The following words and terms shall, for the purposes of this chapter, have the meanings shown herein.
ALLOWABLE STRESS DESIGN. A method of proportioning structural members, such that elastically computed stresses produced in the members by nominal loads do not exceed specified allowable stresses (also called "working stress design").
DEAD LOADS. The weight of materials of construction incorporated into the building, including but not limited to walls, floors, roofs, ceilings, stairways, builtin partitions, finishes, cladding and other similarly incorporated architectural and structural items, and the weight of fixed service equipment, such as cranes, plumbing stacks and risers, electrical feeders, heating, ventilating and airconditioning systems and automatic sprinkler systems.
DESIGN STRENGTH. The product of the nominal strength and a resistance factor (or strength reduction factor).
DIAPHRAGM. A horizontal or sloped system acting to transmit lateral forces to the verticalresisting elements. When the term "diaphragm" is used, it shall include horizontal bracing systems.
Diaphragm, blocked. In lightframe construction, a diaphragm in which all sheathing edges not occurring on a framing member are supported on and fastened to blocking.
Diaphragm boundary. In lightframe construction, a location where shear is transferred into or out of the diaphragm sheathing. Transfer is either to a boundary element or to another forceresisting element.
Diaphragm chord. A diaphragm boundary element perpendicular to the applied load that is assumed to take axial stresses due to the diaphragm moment.
Diaphragm flexible. A diaphragm is flexible for the purpose of distribution of story shear and torsional moment where so indicated in Section 12.3.1 of ASCE 7, as modified in Section 1613.6.1.
Diaphragm, rigid. A diaphragm is rigid for the purpose of distribution of story shear and torsional moment when the lateral deformation of the diaphragm is less than or equal to two times the average story drift.
DURATION OF LOAD. The period of continuous application of a given load, or the aggregate of periods of intermittent applications of the same load.
ESSENTIAL FACILITIES. Buildings and other structures that are intended to remain operational in the event of extreme environmental loading from flood, wind, snow or earthquakes.
FABRIC PARTITION. A partition consisting of a finished surface made of fabric, without a continuous rigid backing, that is directly attached to a framing system in which the vertical framing members are spaced greater than 4 feet (1219 mm) on center.
FACTORED LOAD. The product of a nominal load and a load factor.
GUARD. See Section 1002.1.
IMPACT LOAD. The load resulting from moving machinery, elevators, craneways, vehicles and other similar forces and kinetic loads, pressure and possible surcharge from fixed or moving loads.
LIMIT STATE. A condition beyond which a structure or member becomes unfit for service and is judged to be no longer useful for its intended function (serviceability limit state) or to be unsafe (strength limit state).
LIVE LOADS. Those loads produced by the use and occupancy of the building or other structure and do not include construction or environmental loads such as wind load, snow load, rain load, earthquake load, flood load or dead load.
LIVE LOADS (ROOF). Those loads produced (1) during maintenance by workers, equipment and materials; and (2) during the life of the structure by movable objects such as planters and by people.
LOAD AND RESISTANCE FACTOR DESIGN (LRFD). A method of proportioning structural members and their connections using load and resistance factors such that no applicable limit state is reached when the structure is subjected to appropriate load combinations. The term "LRFD" is used in the design of steel and wood structures.
LOAD EFFECTS. Forces and deformations produced in structural members by the applied loads.
LOAD FACTOR. A factor that accounts for deviations of the actual load from the nominal load, for uncertainties in the analysis that transforms the load into a load effect, and for the probability that more than one extreme load will occur simultaneously.
LOADS. Forces or other actions that result from the weight of building materials, occupants and their possessions, environmental effects, differential movement and restrained dimensional changes. Permanent loads are those loads in which variations over time are rare or of small magnitude, such as dead loads. All other loads are variable loads (see also "Nominal loads").
NOMINAL LOADS. The magnitudes of the loads specified in this chapter (dead, live, soil, wind, snow, rain, flood and earthquake).
OCCUPANCY CATEGORY. A category used to determine structural requirements based on occupancy.
OTHER STRUCTURES. Structures, other than buildings, for which loads are specified in this chapter.
PANEL (PART OF A STRUCTURE). The section of a floor, wall or roof comprised between the supporting frame of two adjacent rows of columns and girders or column bands of floor or roof construction.
RESISTANCE FACTOR. A factor that accounts for deviations of the actual strength from the nominal strength and the manner and consequences of failure (also called "strength reduction factor").
STRENGTH, NOMINAL. The capacity of a structure or member to resist the effects of loads, as determined by computations using specified material strengths and dimensions and equations derived from accepted principles of structural mechanics or by field tests or laboratory tests of scaled models, allowing for modeling effects and differences between laboratory and field conditions.
STRENGTH, REQUIRED. Strength of a member, cross section or connection required to resist factored loads or related internal moments and forces in such combinations as stipulated by these provisions.
STRENGTH DESIGN. A method of proportioning structural members such that the computed forces produced in the members by factored loads do not exceed the member design strength [also called "load and resistance factor design" (LRFD)]. The term "strength design" is used in the design of concrete and masonry structural elements.
VEHICLE BARRIER SYSTEM. A system of building components near open sides of a garage floor or ramp or building walls that act as restraints for vehicles.
D = Dead load.
E = Combined effect of horizontal and vertical earthquake induced forces as defined in Section 12.4.2 of ASCE 7.
F = Load due to fluids with welldefined pressures and maximum heights.
F_{a} = Flood load in accordance with Chapter 5 of ASCE 7.
H = Load due to lateral earth pressures, ground water pressure or pressure of bulk materials.
L = Live load, except roof live load, including any permitted live load reduction.
L_{r} = Roof live load including any permitted live load reduction.
R = Rain load.
S = Snow load.
T = Selfstraining force arising from contraction or expansion resulting from temperature change, shrinkage, moisture change, creep in component materials, movement due to differential settlement or combinations thereof.
W = Load due to wind pressure.
 Floor and roof live loads.
 Ground snow load, P_{g}.
 Basic wind speed (3second gust), miles per hour (mph) (km/hr) and wind exposure.
 Seismic design category and site class.
 Flood design data, if located in flood hazard areas established in Section 1612.3.
 Design loadbearing values of soils.
 Flatroof snow load, P_{f}.
 Snow exposure factor, C_{e}.
 Snow load importance factor, I.
 Thermal factor, C_{t}.
 Basic wind speed (3second gust), miles per hour (km/hr).
 Wind importance factor, I, and occupancy category.
 Wind exposure. Where more than one wind exposure is utilized, the wind exposure and applicable wind direction shall be indicated.
 The applicable internal pressure coefficient.
 Components and cladding. The design wind pressures in terms of psf (kN/m^{2}) to be used for the design of exterior component and cladding materials not specifically designed by the registered design professional.
 Seismic importance factor, I, and occupancy category.
 Mapped spectral response accelerations, S_{S} and S_{1}.
 Site class.
 Spectral response coefficients, S_{DS} and S_{D1}.
 Seismic design category.
 Basic seismicforceresisting system(s).
 Design base shear.
 Seismic response coefficient(s), C_{S}.
 Response modification factor(s), R.
 Analysis procedure used.
 In flood hazard areas not subject to highvelocity wave action, the elevation of the proposed lowest floor, including the basement.
 In flood hazard areas not subject to highvelocity wave action, the elevation to which any nonresidential building will be dry floodproofed.
 In flood hazard areas subject to highvelocity wave action, the proposed elevation of the bottom of the lowest horizontal structural member of the lowest floor, including the basement.
Buildings and other structures, and parts thereof, shall be designed and constructed to support safely the factored loads in load combinations defined in this code without exceeding the appropriate strength limit states for the materials of construction. Alternatively, buildings and other structures, and parts thereof, shall be designed and constructed to support safely the nominal loads in load combinations defined in this code without exceeding the appropriate specified allowable stresses for the materials of construction.
Loads and forces for occupancies or uses not covered in this chapter shall be subject to the approval of the building official.
The deflections of structural members shall not exceed the more restrictive of the limitations of Sections 1604.3.2 through 1604.3.5 or that permitted by Table 1604.3.
TABLE 1604.3
DEFLECTION LIMITS^{a, b, c, h, i}
CONSTRUCTION  L  S or W ^{f}  D + L^{d, g} 
Roof members:^{e } Supporting plaster ceiling 



Floor members  l/360  —  l/240 
Exterior walls and interior partitions: 



