads in accordance with an approved method, which contains provisions for truck loadings, shall also be considered where appropriate.
qThe concentrated wheel load shall be applied on an area of 4.5 in. by 4.5 in. (114 mm by 114 mm).
rMinimum concentrated load on stair treads (on area of 2 in. by 2 in. [50 mm by 50 mm]) is to be applied nonconcurrent with the uniform load.
In office buildings or other buildings where partitions will be erected or rearranged, provision for partition weight shall be made, whether or not partitions are shown on the plans. Partition load shall not be less than 15 psf (0.72 kN/m2).
   EXCEPTION: A partition live load is not required where the minimum specified live load exceeds 80 psf (3.83 kN/m2).
The full intensity of the appropriately reduced live load applied only to a position of a structure or member shall be accounted for if it produces a more unfavorable load effect than the same intensity applied over the full structure or member. Roof live loads shall be distributed as specified in Table 4-1.
Floors, roofs, and other similar surfaces shall be designed to support safely the uniformly distributed live loads prescribed in Section 4.3 or the concentrated load, in pounds or kilonewtons(kN), given in Table 4-1, whichever produces the greater load effects. Unless otherwise specified, the indicated concentration shall be assumed to be uniformly distributed over an area 2.5 ft (762 mm) by 2.5 ft (762 mm) and shall be located so as to produce the maximum load effects in the members.
All handrail and guardrail systems shall be designed to resist a single concentrated load of 200 lb (0.89 kN) applied in any direction at any point on the handrail or top rail to produce the maximum load effect on the element being considered and to transfer this load through the supports to the structure.
   Further, all handrail and guardrail systems shall be designed to resist a load of 50 lb/ft (pound-force per linear foot) (0.73 kN/m) applied in any direction along the handrail or top rail. This load need not be assumed to act concurrently with the load specified in the preceding paragraph, and this load need not be considered for the following occupancies:

  
  1. one- and two-family dwellings, and
  2. factory, industrial, and storage occupancies, in areas that are not accessible to the public and that serve an occupant load not greater than 50.


Intermediate rails (all those except the handrail or top rail) and panel fillers shall be designed to withstand a horizontally applied normal load of 50 lb (0.22 kN) on an area not to exceed 12 in. by 12 in. (305 mm by 305 mm) including openings and space between rails and located so as to produce the maximum load effects. Reactions due to this loading are not required to be superimposed with the loads specified in either preceding paragraph.
Grab bar systems shall be designed to resist a single concentrated load of 250 lb (1.11 kN) applied in any direction at any point on the grab bar to produce the maximum load effect.
Vehicle barrier systems for passenger vehicles shall be designed to resist a single load of 6,000 lb (26.70 kN) applied horizontally in any direction to the barrier system, and shall have anchorages or attachments capable of transferring this load to the structure. For design of the system, the load shall be assumed to act at heights between 1 ft 6 in. (460 mm) and 2 ft 3 in. (686 mm) above the floor or ramp surface, located to produce the maximum load effects. The load shall be applied on an area not to exceed l2 in. by 12 in. (305 mm by 305 mm). This load is not required to act concurrently with any handrail or guardrail system loadings specified in Section 4.5.1. Vehicle barrier systems in garages accommodating trucks and buses shall be designed in accordance with AASHTO LRFD Bridge Design Specifications.
The minimum design live load on fixed ladders with rungs shall be a single concentrated load of 300 lb (1.33 kN), and shall be applied at any point to produce the maximum load effect on the element being considered. The number and position of additional concentrated live load units shall be a minimum of 1 unit of 300 lb (1.33 kN) for every 10 ft (3.05 m) of ladder height.
    Where rails of fixed ladders extend above a floor or platform at the top of the ladder, each side rail extension shall be designed to resist a single concentrated live load of 100 lb (0.445 kN) in any direction at any height up to the top of the side rail extension. Ships ladders with treads instead of rungs shall have minimum design loads as stairs, defined in Table 4-1.
The live loads specified in Sections 4.3 through 4.5 shall be assumed to include adequate allowance for ordinary impact conditions. Provision shall be made in the structural design for uses and loads that involve unusual vibration and impact forces.
All elements subject to dynamic loads from elevators shall be designed for impact loads and deflection limits prescribed by ASME A17.1.
For the purpose of design, the weight of machinery and moving loads shall be increased as follows to allow for impact: (1) light machinery, shaft- or motor-driven, 20 Percent; and (2) reciprocating machinery or power-driven units, 50 percent. All percentages shall be increased where specified by the manufacturer.
Except for roof uniform live loads, all other minimum uniformly distributed live loads, Lo in Table 4-1, shall be permitted to be reduced in accordance with the requirements of Sections 4.7.2 through 4.7.6.
Subject to the limitations of Sections 4.7.3 through 4.7.6, members for which a value of KLLAT is 400 ft2 (37.16 m2) or more are permitted to be designed for a reduced live load in accordance with the following formula :
(4.7-1)
In SI:
where
L = reduced design live load per ft2 (m2) of area supported by the member
L0 = unreduced design live load per ft2 (m2) of area supported by the member (see Table 4-1)
KLL = live load element factor (see Table 4-2)
AT = tributary area in ft2 (m2)

L shall not be less than 0.50L0 for members supporting one floor and L shall not be less than 0.40L0 for members supporting two or more floors.