Farm buildings  —  —  l/180 
Greenhouses  —  —  l/120 
For SI: 1 foot = 304.8 mm.
 For structural roofing and siding made of formed metal sheets, the total load deflection shall not exceed l/60. For secondary roof structural members supporting formed metal roofing, the live load deflection shall not exceed l/150. For secondary wall members supporting formed metal siding, the design wind load deflection shall not exceed l/90. For roofs, this exception only applies when the metal sheets have no roof covering.
 Interior partitions not exceeding 6 feet in height and flexible, folding and portable partitions are not governed by the provisions of this section. The deflection criterion for interior partitions is based on the horizontal load defined in Section 1607.13.
 See Section 2403 for glass supports.
 For wood structural members having a moisture content of less than 16 percent at time of installation and used under dry conditions, the deflection resulting from L + 0.5D is permitted to be substituted for the deflection resulting from L + D.
 The above deflections do not ensure against ponding. Roofs that do not have sufficient slope or camber to assure adequate drainage shall be investigated for ponding. See Section 1611 for rain and ponding requirements and Section 1503.4 for roof drainage requirements.
 The wind load is permitted to be taken as 0.7 times the "component and cladding" loads for the purpose of determining deflection limits herein.
 For steel structural members, the dead load shall be taken as zero.
 For aluminum structural members or aluminum panels used in skylights and sloped glazing framing, roofs or walls of sunroom additions or patio covers, not supporting edge of glass or aluminum sandwich panels, the total load deflection shall not exceed l/60. For continuous aluminum structural members supporting edge of glass, the total load deflection shall not exceed l/175 for each glass lite or l/60 for the entire length of the member, whichever is more stringent. For aluminum sandwich panels used in roofs or walls of sunroom additions or patio covers, the total load deflection shall not exceed l/120.
 For cantilever members, l shall be taken as twice the length of the cantilever.
Load effects on structural members and their connections shall be determined by methods of structural analysis that take into account equilibrium, general stability, geometric compatibility and both short and longterm material properties.
Members that tend to accumulate residual deformations under repeated service loads shall have included in their analysis the added eccentricities expected to occur during their service life.
Any system or method of construction to be used shall be based on a rational analysis in accordance with wellestablished principles of mechanics. Such analysis shall result in a system that provides a complete load path capable of transferring loads from their point of origin to the loadresisting elements.
The total lateral force shall be distributed to the various vertical elements of the lateralforceresisting system in proportion to their rigidities, considering the rigidity of the horizontal bracing system or diaphragm. Rigid elements assumed not to be a part of the lateralforceresisting system are permitted to be incorporated into buildings provided their effect on the action of the system is considered and provided for in the design. Except where diaphragms are flexible, or are permitted to be analyzed as flexible, provisions shall be made for the increased forces induced on resisting elements of the structural system resulting from torsion due to eccentricity between the center of application of the lateral forces and the center of rigidity of the lateralforceresisting system.
Every structure shall be designed to resist the overturning effects caused by the lateral forces specified in this chapter. See Section 1609 for wind loads, Section 1610 for lateral soil loads and Section 1613 for earthquake loads.
Each building and structure shall be assigned an occupancy category in accordance with Table 1604.5.
TABLE 1604.5
OCCUPANCY CATEGORY OF BUILDINGS AND OTHER STRUCTURES
OCCUPANCY  NATURE OF OCCUPANCY  
I  Buildings and other structures that represent a low hazard to human life in the event of failure, including but not limited to:  
II  Buildings and other structures except those listed in Occupancy Categories I, III and IV  
III  Buildings and other structures that represent a substantial hazard to human life in the event of failure, including but not limited to: • Buildings and other structures whose primary occupancy is public assembly with an occupant load greater than 300. • Buildings and other structures containing elementary school, secondary school or day care facilities with an occupant load greater than 250. • Buildings and other structures containing adult education facilities, such as colleges and universities, with an occupant load greater than 500. • Group I2 occupancies with an occupant load of 50 or more resident patients but not having surgery or emergency treatment facilities. • Group I3 occupancies. • Any other occupancy with an occupant load greater than 5,000^{a}. • Powergenerating stations, water treatment facilities for potable water, waste water treatment facilities and other public utility facilities not included in Occupancy Category IV. • Buildings and other structures not included in Occupancy Category IV containing sufficient quantities of toxic or explosive substances to be dangerous to the public if released.  
IV  Buildings and other structures designated as essential facilities, including but not limited to: • Group I2 occupancies having surgery or emergency treatment facilities. • Fire, rescue, ambulance and police stations and emergency vehicle garages. • Designated earthquake, hurricane or other emergency shelters. • Designated emergency preparedness, communications and operations centers and other facilities required for emergency response. • Powergenerating stations and other public utility facilities required as emergency backup facilities for Occupancy Category IV structures. • Structures containing highly toxic materials as defined by Section 307 where the quantity of the material exceeds the maximum allowable quantities of Table 307.1(2). • Aviation control towers, air traffic control centers and emergency aircraft hangars. • Buildings and other structures having critical national defense functions. • Water storage facilities and pump structures required to maintain water pressure for fire suppression. 
a. For purposes of occupant load calculation, occupancies required by Table 1004.1.1 to use gross floor area calculations shall be permitted to use net floor areas to determine the total occupant load.
 The reactions resulting from the dead load and live load specified in Table 1607.1, or the snow load specified in Section 1608, in accordance with Section 1605, acting on all portions of the deck.
 The reactions resulting from the dead load and live load specified in Table 1607.1, or the snow load specified in Section 1608, in accordance with Section 1605, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck.
 The load combinations specified in Section 1605.2, 1605.3.1 or 1605.3.2,
 The load combinations specified in Chapters 18 through 23, and
 The load combinations with overstrength factor specified in Section 12.4.3.2 of ASCE 7 where required by Section 12.2.5.2, 12.3.3.3 or 12.10.2.1 of ASCE 7. With the simplified procedure of ASCE 7 Section 12.14, the load combinations with overstrength factor of Section 12.14.3.2 of ASCE 7 shall be used.
Where the load combinations with overstrength factor in Section 12.4.3.2 of ASCE 7 apply, they shall be used as follows:
 The basic combinations for strength design with overstrength factor in lieu of Equations 165 and 167 in Section 1605.2.1.
 The basic combinations for allowable stress design with overstrength factor in lieu of Equations 1612, 1613 and 1615 in Section 1605.3.1.
 The basic combinations for allowable stress design with overstrength factor in lieu of Equations 1620 and 1621 in Section 1605.3.2.
Where strength design or load and resistance factor design is used, structures and portions thereof shall resist the most critical effects from the following combinations of factored loads:
1.4(D + F) (Equation 161)
1.2(D + F + T) + 1.6(L + H) + 0.5(L_{r} or S or R) (Equation 162)
1.2D + 1.6(L_{r} or S or R) + (f_{1}L or 0.8W) (Equation 163)
1.2D + 1.6W + f_{1}L + 0.5(L_{r} or S or R) (Equation 164)
1.2D + 1.0E + f_{1}L + f_{2}S (Equation 165)
0.9D + 1.6W + 1.6H (Equation 166)
0.9D + 1.0E + 1.6H (Equation 167)
where:
f_{1} = 1 for floors in places of public assembly, for live loads in excess of 100 pounds per square foot (4.79 kN/m^{2}), and for parking garage live load, and
= 0.5 for other live loads.
f_{2} = 0.7 for roof configurations (such as saw tooth) that do not shed snow off the structure, and
= 0.2 for other roof configurations.
Exception: Where other factored load combinations are specifically required by the provisions of this code, such combinations shall take precedence.
Where allowable stress design (working stress design), as permitted by this code, is used, structures and portions thereof shall resist the most critical effects resulting from the following combinations of loads:
D + F (Equation 168)
D + H + F + L + T (Equation 169)
D + H + F + (L_{r} or S or R) (Equation 1610)
D + H + F + 0.75(L + T) + 0.75(L_{r} or S or R) (Equation 1611)
D + H + F + (W or 0.7E) (Equation 1612)
D + H + F + 0.75(W or 0.7E) + 0.75L + 0.75(L_{r} or S or R) (Equation 1613)
0.6D + W + H (Equation 1614)
0.6D + 0.7E + H (Equation 1615)
 Crane hook loads need not be combined with roof live load or with more than threefourths of the snow load or onehalf of the wind load.
 Flat roof snow loads of 30 psf (1.44 kN/m^{2}) or less and roof live loads of 30 psf or less need not be combined with seismic loads. Where flat roof snow loads exceed 30 psf (1.44 kN/m^{2}), 20 percent shall be combined with seismic loads.
In lieu of the basic load combinations specified in Section 1605.3.1, structures and portions thereof shall be permitted to be designed for the most critical effects resulting from the following combinations. When using these alternative basic load combinations that include wind or seismic loads, allowable stresses are permitted to be increased or load combinations reduced where permitted by the material chapter of this code or the referenced standards. For load combinations that include the counteracting effects of dead and wind loads, only twothirds of the minimum dead load likely to be in place during a design wind event shall be used. Where wind loads are calculated in accordance with Chapter 6 of ASCE 7, the coefficient w in the following equations shall be taken as 1.3. For other wind loads, w shall be taken as 1. When using these alternative load combinations to evaluate sliding, overturning and soil bearing at the soilstructure interface, the reduction of foundation overturning from Section 12.13.4 in ASCE 7 shall not be used. When using these alternative basic load combinations for proportioning foundations for loadings, which include seismic loads, the vertical seismic load effect, E_{v}, in Equation 12.44 of ASCE 7 is permitted to be taken equal to zero.
D + L + (L_{r} or S or R) (Equation 1616)
D + L + (wW) (Equation 1617)
D + L + wW + S/2 (Equation 1618)
D + L + S + wW/2 (Equation 1619)
D + L + S + E/1.4 (Equation 1620)
0.9D + E/1.4 (Equation 1621)
 Crane hook loads need not be combined with roof live loads or with more than threefourths of the snow load or onehalf of the wind load.
 Flat roof snow loads of 30 psf (1.44 kN/m^{2}) or less and roof live loads of 30 psf or less need not be combined with seismic loads. Where flat roof snow loads exceed 30 psf (1.44 kN/m^{2}), 20 percent shall be combined with seismic loads.
 Dead load, D, plus the gross weight of the helicopter, D_{h}, plus snow load, S.
 Dead load, D, plus two single concentrated impact loads, L, approximately 8 feet (2438 mm) apart applied anywhere on the touchdown pad (representing each of the helicopter's two main landing gear, whether skid type or wheeled type), having a magnitude of 0.75 times the gross weight of the helicopter. Both loads acting together total 1.5 times the gross weight of the helicopter.
 Dead load, D, plus a uniform live load, L, of 100 psf (4.79 kN/m^{2}).
Live loads are those loads defined in Section 1602.1.
TABLE 1607.1
MINIMUM UNIFORMLY DISTRIBUTED LIVE LOADS, L_{o}, AND MINIMUM CONCENTRATED LIVE LOADS^{g}
OCCUPANCY OR USE  UNIFORM  CONCENTRATED 
1. Apartments (see residential)  —  — 
2. Access floor systems 


3. Armories and drill rooms  150  — 
4. Assembly areas and theaters  60  — 
5.Balconies (exterior) and decks^{h}  Same as occupancy served  — 
6. Bowling alleys  75  — 
7. Catwalks  40  300 
8. Cornices  60  — 
9. Corridors, except as otherwise indicated  100  — 
10. Dance halls and ballrooms  100  — 
11. Dining rooms and restaurants  100  — 
12. Dwellings (see residential)  —  — 
13. Elevator machine room grating  —  300 
14. Finish light floor plate construction  —  200 
15. Fire escapes
 100 40  — 
16. Garages (passenger vehicles only)  40 Note a  
17. Grandstands  —  — 
18. Gymnasiums, main floors and balconies  100  — 
See Section 1607.7  
20. Hospitals 


21. Hotels (see residential)  —  — 
22. Libraries 


continued
TABLE 1607.1—continued
MINIMUM UNIFORMLY DISTRIBUTED LIVE LOADS, L_{o}, AND MINIMUM CONCENTRATED LIVE LOADS^{g}
OCCUPANCY OR USE  UNIFORM  CONCENTRATED 
23. Manufacturing 


24. Marquees  75  — 
25. Office buildings 


 —  
27. Residential 
 — 
28. Reviewing stands, grandstands and  Note c  
29. Roofs 


30. Schools 


31. Scuttles, skylight ribs and accessible  —  200 
32. Sidewalks, vehicular driveways and  250^{d}  8,000^{e} 
33. Skating rinks  100  — 
continued
TABLE 1607.1—continued
MINIMUM UNIFORMLY DISTRIBUTED LIVE LOADS, L_{o}, AND MINIMUM CONCENTRATED LIVE LOADS^{g}
OCCUPANCY OR USE  UNIFORM  CONCENTRATED 
34. Stadiums and arenas 
 — 
35. Stairs and exits 
 Note f 
36. Storage warehouses 
 
37. Stores 


38.  See Section 1607.7.3  
39. Walkways and elevated platforms  60  — 
100  — 
For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm^{2},
1 square foot = 0.0929 m^{2},
1 pound per square foot = 0.0479 kN/m^{2}, 1 pound = 0.004448 kN,
1 pound per cubic foot = 16 kg/m^{3}
a. Floors in garages or portions of buildings used for the storage of motor vehicles shall be designed for the uniformly distributed live loads of Table 1607.1 or the following concentrated loads: (1) for garages restricted to passenger vehicles accommodating not more than nine passengers, 3,000 pounds acting on an area of 4.5 inches by 4.5 inches; (2) for mechanical parking structures without slab or deck which are used for storing passenger vehicles only, 2,250 pounds per wheel.
b. The loading applies to stack room floors that support nonmobile, doublefaced library bookstacks, subject to the following limitations:
1. The nominal bookstack unit height shall not exceed 90 inches;
2. The nominal shelf depth shall not exceed 12 inches for each face; and
3. Parallel rows of doublefaced bookstacks shall be separated by aisles not less than 36 inches wide.
c. Design in accordance with the ICC 300.
d. Other uniform loads in accordance with an approved method which contains provisions for truck loadings shall also be considered where appropriate.
e. The concentrated wheel load shall be applied on an area of 4.5 inches by 4.5 inches.
f. Minimum concentrated load on stair treads (on area of 4 square inches) is 300 pounds.
g. Where snow loads occur that are in excess of the design conditions, the structure shall be designed to support the loads due to the increased loads caused by drift buildup or a greater snow design determined by the building official (see Section 1608). For specialpurpose roofs, see Section 1607.11.2.2.
h. See Section 1604.8.3 for decks attached to exterior walls.
i. Attics without storage are those where the maximum clear height between the joist and rafter is less than 42 inches, or where there are not two or more adjacent trusses with the same web configuration capable of containing a rectangle 42 inches high by 2 feet wide, or greater, located within the plane of the truss. For attics without storage, this live load need not be assumed to act concurrently with any other live load requirements.
j. For attics with limited storage and constructed with trusses, this live load need only be applied to those portions of the bottom chord where there are two or more adjacent trusses with the same web configuration capable of containing a rectangle 42 inches high by 2 feet wide or greater, located within the plane of the truss. The rectangle shall fit between the top of the bottom chord and the bottom of any other truss member, provided that each of the following criteria is met:
i. The attic area is accessible by a pulldown stairway or framed opening in accordance with Section 1209.2, and
ii. The truss shall have a bottom chord pitch less than 2:12.
iii. Bottom chords of trusses shall be designed for the greater of actual imposed dead load or 10 psf, uniformly distributed over the entire span.
k. Attic spaces served by a fixed stair shall be designed to support the minimum live load specified for habitable attics and sleeping rooms.
l. Roofs used for other special purposes shall be designed for appropriate loads as approved by the building official.
Minimum live loads for garages having trucks or buses shall be as specified in Table 1607.6, but shall not be less than 50 psf (2.40 kN/m^{2}), unless other loads are specifically justified and approved by the building official. Actual loads shall be used where they are greater than the loads specified in the table.
TABLE 1607.6
UNIFORM AND CONCENTRATED LOADS
LOADING  UNIFORM LOAD  CONCENTRATED LOAD  
For moment design  For shear design  
H2044 and HS2044  640  18,000  26,000 
H1544 and HS1544  480  13,500  19,500 
For SI: 1 pound per linear foot = 0.01459 kN/m, 1 pound = 0.004448 kN,
1 ton = 8.90 kN.
 An H loading class designates a twoaxle truck with a semitrailer. An HS loading class designates a tractor truck with a semitrailer. The numbers following the letter classification indicate the gross weight in tons of the standard truck and the year the loadings were instituted.
 See Section 1607.6.1 for the loading of multiple spans.
 For one and twofamily dwellings, only the single concentrated load required by Section 1607.7.1.1 shall be applied.
 In Group I3, F, H and S occupancies, for areas that are not accessible to the general public and that have an occupant load less than 50, the minimum load shall be 20 pounds per foot (0.29 kN/m).
Subject to the limitations of Sections 1607.9.1.1 through 1607.9.1.4, members for which a value of K_{LL}A_{T} is 400 square feet (37.16 m^{2}) or more are permitted to be designed for a reduced live load in accordance with the following equation:
(Equation 1622)
where:
L = Reduced design live load per square foot (meter) of area supported by the member.
L_{o} = Unreduced design live load per square foot (meter) of area supported by the member (see Table 1607.1).
K_{LL} = Live load element factor (see Table 1607.9.1).
A_{T} = Tributary area, in square feet (square meters).
L shall not be less than 0.50L_{o} for members supporting one floor and L shall not be less than 0.40L_{o} for members supporting two or more floors.
TABLE 1607.9.1
LIVE LOAD ELEMENT FACTOR, K_{LL}
ELEMENT  K_{LL} 
Interior columns  4 
Edge columns with cantilever slabs  3 
Corner columns with cantilever slabs  2 
All other members not identified above including:  1 
 The live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent, but the live load shall not be less than L as calculated in Section 1607.9.1.
 For uses other than storage, where approved, additional live load reductions shall be permitted where shown by the registered design professional that a rational approach has been used and that such reductions are warranted.
As an alternative to Section 1607.9.1, floor live loads are permitted to be reduced in accordance with the following provisions. Such reductions shall apply to slab systems, beams, girders, columns, piers, walls and foundations.
 A reduction shall not be permitted in Group A occupancies.
 A reduction shall not be permitted where the live load exceeds 100 psf (4.79 kN/m^{2}) except that the design live load for members supporting two or more floors is permitted to be reduced by 20 percent.
Exception: For uses other than storage, where approved, additional live load reductions shall be permitted where shown by the registered design professional that a rational approach has been used and that such reductions are warranted.
3. A reduction shall not be permitted in passenger vehicle parking garages except that the live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent.
4. For live loads not exceeding 100 psf (4.79 kN/m^{2}), the design live load for any structural member supporting 150 square feet (13.94 m^{2}) or more is permitted to be reduced in accordance with Equation 1623.
5. For oneway slabs, the area, A, for use in Equation 1623 shall not exceed the product of the slab span and a width normal to the span of 0.5 times the slab span.
R = 0.08(A  150) (Equation 1623)
For SI: R = 0.861(A  13.94)
Such reduction shall not exceed the smallest of:
 40 percent for horizontal members;
 60 percent for vertical members; or
 R as determined by the following equation.
R = 23.1(1 + D/L_{o}) (Equation 1624)
where:
A = Area of floor supported by the member, square feet (m^{2}).
D = Dead load per square foot (m^{2}) of area supported.
L_{o} = Unreduced live load per square foot (m^{2}) of area supported.
R = Reduction in percent.
Ordinary flat, pitched and curved roofs, and awnings and canopies other than of fabric construction supported by lightweight rigid skeleton structures, are permitted to be designed for a reduced roof live load as specified in the following equations or other controlling combinations of loads in Section 1605, whichever produces the greater load. 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 the following equations shall not be used unless approved by the building official. Such structures shall be designed for a minimum roof live load of 12 psf (0.58 kN/m^{2}).
L_{r} = L_{o} R_{1}R_{2} (Equation 1625)
where: 12 ≤ L_{r} ≤ 20
For SI: L_{r} = L_{o}R_{1}R_{2}
where: 0.58 ≤ L_{r} ≤ 0.96
L_{r} = Reduced live load per square foot (m^{2}) of horizontal projection in pounds per square foot (kN/m^{2}).
The reduction factors R_{1} and R_{2} shall be determined as follows:
R_{1} = 1 for A_{t} ≤ 200 square feet (18.58 m^{2}) (Equation 1626)
R_{1} = 1.2 — 0.001A_{t} for 200 square feet < A_{t} < 600 square feet (Equation 1627)
For SI: 1.2 — 0.011A_{t} for 18.58 square meters < A_{t} < 55.74 square meters
R_{1} = 0.6 for A_{t} ≥ 600 square feet (55.74 m^{2}) (Equation 1628)
where:
A_{t} = Tributary area (span length multiplied by effective width) in square feet (m^{2}) supported by any structural member, and
R_{2} = 1 for F ≤ 4 (Equation 1629)
R_{2} = 1.2 — 0.05 F for 4 < F < 12 (Equation 1630)
R_{2} = 0.6 for F ≥ 12 (Equation 1631)
where:
F = For a sloped roof, the number of inches of rise per foot (for SI: F = 0.12 × slope, with slope expressed as a percentage), or for an arch or dome, the risetospan ratio multiplied by 32.
The maximum wheel loads of the crane shall be increased by the percentages shown below to determine the induced vertical impact or vibration force:
Monorail cranes (powered) 25 percent
Caboperated or remotely operated bridge cranes (powered) 25 percent
Pendantoperated bridge cranes (powered) 10 percent
Bridge cranes or monorail cranes with handgeared bridge, trolley and hoist 0 percent
 A horizontal distributed load of 5 psf (0.24 kN/m^{2}) applied to the partition framing. The total area used to determine the distributed load shall be the area of the fabric face between the framing members to which the fabric is attached. The total distributed load shall be uniformly applied to such framing members in proportion to the length of each member.
 A concentrated load of 40 pounds (0.176 kN) applied to an 8inch diameter (203 mm) area [50.3 square inches (32 452 mm^{2})] of the fabric face at a height of 54 inches (1372 mm) above the floor.
The ground snow loads to be used in determining the design snow loads for roofs shall be determined in accordance with ASCE 7 or Figure 1608.2 for the contiguous United States and Table 1608.2 for Alaska. Sitespecific case studies shall be made in areas designated "CS" in Figure 1608.2. Ground snow loads for sites at elevations above the limits indicated in Figure 1608.2 and for all sites within the CS areas shall be approved. Ground snow load determination for such sites shall be based on an extreme value statistical analysis of data available in the vicinity of the site using a value with a 2percent annual probability of being exceeded (50year mean recurrence interval). Snow loads are zero for Hawaii, except in mountainous regions as approved by the building official.
TABLE 1608.2
GROUND SNOW LOADS, p_{g} , FOR ALASKAN LOCATIONS
LOCATION  POUNDS PER  LOCATION  POUNDS PER  LOCATION  POUNDS PER 
Adak  30  Galena  60  Petersburg  150 
Anchorage  50  Gulkana  70  St. Paul Islands  40 
Angoon  70  Homer  40  Seward  50 
Barrow  25  Juneau  60  Shemya  25 
Barter Island  35  Kenai  70  Sitka  50 
Bethel  40  Kodiak  30  Talkeetna  120 
Big Delta  50  Kotzebue  60  Unalakleet  50 
Cold Bay  25  McGrath  70  Valdez  160 
Cordova  100  Nenana  80  Whittier  300 
Fairbanks  60  Nome  70  Wrangell  60 
Fort Yukon  60  Palmer  50  Yakutat  150 
For SI: 1 pound per square foot = 0.0479 kN/m^{2}.
FIGURE 1608.2 GROUND SNOW LOADS, pg, FOR THE UNITED STATES (psf)
FIGURE 1608.2—continued GROUND SNOW LOADS, pg, FOR THE UNITED STATES (psf)
 Subject to the limitations of Section 1609.1.1.1, the provisions of ICC 600 shall be permitted for applicable Group R2 and R3 buildings.
 Subject to the limitations of Section 1609.1.1.1, residential structures using the provisions of the AF&PA WFCM.
 Subject to the limitations of Section 1609.1.1.1, residential structures using the provisions of AISI S230.