Table 4-2 Live Load Element Factor, KLL
Element KLLa
Interior columns 4
Exterior columns without cantilever slabs 4
Edge columns with cantilever slabs 3
Corner columns with cantilever slabs 2
Edge beams without cantilever slabs 2
Interior beams 2
All other members not identified, including:
    Edge beams with cantilever slabs
    Cantilever beams
    One-way slabs
    Two-way slabs
    Members without provisions for continuous shear transfer normal to their span
1
aIn lieu of the preceding values, KLL is permitted to be calculated.
Live loads that exceed 100 lb/ft2 (4.79 kN/m2) shall not be reduced.

   EXCEPTION: Live loads for members supporting two or more floors shall be permitted to be reduced by 20 percent.
The live loads shall not be reduced in passenger vehicle garages.

   EXCEPTION: Live loads for members supporting two or more floors shall be permitted to be reduced by 20 percent.
Live loads shall not be reduced in assembly uses.
The tributary area, AT, for one-way slabs shall not exceed an area defined by the slab span times a width normal to the span of 1.5 times the slab span.
The minimum uniformly distributed roof live loads, Lo in Table 4-1, are permitted to be reduced in accordance with the requirements of Sections 4.8.2 and 4.8.3.
Ordinary flat, pitched, and curved roofs, and awning and canopies other than those of fabric construction supported by a skeleton structure, are permitted to be designed for a reduced roof live load, as specified in Eq. 4.8-1 or other controlling combinations of loads, as specified in Chapter 2, whichever produces the greater load effect. In structures such as greenhouses, where special scaffolding is used as a work surface for workers and materials during maintenance and repair operations, a lower roof load than specified in Eq. 4.8-1 shall not be used unless approved by the authority having jurisdiction. On such structures, the minimum roof live load shall be 12 psf (0.58 kN/m2).
(4.8-1)
In SI:
where
Lr = reduced roof live load per ft2 (m2) of horizontal projection supported by the member
Lo = unreduced design roof live load per ft2 (m2) of horizontal projection supported by the member (see Table 4-1)

The reduction factors R1 and R2 shall be determined as follows:
in SI:

where
AT = tributary area in ft2 (m2) supported by the member and


where, for a pitched roof,
F = number of inches of rise per foot(in SI: F = 0.12 x slope, with slope expressed in percentage points)
and, for an arch or dome,
F = rise-to-span ratio multipliedby 32.
Roofs that have an occupancy function, such as roof gardens, assembly purposes, or other special purposes are permitted to have their uniformly distributed live load reduced in accordance with the requirements of Section 4.7.
The crane live load shall be the rated capacity of the crane. Design loads for the runway beams, including connections and support brackets, of moving bridge cranes and monorail cranes shall include the maximum wheel loads of the crane and the vertical impact, lateral, and longitudinal forces induced by the moving crane.
The maximum wheel loads shall be the wheel loads produced by the weight of the bridge, as applicable, plus the sum of the rated capacity and the weight of the trolley with the trolley positioned on its runway at the location where the resulting load effect is maximized.
The maximum wheel loads of the crane shall be increased by the percentages shown in the following text to determine the induced vertical impact or vibration force:

Monorail cranes (powered) 25
Cab-operated or remotely operated bridge cranes(powered) 25
Pendant-operated bridge cranes (powered) 10
Bridge cranes or monorail cranes with hand-geared bridge, trolley, and hoist 0
The lateral force on crane runway beams with electrically powered trolleys shall be calculated as 20 percent of the sum of the rated capacity of the crane and the weight of the hoist and trolley. The lateral force shall be assumed to act horizontally at the traction surface of a runway beam, in either direction perpendicular to the beam, and shall be distributed with due regard to the lateral stiffness of the runway beam and supporting structure.
The longitudinal force on crane runway beams, except for bridge cranes with hand-geared bridges, shall be calculated as 10 percent of the maximum wheel loads of the crane. The longitudinal force shall be assumed to act horizontally at the traction surface of a runway beam in either direction parallel to the beam.
This section lists the consensus standards and other documents that are adopted by reference within this chapter:

AASHTO
American Association of State Highway and Transportation Officials
444 North Capitol Street, NW, Suite 249 Washington, DC 20001

Section 4.5.3, Table 4-1
AASHTO LRFD Bridge Design Specifications, ons 4th edition, 2007, with 2008 interim revisions

ASME
American Society of Mechanical Engineers
Three Park Avenue
New York, NY 10016-5900

ASME A17.1
Section 4.6.2
American National Standard Safety Code for Elevators and Escalators, 2007.
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