 Designs using NAAMM FP 1001.
 Designs using TIA222 for antennasupporting structures and antennas.
 Wind tunnel tests in accordance with Section 6.6 of ASCE 7, subject to the limitations in Section 1609.1.1.2.
 The hill, ridge or escarpment is 60 feet (18 288 mm) or higher if located in Exposure B or 30 feet (9144 mm) or higher if located in Exposure C;
 The maximum average slope of the hill exceeds 10 percent; and
 The hill, ridge or escarpment is unobstructed upwind by other such topographic features for a distance from the high point of 50 times the height of the hill or 1 mile (1.61 km), whichever is greater.
 Glazed openings located within 30 feet (9144 mm) of grade shall meet the requirements of the large missile test of ASTM E 1996.
 Glazed openings located more than 30 feet (9144 mm) above grade shall meet the provisions of the small missile test of ASTM E 1996.
TABLE 1609.1.2
WINDBORNE DEBRIS PROTECTION FASTENING
SCHEDULE FOR WOOD STRUCTURAL PANELS^{a, b, c, d}
FASTENER  FASTENER SPACING (inches)  
Panel Span  4 feet <Panel Span ≤6 feet  6 feet <Panel Span ≤8 feet  
No. 8 woodscrewbased anchor with 2inch embedment length  16  10  8 
No. 10 woodscrewbased anchor with 2inch embedment length  16  12  9 
^{1}/_{4}inch diameter lagscrewbased anchor with 2inch embedment length  16  16  16 
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 4.448 N,
1 mile per hour = 0.447 m/s.
 This table is based on 140 mph wind speeds and a 45foot mean roof height.
 Fasteners shall be installed at opposing ends of the wood structural panel. Fasteners shall be located a minimum of 1 inch from the edge of the panel.
 Anchors shall penetrate through the exterior wall covering with an embedment length of 2 inches minimum into the building frame. Fasteners shall be located a minimum of 2^{1}/_{2} inches from the edge of concrete block or concrete.
 Where panels are attached to masonry or masonry/stucco, they shall be attached using vibrationresistant anchors having a minimum ultimate withdrawal capacity of 1,500 pounds.
 Wood structural panels with a minimum thickness of ^{7}/_{16} inch (11.1 mm) and maximum panel span of 8 feet (2438 mm) shall be permitted for opening protection in one and twostory buildings classified as Group R3 or R4 occupancy. Panels shall be precut so that they shall be attached to the framing surrounding the opening containing the product with the glazed opening. Panels shall be predrilled as required for the anchorage method and shall be secured with the attachment hardware provided. Attachments shall be designed to resist the components and cladding loads determined in accordance with the provisions of ASCE 7, with corrosionresistant attachment hardware provided and anchors permanently installed on the building. Attachment in accordance with Table 1609.1.2 with corrosionresistant attachment hardware provided and anchors permanently installed on the building is permitted for buildings with a mean roof height of 45 feet (13 716 mm) or less where wind speeds do not exceed 140 mph (63 m/s).
 Glazing in Occupancy Category I buildings as defined in Section 1604.5, including greenhouses that are occupied for growing plants on a production or research basis, without public access shall be permitted to be unprotected.
 Glazing in Occupancy Category II, III or IV buildings located over 60 feet (18 288 mm) above the ground and over 30 feet (9144 mm) above aggregate surface roofs located within 1,500 feet (458 m) of the building shall be permitted to be unprotected.
The following words and terms shall, for the purposes of Section 1609, have the meanings shown herein.
HURRICANEPRONE REGIONS. Areas vulnerable to hurricanes defined as:
 The U. S. Atlantic Ocean and Gulf of Mexico coasts where the basic wind speed is greater than 90 mph (40 m/s) and
 Hawaii, Puerto Rico, Guam, Virgin Islands and American Samoa.
WINDBORNE DEBRIS REGION. Portions of hurricaneprone regions that are within 1 mile (1.61 km) of the coastal mean high water line where the basic wind speed is 110 mph (48 m/s) or greater; or portions of hurricaneprone regions where the basic wind speed is 120 mph (53 m/s) or greater; or Hawaii.
The basic wind speed, in mph, for the determination of the wind loads shall be determined by Figure 1609. Basic wind speed for the special wind regions indicated, near mountainous terrain and near gorges shall be in accordance with local jurisdiction requirements. Basic wind speeds determined by the local jurisdiction shall be in accordance with Section 6.5.4 of ASCE 7.
In nonhurricaneprone regions, when the basic wind speed is estimated from regional climatic data, the basic wind speed shall be not less than the wind speed associated with an annual probability of 0.02 (50year mean recurrence interval), and the estimate shall be adjusted for equivalence to a 3second gust wind speed at 33 feet (10 m) above ground in Exposure Category C. The data analysis shall be performed in accordance with Section 6.5.4.2 of ASCE 7.
When required, the 3second gust basic wind speeds of Figure 1609 shall be converted to fastestmile wind speeds, V_{fm}, using Table 1609.3.1 or Equation 1632.
(Equation 1632)
where:
V_{3}_{S} = 3second gust basic wind speed from Figure 1609.
TABLE 1609.3.1
EQUIVALENT BASIC WIND SPEEDS^{a, b, c}
V_{3}_{S}  85  90  100  105  110  120  125  130  140  145  150  160  170 
V_{fm}  71  76  85  90  95  104  109  114  123  128  133  142  152 
For SI: 1 mile per hour = 0.44 m/s.
 Linear interpolation is permitted.
 V_{3}_{S} is the 3second gust wind speed (mph).
 V_{fm} is the fastest mile wind speed (mph).
FIGURE 1609 BASIC WIND SPEED (3SECOND GUST)
FIGURE 1609—continued BASIC WIND SPEED (3SECOND GUST)
FIGURE 1609—continued BASIC WIND SPEED (3SECOND GUST) WESTERN GULF OF MEXICO HURRICANE COASTLINE
FIGURE 1609—continued BASIC WIND SPEED (3SECOND GUST) EASTERN GULF OF MEXICO AND SOUTHEASTERN U.S. HURRICANE COASTLINE
FIGURE 1609—continued BASIC WIND SPEED (3SECOND GUST) MID AND NORTHERN ATLANTIC HURRICANE COASTLINE
A ground surface roughness within each 45degree (0.79 rad) sector shall be determined for a distance upwind of the site as defined in Section 1609.4.3 from the categories defined below, for the purpose of assigning an exposure category as defined in Section 1609.4.3.
Surface Roughness B. Urban and suburban areas, wooded areas or other terrain with numerous closely spaced obstructions having the size of singlefamily dwellings or larger.
Surface Roughness C. Open terrain with scattered obstructions having heights generally less than 30 feet (9144 mm). This category includes flat open country, grasslands, and all water surfaces in hurricaneprone regions.
Surface Roughness D. Flat, unobstructed areas and water surfaces outside hurricaneprone regions. This category includes smooth mud flats, salt flats and unbroken ice.
An exposure category shall be determined in accordance with the following:
Exposure B. Exposure B shall apply where the ground surface roughness condition, as defined by Surface Roughness B, prevails in the upwind direction for a distance of at least 2,600 feet (792 m) or 20 times the height of the building, whichever is greater.
Exception: For buildings whose mean roof height is less than or equal to 30 feet (9144 mm), the upwind distance is permitted to be reduced to 1,500 feet (457 m).
Exposure C. Exposure C shall apply for all cases where Exposures B or D do not apply.
Exposure D. Exposure D shall apply where the ground surface roughness, as defined by Surface Roughness D, prevails in the upwind direction for a distance of at least 5,000 feet (1524 m) or 20 times the height of the building, whichever is greater. Exposure D shall extend inland from the shoreline for a distance of 600 feet (183 m) or 20 times the height of the building, whichever is greater.
Roof coverings shall comply with Section 1609.5.1.
Exception: Rigid tile roof coverings that are air permeable and installed over a roof deck complying with Section 1609.5.1 are permitted to be designed in accordance with Section 1609.5.3.
Asphalt shingles installed over a roof deck complying with Section 1609.5.1 shall comply with the windresistance requirements of Section 1507.2.7.1.
Wind loads on rigid tile roof coverings shall be determined in accordance with the following equation:
(Equation 1633)
where:
b = Exposed width, feet (mm) of the roof tile.
C_{L} = Lift coefficient. The lift coefficient for concrete and clay tile shall be 0.2 or shall be determined by test in accordance with Section 1716.2.
GC_{p} = Roof pressure coefficient for each applicable roof zone determined from Chapter 6 of ASCE 7. Roof coefficients shall not be adjusted for internal pressure.
L = Length, feet (mm) of the roof tile.
L_{a} = Moment arm, feet (mm) from the axis of rotation to the point of uplift on the roof tile. The point of uplift shall be taken at 0.76L from the head of the tile and the middle of the exposed width. For roof tiles with nails or screws (with or without a tail clip), the axis of rotation shall be taken as the head of the tile for direct deck application or as the top edge of the batten for battened applications. For roof tiles fastened only by a nail or screw along the side of the tile, the axis of rotation shall be determined by testing. For roof tiles installed with battens and fastened only by a clip near the tail of the tile, the moment arm shall be determined about the top edge of the batten with consideration given for the point of rotation of the tiles based on straight bond or broken bond and the tile profile.
M_{a} = Aerodynamic uplift moment, feetpounds (Nmm) acting to raise the tail of the tile.
q_{h} = Wind velocity pressure, psf (kN/m^{2}) determined from Section 6.5.10 of ASCE 7.
Concrete and clay roof tiles complying with the following limitations shall be designed to withstand the aerodynamic uplift moment as determined by this section.
 The roof tiles shall be either loose laid on battens, mechanically fastened, mortar set or adhesive set.
 The roof tiles shall be installed on solid sheathing which has been designed as components and cladding.
 An underlayment shall be installed in accordance with Chapter 15.
 The tile shall be single lapped interlocking with a minimum head lap of not less than 2 inches (51 mm).
 The length of the tile shall be between 1.0 and 1.75 feet (305 mm and 533 mm).
 The exposed width of the tile shall be between 0.67 and 1.25 feet (204 mm and 381 mm).
 The maximum thickness of the tail of the tile shall not exceed 1.3 inches (33 mm).
 Roof tiles using mortar set or adhesive set systems shall have at least twothirds of the tile's area free of mortar or adhesive contact.
As an alternative to ASCE 7 Section 6.5, the following provisions are permitted to be used to determine the wind effects on regularly shaped buildings, or other structures that are regularly shaped, which meet all of the following conditions:
 The building or other structure is less than or equal to 75 feet (22 860 mm) in height with a heighttoleast width ratio of 4 or less, or the building or other structure has a fundamental frequency greater than or equal to 1 hertz.
 The building or other structure is not sensitive to dynamic effects.
 The building or other structure is not located on a site for which channeling effects or buffeting in the wake of upwind obstructions warrant special consideration.
 The building shall meet the requirements of a simple diaphragm building as defined in ASCE 7 Section 6.2, where wind loads are only transmitted to the main windforceresisting system (MWFRS) at the diaphragms.
 For open buildings, multispan gable roofs, stepped roofs, sawtooth roofs, domed roofs, roofs with slopes greater than 45 degrees (0.79 rad), solid freestanding walls and solid signs, and rooftop equipment, apply ASCE 7 provisions.
Coefficients and variables used in the alternative allheights method equations are as follows:
C_{net} = Netpressure coefficient based on K_{d} [(G) (C_{p}) – (GC_{pi})], in accordance with Table 1609.6.2(2).
G = Gust effect factor for rigid structures in accordance with ASCE 7 Section 6.5.8.1.
K_{d} = Wind directionality factor in accordance with ASCE 7 Table 64.
P_{net} = Design wind pressure to be used in determination of wind loads on buildings or other structures or their components and cladding, in psf (kN/m^{2}).
q_{s} = Wind stagnation pressure in psf (kN/m^{2}) in accordance with Table 1609.6.2(1).
TABLE 1609.6.2(1)
WIND VELOCITY PRESSURE (q_{s}) AT STANDARD HEIGHT OF 33 FEET^{a}
BASIC WIND SPEED (mph) 
85 
90 
100 
105 
110 
120 
125 
130 
140 
150 
160 
170 
PRESSURE, q_{s} (psf) 
18.5 
20.7 
25.6 
28.2 
31.0 
36.9 
40.0 
43.3 
50.2 
57.6 
65.5 
74.0 
For SI: 1 foot = 304.8 mm, 1 mph = 0.44 m/s, 1 psf = 47.88 Pa.
a. For basic wind speeds not shown, use q_{s} = 0.00256 V^{2}.
TABLE 1609.6.2(2)
NET PRESSURE COEFFICIENTS, C_{net}^{a, b}
STRUCTURE OR 
DESCRIPTION 
C_{net} FACTOR 

1. Main wind 
Enclosed 
Partially enclosed 

+ Internal 
 Internal 
+ Internal 
 Internal 

Windward wall 
0.43 
0.73 
0.11 
1.05 

Leeward wall 
0.51 
0.21 
0.83 
0.11 

Sidewall 
0.66 
0.35 
0.97 
0.04 

Windward 
1.28 
1.28 

Leeward 
0.85 
0.85 

Roofs: 
Enclosed 
Partially enclosed 

Wind perpendicular to ridge 
+ Internal 
 Internal 
+ Internal 
 Internal 

Leeward roof or flat roof 
0.66 
0.35 
0.97 
0.04 

Windward roof slopes: 

Slope = 2:12 (10°) 
Condition 1 
1.09 
0.79 
1.41 
0.47 

Condition 2 
0.28 
0.02 
0.60 
0.34 

Slope = 4:12 (18°) 
Condition 1 
0.73 
0.42 
1.04 
0.11 

Condition 2 
0.05 
0.25 
0.37 
0.57 

Slope = 5:12 (23°) 
Condition 1 
0.58 
0.28 
0.90 
0.04 

Condition 2 
0.03 
0.34 
0.29 
0.65 

Slope = 6:12 (27°) 
Condition 1 
0.47 
0.16 
0.78 
0.15 

Condition 2 
0.06 
0.37 
0.25 
0.68 

Slope = 7:12 (30°) 
Condition 1 
0.37 
0.06 
0.68 
0.25 

Condition 2 
0.07 
0.37 
0.25 
0.69 

Slope = 9:12 (37°) 
Condition 1 
0.27 
0.04 
0.58 
0.35 

Condition 2 
0.14 
0.44 
0.18 
0.76 

Slope = 12:12 (45°) 
0.14 
0.44 
0.18 
0.76 

Wind parallel to ridge and flat roofs 
1.09 
0.79 
1.41 
0.47 

Nonbuilding Structures: Chimneys, Tanks and Similar Structures: 

h/D 

1 
7 
25 

Square (Wind normal to face) 
0.99 
1.07 
1.53 

Square (Wind on diagonal) 
0.77 
0.84 
1.15 

Hexagonal or Octagonal 
0.81 
0.97 
1.13 

Round 
0.65 
0.81 
0.97 

Open signs and lattice frameworks 
Ratio of solid to gross area 

< 0.1 
0.1 to 0.29 
0.3 to 0.7 

Flat 
1.45 
1.30 
1.16 

Round 
0.87 
0.94 
1.08 
(continued)
TABLE 1609.6.2(2)—continued
NET PRESSURE COEFFICIENTS, C_{net}^{a, b}
STRUCTURE OR 
DESCRIPTION 
C_{net} FACTOR 

2. Components and cladding not in areas of discontinuity—roofs and overhangs 
Roof elements and slopes 
Enclosed 
Partially enclosed 

Gable of hipped configurations (Zone 1) 

Positive 
10 square feet or less 
0.58 
0.89 

100 square feet or more 
0.41 
0.72 

Negative 
10 square feet or less 
1.00 
1.32 

100 square feet or more 
0.92 
1.23 

Overhang: Flat < Slope < 6:12 (27°) See ASCE 7 Figure 611B Zone 1 

Negative 
10 square feet or less 
1.45 

100 square feet or more 
1.36 

500 square feet or more 
0.94 

6:12 (27°) < Slope < 12:12 (45°) See ASCE 7 Figure 611D Zone 1 

Positive 
10 square feet or less 
0.92 
1.23 

100 square feet or more 
0.83 
1.15 

Negative 
10 square feet or less 
1.00 
1.32 

100 square feet or more 
0.83 
1.15 

Monosloped configurations (Zone 1) 
Enclosed 
Partially enclosed 

Positive 
10 square feet or less 
0.49 
0.81 

100 square feet or more 
0.41 
0.72 

Negative 
10 square feet or less 
1.26 
1.57 

100 square feet or more 
1.09 
1.40 

Tall flattopped roofs h > 60' 
Enclosed 
Partially enclosed 

Flat < Slope < 2:12 (10°) (Zone 1) See ASCE 7 Figure 617 Zone 1 

Negative 
10 square feet or less 
1.34 
1.66 

500 square feet or more 
0.92 
1.23 
(continued)
TABLE 1609.6.2(2)—continued
NET PRESSURE COEFFICIENTS, C_{net}^{a, b}
STRUCTURE OR 
DESCRIPTION 
C_{net} FACTOR 

3. Components and cladding in areas of discontinuities—roofs and overhangs 
Roof elements and slopes 
Enclosed 
Partially enclosed 

Gable or hipped configurations at ridges, eaves and rakes (Zone 2) 

Positive 
10 square feet or less 
0.58 
0.89 

100 square feet or more 
0.41 
0.72 

Negative 
10 square feet or less 
1.68 
2.00 

100 square feet or more 
1.17 
1.49 

Overhang for Slope Flat < Slope < 6:12 (27°) See ASCE 7 Figure 611C Zone 2 

Negative 
10 square feet or less 
1.87 

100 square feet or more 
1.87 

6:12 (27°) < Slope < 12:12 (45°) Figure 611D 
Enclosed 
Partially enclosed 

Positive 
10 square feet or less 
0.92 
1.23 

100 square feet or more 
0.83 
1.15 

Negative 
10 square feet or less 
1.17 
1.49 

100 square feet or more 
1.00 
1.32 

Overhang for 6:12 (27°) < Slope < 12:12 (45°) See ASCE 7 Figure 611D Zone 2 

Negative 
10 square feet or less 
1.70 

500 square feet or more 
1.53 

Monosloped configurations at ridges, eaves and rakes (Zone 2) 

Positive 
10 square feet or less 
0.49 
0.81 

100 square feet or more 
0.41 
0.72 

Negative 
10 square feet or less 
1.51 
1.83 

100 square feet or more 
1.43 
1.74 

Tall flat topped roofs h > 60' 
Enclosed 
Partially enclosed 

Flat < Slope < 2:12 (10°) (Zone 2) See ASCE 7 Figure 617 Zone 2 

Negative 
10 square feet or less 
2.11 
2.42 

500 square feet or more 
1.51 
1.83 

Gable or hipped configurations at corners (Zone 3) See ASCE 7 Figure 611C Zone 3 

Flat < Slope < 6:12 (27°) 
Enclosed 
Partially enclosed 

Positive 
10 square feet or less 
0.58 
0.89 

100 square feet or more 
0.41 
0.72 

Negative 
10 square feet or less 
2.53 
2.85 

100 square feet or more 
1.85 
2.17 
(continued)
TABLE 1609.6.2(2)—continued
NET PRESSURE COEFFICIENTS, C_{net}^{a, b}
STRUCTURE OR 
DESCRIPTION 
C_{net} FACTOR 

3. Components and cladding in areas of discontinuity—roofs and overhangs 
Overhang for Slope Flat < Slope < 6:12 (27°) See ASCE 7 Figure 611C Zone 3 

Negative 
10 square feet or less 
3.15 

100 square feet or more 
2.13 

6:12 (27°) < 12:12 (45°) See ASCE 7 Figure 611D Zone 3 

Positive 
10 square feet or less 
0.92 
1.23 

100 square feet or more 
0.83 
1.15 

Negative 
10 square feet or less 
1.17 
1.49 

100 square feet or more 
1.00 
1.32 

Overhang for 6:12 (27°) < Slope < 12:12 (45°) 
Enclosed 
Partially enclosed 

Negative 
10 square feet or less 
1.70 

100 square feet or more 
1.53 

Monosloped Configurations at corners (Zone 3) See ASCE 7 Figure 614B Zone 3 

Flat < Slope < 7:12 (30°) 

Positive 
10 square feet or less 
0.49 
0.81 

100 square feet or more 
0.41 
0.72 

Negative 
10 square feet or less 
2.62 
2.93 

100 square feet or more 
1.85 
2.17 

Tall flat topped roofs h > 60' 
Enclosed 
Partially enclosed 

Flat < Slope < 2:12 (10°) (Zone 3) See ASCE 7 Figure 617 Zone 3 

Negative 
10 square feet or less 
2.87 
3.19 

500 square feet or more 
2.11 
2.42 

4. Components and cladding not in areas of discontinuity—walls and parapets 
Enclosed 
Partially enclosed 

Positive 
10 square feetor less 
1.00 
1.32 

500 square feet or more 
0.75 
1.06 

Negative 
10 square feet or less 
1.09 
1.40 

500 square feet or more 
0.83 
1.15 

Wall Elements: h > 60' (Zone 4) See ASCE 7 Figure 617 Zone 4 

Positive 
20 square feet or less 
0.92 
1.23 

500 square feet or more 
0.66 
0.98 

Negative 
20 square feet or less 
0.92 
1.23 

500 square feet or more 
0.75 
1.06 

Positive 
2.87 
3.19 

Negative 
1.68 
2.00 
TABLE 1609.6.2(2)—continued
NET PRESSURE COEFFICIENTS, C_{net}^{a, b}
STRUCTURE OR 
DESCRIPTION 
C_{net} FACTOR 

5. Components and cladding in areas of discontinuity— walls and parapets 
Enclosed 
Partially enclosed 

Positive 
10 square feet or less 
1.00 
1.32 

500 square feet or more 
0.75 
1.06 

Negative 
10 square feet or less 
1.34 
1.66 

500 square feet or more 
0.83 
1.15 

Wall elements: h > 60' (Zone 5) See ASCE 7 Figure 617 Zone 4 

Positive 
20 square feet or less 
0.92 
1.23 

500 square feet or more 
0.66 
0.98 

Negative 
20 square feet or less 
1.68 
2.00 

500 square feet or more 
1.00 
1.32 

Positive 
3.64 
3.95 

Negative 
2.45 
2.76 
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m^{2}, 1 degree = 0.0175 rad.
a. Linear interpolation between values in the table is permitted.
b. Some C_{net} values have been grouped together. Less conservative results may be obtained by applying ASCE 7 provisions.
When using the alternative allheights method, the MWFRS, and components and cladding of every structure shall be designed to resist the effects of wind pressures on the building envelope in accordance with Equation 1634.
P_{net} = q_{s} K_{z} C_{net} [IK_{zt}] (Equation 1634)
Design wind forces for the MWFRS shall not be less than 10 psf (0.48 kN/m^{2}) multiplied by the area of the structure projected on a plane normal to the assumed wind direction (see ASCE 7 Section 6.1.4 for criteria). Design net wind pressure for components and cladding shall not be less than 10 psf (0.48 kN/m^{2}) acting in either direction normal to the surface.
_{z} and K_{zt}. Velocity pressure exposure coefficient, K_{z}, shall be determined in accordance with ASCE 7 Section 6.5.6.6 and the topographic factor, K_{zt}, shall be determined in accordance with ASCE 7 Section 6.5.7.
 For the windward side of a structure, K_{zt} and K_{z} shall be based on height z.
 For leeward and sidewalls, and for windward and leeward roofs, K_{zt} and K_{z} shall be based on mean roof height h.
_{net}. For the design of the MWFRS and for components and cladding, the sum of the internal and external net pressure shall be based on the net pressure coefficient, C_{net}.
 The pressure coefficient, C_{net}, for walls and roofs shall be determined from Table 1609.6.2(2).
 Where C_{net} has more than one value, the more severe wind load condition shall be used for design.
Wind pressure for each component or cladding element is applied as follows using C_{net} values based on the effective wind area, A, contained within the zones in areas of discontinuity of width and/or length "a," "2a" or "4a" at: corners of roofs and walls; edge strips for ridges, rakes and eaves; or field areas on walls or roofs as indicated in figures in tables in ASCE 7 as referenced in Table 1609.6.2(2) in accordance with the following:
 Calculated pressures at local discontinuities acting over specific edge strips or corner boundary areas.
 Include "field" (Zone 1, 2 or 4, as applicable) pressures applied to areas beyond the boundaries of the areas of discontinuity.
 Where applicable, the calculated pressures at discontinuities (Zones 2 or 3) shall be combined with design pressures that apply specifically on rakes or eave overhangs.
DESCRIPTION OF BACKFILL MATERIAL^{c}  UNIFIED SOIL  DESIGN LATERAL SOIL LOAD^{a}  
Active pressure  Atrest pressure  
Wellgraded, clean gravels; gravelsand mixes  GW  30  60 
Poorly graded clean gravels; gravelsand mixes  GP  30  60 
Silty gravels, poorly graded gravelsand mixes  GM  40  60 
Clayey gravels, poorly graded gravelandclay mixes  GC  45  60 
Wellgraded, clean sands; gravelly sand mixes  SW  30  60 
Poorly graded clean sands; sandgravel mixes  SP  30  60 
Silty sands, poorly graded sandsilt mixes  SM  45  60 
Sandsilt clay mix with plastic fines  SMSC  45  100 
Clayey sands, poorly graded sandclay mixes  SC  60  100 
Inorganic silts and clayey silts  ML  45  100 
Mixture of inorganic silt and clay  MLCL  60  100 
Inorganic clays of low to medium plasticity  CL  60  100 
Organic silts and silt clays, low plasticity  OL  Note b  Note b 
Inorganic clayey silts, elastic silts  MH  Note b  Note b 
Inorganic clays of high plasticity  CH  Note b  Note b 
OH  Note b  Note b 
For SI: 1 pound per square foot per foot of depth = 0.157 kPa/m, 1 foot = 304.8 mm.
 Design lateral soil loads are given for moist conditions for the specified soils at their optimum densities. Actual field conditions shall govern. Submerged or saturated soil pressures shall include the weight of the buoyant soil plus the hydrostatic loads.
 Unsuitable as backfill material.
 The definition and classification of soil materials shall be in accordance with ASTM D 2487.
Each portion of a roof shall be designed to sustain the load of rainwater that will accumulate on it if the primary drainage system for that portion is blocked plus the uniform load caused by water that rises above the inlet of the secondary drainage system at its design flow. The design rainfall shall be based on the 100year hourly rainfall rate indicated in Figure 1611.1 or on other rainfall rates determined from approved local weather data.
R = 5.2(d_{s} + d_{h}) (Equation 1635)
For SI: R = 0.0098(d_{s} + d_{h})
where:
d_{h} = Additional depth of water on the undeflected roof above the inlet of secondary drainage system at its design flow (i.e., the hydraulic head), in inches (mm).
d_{s} = Depth of water on the undeflected roof up to the inlet of secondary drainage system when the primary drainage system is blocked (i.e., the static head), in inches (mm).
R = Rain load on the undeflected roof, in psf (kN/m^{2}). When the phrase "undeflected roof" is used, deflections from loads (including dead loads) shall not be considered when determining the amount of rain on the roof.
[P] FIGURE 1611.1
100YEAR, 1HOUR RAINFALL (INCHES) EASTERN UNITED STATES
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
[P] FIGURE 1611.1—continued
100YEAR, 1HOUR RAINFALL (INCHES) CENTRAL UNITED STATES
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
[P] FIGURE 1611.1—continued
100YEAR, 1HOUR RAINFALL (INCHES) WESTERN UNITED STATES
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
[P] FIGURE 1611.1—continued
100YEAR, 1HOUR RAINFALL (INCHES) ALASKA
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
[P] FIGURE 1611.1—continued
100YEAR, 1HOUR RAINFALL (INCHES) HAWAII
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
The following words and terms shall, for the purposes of this section, have the meanings shown herein.
BASE FLOOD. The flood having a 1percent chance of being equaled or exceeded in any given year.
BASE FLOOD ELEVATION. The elevation of the base flood, including wave height, relative to the National Geodetic Vertical Datum (NGVD), North American Vertical Datum (NAVD) or other datum specified on the Flood Insurance Rate Map (FIRM).
BASEMENT. The portion of a building having its floor subgrade (below ground level) on all sides.
This definition of "Basement" is limited in application to the provisions of Section 1612 (see "Basement" in Section 502.1).
DESIGN FLOOD. The flood associated with the greater of the following two areas:
 Area with a flood plain subject to a 1percent or greater chance of flooding in any year; or
 Area designated as a flood hazard area on a community's flood hazard map, or otherwise legally designated.
DESIGN FLOOD ELEVATION. The elevation of the "design flood," including wave height, relative to the datum specified on the community's legally designated flood hazard map. In areas designated as Zone AO, the design flood elevation shall be the elevation of the highest existing grade of the building's perimeter plus the depth number (in feet) specified on the flood hazard map. In areas designated as Zone AO where a depth number is not specified on the map, the depth number shall be taken as being equal to 2 feet (610 mm).
DRY FLOODPROOFING. A combination of design modifications that results in a building or structure, including the attendant utility and sanitary facilities, being water tight with walls substantially impermeable to the passage of water and with structural components having the capacity to resist loads as identified in ASCE 7.
EXISTING CONSTRUCTION. Any buildings and structures for which the "start of construction" commenced before the effective date of the community's first flood plain management code, ordinance or standard. "Existing construction" is also referred to as "existing structures."
EXISTING STRUCTURE. See "Existing construction."
FLOOD or FLOODING. A general and temporary condition of partial or complete inundation of normally dry land from:
 The overflow of inland or tidal waters.
 The unusual and rapid accumulation or runoff of surface waters from any source.
FLOOD DAMAGERESISTANT MATERIALS. Any construction material capable of withstanding direct and prolonged contact with floodwaters without sustaining any damage that requires more than cosmetic repair.
FLOOD HAZARD AREA. The greater of the following two areas:
 The area within a flood plain subject to a 1percent or greater chance of flooding in any year.
 The area designated as a flood hazard area on a community's flood hazard map, or otherwise legally designated.
FLOOD HAZARD AREA SUBJECT TO HIGHVELOCITY WAVE ACTION. Area within the flood hazard area that is subject to highvelocity wave action, and shown on a Flood Insurance Rate Map (FIRM) or other flood hazard map as Zone V, VO, VE or V130.
FLOOD INSURANCE RATE MAP (FIRM). An official map of a community on which the Federal Emergency Management Agency (FEMA) has delineated both the special flood hazard areas and the risk premium zones applicable to the community.
FLOOD INSURANCE STUDY. The official report provided by the Federal Emergency Management Agency containing the Flood Insurance Rate Map (FIRM), the Flood Boundary and Floodway Map (FBFM), the water surface elevation of the base flood and supporting technical data.
FLOODWAY. The channel of the river, creek or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height.
LOWEST FLOOR. The floor of the lowest enclosed area, including basement, but excluding any unfinished or floodresistant enclosure, usable solely for vehicle parking, building access or limited storage provided that such enclosure is not built so as to render the structure in violation of this section.
SPECIAL FLOOD HAZARD AREA. The land area subject to flood hazards and shown on a Flood Insurance Rate Map or other flood hazard map as Zone A, AE, A130, A99, AR, AO, AH, V, VO, VE or V130.
START OF CONSTRUCTION. The date of issuance for new construction and substantial improvements to existing structures, provided the actual start of construction, repair, reconstruction, rehabilitation, addition, placement or other improvement is within 180 days after the date of issuance. The actual start of construction means the first placement of permanent construction of a building (including a manufactured home) on a site, such as the pouring of a slab or footings, installation of pilings or construction of columns.
Permanent construction does not include land preparation (such as clearing, excavation, grading or filling), the installation of streets or walkways, excavation for a basement, footings, piers or foundations, the erection of temporary forms or the installation of accessory buildings such as garages or sheds not occupied as dwelling units or not part of the main building. For a substantial improvement, the actual "start of construction" means the first alteration of any wall, ceiling, floor or other structural part of a building, whether or not that alteration affects the external dimensions of the building.
SUBSTANTIAL DAMAGE. Damage of any origin sustained by a structure whereby the cost of restoring the structure to its beforedamaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.
SUBSTANTIAL IMPROVEMENT. Any repair, reconstruction, rehabilitation, addition or improvement of a building or structure, the cost of which equals or exceeds 50 percent of the market value of the structure before the improvement or repair is started. If the structure has sustained substantial damage, any repairs are considered substantial improvement regardless of the actual repair work performed. The term does not, however, include either:
 Any project for improvement of a building required to correct existing health, sanitary or safety code violations identified by the building official and that are the minimum necessary to assure safe living conditions.
 Any alteration of a historic structure provided that the alteration will not preclude the structure's continued designation as a historic structure.
Where design flood elevations are not included in the flood hazard areas established in Section 1612.3, or where floodways are not designated, the building official is authorized to require the applicant to:
 Obtain and reasonably utilize any design flood elevation and floodway data available from a federal, state or other source; or
 Determine the design flood elevation and/or floodway in accordance with accepted hydrologic and hydraulic engineering practices used to define special flood hazard areas. Determinations shall be undertaken by a registered design professional who shall document that the technical methods used reflect currently accepted engineering practice.
The following documentation shall be prepared and sealed by a registered design professional and submitted to the building official:
1. For construction in flood hazard areas not subject to highvelocity wave action:
1.1. The elevation of the lowest floor, including the basement, as required by the lowest floor elevation inspection in Section 110.3.3.
1.2. For fully enclosed areas below the design flood elevation where provisions to allow for the automatic entry and exit of floodwaters do not meet the minimum requirements in Section 2.6.2.1 of ASCE 24, construction documents shall include a statement that the design will provide for equalization of hydrostatic flood forces in accordance with Section 2.6.2.2 of ASCE 24.
1.3. For dry floodproofed nonresidential buildings, construction documents shall include a statement that the dry floodproofing is designed in accordance with ASCE 24.
2. For construction in flood hazard areas subject to highvelocity wave action:
FIGURE 1609—continued
BASIC WIND SPEED (3SECOND GUST)
2.1. The elevation of the bottom of the lowest horizontal structural member as required by the lowest floor elevation inspection in Section 110.3.3.
2.2. Construction documents shall include a statement that the building is designed in accordance with ASCE 24, including that the pile or column foundation and building or structure to be attached thereto is designed to be anchored to resist flotation, collapse and lateral movement due to the effects of wind and flood loads acting simultaneously on all building components, and other load requirements of Chapter 16.
2.3. For breakaway walls designed to resist a nominal load of less than 10 psf (0.48 kN/m^{2}) or more than 20 psf (0.96 kN/m^{2}), construction documents shall include a statement that the breakaway wall is designed in accordance with ASCE 24.
Every structure, and portion thereof, including nonstructural components that are permanently attached to structures and their supports and attachments, shall be designed and constructed to resist the effects of earthquake motions in accordance with ASCE 7, excluding Chapter 14 and Appendix 11A. The seismic design category for a structure is permitted to be determined in accordance with Section 1613 or ASCE 7.
Exceptions:
 Detached one and twofamily dwellings, assigned to Seismic Design Category A, B or C, or located where the mapped shortperiod spectral response acceleration, S_{S}, is less than 0.4 g.
 The seismicforceresisting system of woodframe buildings that conform to the provisions of Section 2308 are not required to be analyzed as specified in this section.
 Agricultural storage structures intended only for incidental human occupancy.
 Structures that require special consideration of their response characteristics and environment that are not addressed by this code or ASCE 7 and for which other regulations provide seismic criteria, such as vehicular bridges, electrical transmission towers, hydraulic structures, buried utility lines and their appurtenances and nuclear reactors.
The following words and terms shall, for the purposes of this section, have the meanings shown herein.
DESIGN EARTHQUAKE GROUND MOTION. The earthquake ground motion that buildings and structures are specifically proportioned to resist in Section 1613.
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION. The most severe earthquake effects considered by this code.
MECHANICAL SYSTEMS. For the purposes of determining seismic loads in ASCE 7, mechanical systems shall include plumbing systems as specified therein.
ORTHOGONAL. To be in two horizontal directions, at 90 degrees (1.57 rad) to each other.
SEISMIC DESIGN CATEGORY. A classification assigned to a structure based on its occupancy category and the severity of the design earthquake ground motion at the site.
SEISMICFORCERESISTING SYSTEM. That part of the structural system that has been considered in the design to provide the required resistance to the prescribed seismic forces.
SITE CLASS. A classification assigned to a site based on the types of soils present and their engineering properties as defined in Section 1613.5.2.
SITE COEFFICIENTS. The values of F_{a} and F_{v} indicated in Tables 1613.5.3(1) and 1613.5.3(2), respectively.
The parameters S_{s} and S_{1} shall be determined from the 0.2 and 1second spectral response accelerations shown on Figures 1613.5(1) through 1613.5(14). Where S_{1} is less than or equal to 0.04 and S_{s} is less than or equal to 0.15, the structure is permitted to be assigned to Seismic Design Category A.
FIGURE 1613.5(1)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR THE CONTERMINOUS UNITED STATES OF
0.2 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(1)—continued
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR THE CONTERMINOUS UNITED STATES OF
0.2 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(2)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR THE CONTERMINOUS UNITED STATES
OF 1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(2)—continued
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR THE CONTERMINOUS UNITED STATES
OF 1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(3)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 1 OF 0.2 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(3)—continued
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 1 OF
0.2 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(4)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 1 OF
1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(4)—continued
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 1 OF
1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(5)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 2 OF
0.2 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(6)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 2 OF
1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(7)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 3 OF
0.2 SEC SPECTRAL RESPONSE ACCELERATION (5% PERCENT OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(8)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 3 OF
1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(9)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR REGION 4 OF
0.2 AND 1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(10)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR HAWAII OF
0.2 AND 1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(11)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR ALASKA OF
0.2 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(12)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR ALASKA OF
1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(13)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR PUERTO RICO, CULEBRA, VIEQUES, ST. THOMAS,
ST. JOHN AND ST. CROIX OF 0.2 AND 1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.5(14)
MAXIMUM CONSIDERED EARTHQUAKE GROUND MOTION FOR GUAM AND TUTUILLA OF
0.2 AND 1.0 SEC SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B
Based on the site soil properties, the site shall be classified as either Site Class A, B, C, D, E or F in accordance with Table 1613.5.2. When the soil properties are not known in sufficient detail to determine the site class, Site Class D shall be used unless the building official or geotechnical data determines that Site Class E or F soil is likely to be present at the site.
TABLE 1613.5.2
SITE CLASS DEFINITIONS
SITE  SOIL PROFILE  AVERAGE PROPERTIES IN TOP 100 feet, SEE SECTION 1613.5.5  
Soil shear wave velocity, , (ft/s)  Standard penetration resistance,  Soil undrained shear strength, , (psf)  
A  Hard rock  > 5,000  N/A  N/A 
B  Rock  2,500 <≤ 5,000  N/A  N/A 
C  Very dense soil and soft rock  1,200 <≤ 2,500  > 50  ≥ 2,000 
D  Stiff soil profile  600 ≤≤ 1,200  15 ≤≤ 50  1,000 ≤≤ 2,000 
E  Soft soil profile  < 600  < 15  < 1,000 
E  —  Any profile with more than 10 feet of soil having the following characteristics: 1. Plasticity index PI > 20, 2. Moisture content w ≥ 40%, and 3. Undrained shear strength < 500 psf  
F  —  Any profile containing soils having one or more of the following characteristics: 1. Soils vulnerable to potential failure or collapse under seismic loading such as liquefiable 2. Peats and/or highly organic clays (H > 10 feet of peat and/or highly organic clay where 3. Very high plasticity clays (H > 25 feet with plasticity index PI > 75) 4. Very thick soft/medium stiff clays (H > 120 feet) 
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m^{2}, 1 pound per square foot = 0.0479 kPa. N/A = Not applicable
The maximum considered earthquake spectral response acceleration for short periods, S_{MS}, and at 1second period, S_{M}_{1}, adjusted for site class effects shall be determined by Equations 1636 and 1637, respectively:
S_{MS} = F_{a}S_{s} (Equation 1636)
S_{M}_{1} = F_{v} S_{1} (Equation 1637)
where:
F_{a} = Site coefficient defined in Table 1613.5.3(1).
F_{v} = Site coefficient defined in Table 1613.5.3(2).
S_{S} = The mapped spectral accelerations for short periods as determined in Section 1613.5.1.
S_{1} = The mapped spectral accelerations for a 1second period as determined in Section 1613.5.1.
TABLE 1613.5.3(1)
VALUES OF SITE COEFFICIENT F_{a} ^{a }
CLASS  MAPPED SPECTRAL RESPONSE ACCELERATION AT SHORT PERIOD  
S_{s} ≤ 0.25  S_{s} = 0.50  S_{s} = 0.75  S_{s} = 1.00  S_{s} ≥ 1.25  
A  0.8  0.8  0.8  0.8  0.8 
B  1.0  1.0  1.0  1.0  1.0 
C  1.2  1.2  1.1  1.0  1.0 
D  1.6  1.4  1.2  1.1  1.0 
E  2.5  1.7  1.2  0.9  0.9 
F  Note b  Note b  Note b  Note b  Note b 
 Use straightline interpolation for intermediate values of mapped spectral response acceleration at short period, S_{s}.
 Values shall be determined in accordance with Section 11.4.7 of ASCE 7.
TABLE 1613.5.3(2)
VALUES OF SITE COEFFICIENT F_{V} ^{a}
CLASS  MAPPED SPECTRAL RESPONSE ACCELERATION AT 1SECOND PERIOD  
S_{1} ≤ 0.1  S_{1} = 0.2  S_{1} = 0.3  S_{1} = 0.4  S_{1} ≥ 0.5  
A  0.8  0.8  0.8  0.8  0.8 
B  1.0  1.0  1.0  1.0  1.0 
C  1.7  1.6  1.5  1.4  1.3 
D  2.4  2.0  1.8  1.6  1.5 
E  3.5  3.2  2.8  2.4  2.4 
F  Note b  Note b  Note b  Note b  Note b 
 Use straightline interpolation for intermediate values of mapped spectral response acceleration at 1second period, S_{1}.
 Values shall be determined in accordance with Section 11.4.7 of ASCE 7.
Fivepercent damped design spectral response acceleration at short periods, S_{DS}, and at 1second period, S_{D}_{1}, shall be determined from Equations 1638 and 1639, respectively:
(Equation 1638)
(Equation 1639)
where:
S_{MS} = The maximum considered earthquake spectral response accelerations for short period as determined in Section 1613.5.3.
S_{M}_{1} = The maximum considered earthquake spectral response accelerations for 1second period as determined in Section 1613.5.3.
Site classification for Site Class C, D or E shall be determined from Table 1613.5.5.
The notations presented below apply to the upper 100 feet (30 480 mm) of the site profile. Profiles containing distinctly different soil and/or rock layers shall be subdivided into those layers designated by a number that ranges from 1 to n at the bottom where there is a total of n distinct layers in the upper 100 feet (30 480 mm). The symbol i then refers to any one of the layers between 1 and n.
where:
v_{si} = The shear wave velocity in feet per second (m/s).
d_{i} = The thickness of any layer between 0 and 100 feet
(30 480 mm).
where:
(Equation 1640)
N_{i} is the Standard Penetration Resistance (ASTM D 1586) not to exceed 100 blows/foot (328 blows/m) as directly measured in the field without corrections. When refusal is met for a rock layer, N_{i} shall be taken as 100 blows/foot (328 blows/m).
(Equation 1641)
where N_{i} and d_{i} in Equation 1641 are for cohesionless soil, cohesive soil and rock layers.
(Equation 1642)
where:
Use d_{i} and N_{i} for cohesionless soil layers only in Equation 1642.
d_{s} = The total thickness of cohesionless soil layers in the top 100 feet (30 480 mm).
m = The number of cohesionless soil layers in the top 100 feet (30 480 mm).
s_{ui} = The undrained shear strength in psf (kPa), not to exceed 5,000 psf (240 kPa), ASTM D 2166 or D 2850.
(Equation 1643)
d_{c} = The total thickness of cohesive soil layers in the top 100 feet (30 480 mm).
k = The number of cohesive soil layers in the top 100 feet (30 480 mm).
PI = The plasticity index, ASTM D 4318.
w = The moisture content in percent, ASTM D 2216.
Where a site does not qualify under the criteria for Site Class F and there is a total thickness of soft clay greater than 10 feet (3048 mm) where a soft clay layer is defined by:< 500 psf (24 kPa), w ≥ 40 percent, and PI > 20, it shall be classified as Site Class E.
The shear wave velocity for rock, Site Class B, shall be either measured on site or estimated by a geotechnical engineer or engineering geologist/seismologist for competent rock with moderate fracturing and weathering. Softer and more highly fractured and weathered rock shall either be measured on site for shear wave velocity or classified as Site Class C.
The hard rock category, Site Class A, shall be supported by shear wave velocity measurements either on site or on profiles of the same rock type in the same formation with an equal or greater degree of weathering and fracturing. Where hard rock conditions are known to be continuous to a depth of 100 feet (30 480 mm), surficial shear wave velocity measurements are permitted to be extrapolated to assess .
The rock categories, Site Classes A and B, shall not be used if there is more than 10 feet (3048 mm) of soil between the rock surface and the bottom of the spread footing or mat foundation.
TABLE 1613.5.5
SITE CLASSIFICATION^{a}
 or 
 
E  < 600 ft/s  < 15  < 1,000 psf 
D  600 to 1,200 ft/s  15 to 50  1,000 to 2,000 psf 
C  1,200 to 2,500 ft/s  > 50  > 2,000 
For SI: 1 foot per second = 304.8 mm per second, 1 pound per square foot = 0.0479 kN/m^{2}.
a. If the method is used and the and criteria differ, select the category with the softer soils (for example, use Site Class E instead of D).
1. Check for the four categories of Site Class F requiring sitespecific evaluation. If the site corresponds to any of these categories, classify the site as Site Class F and conduct a sitespecific evaluation.
2. Check for the existence of a total thickness of soft clay > 10 feet (3048 mm) where a soft clay layer is defined by: < 500 psf (24 kPa), w ≥ 40 percent and PI > 20. If these criteria are satisfied, classify the site as Site Class E.
3. Categorize the site using one of the following three methods with , , and and computed in all cases as specified.
3.1. for the top 100 feet (30 480 mm) (method).
3.2. for the top 100 feet (30 480 mm) (method).
3.3.for cohesionless soil layers (PI < 20) in the top 100 feet (30 480 mm) and average, for cohesive soil layers (PI > 20) in the top 100 feet (30 480 mm) (method).
Structures classified as Occupancy Category I, II or III that are located where the mapped spectral response acceleration parameter at 1second period, S_{1}, is greater than or equal to 0.75 shall be assigned to Seismic Design Category E. Structures classified as Occupancy Category IV that are located where the mapped spectral response acceleration parameter at 1second period, S_{1}, is greater than or equal to 0.75 shall be assigned to Seismic Design Category F. All other structures shall be assigned to a seismic design category based on their occupancy category and the design spectral response acceleration coefficients, S_{DS} and S_{D1}, determined in accordance with Section 1613.5.4 or the site specific procedures of ASCE 7. Each building and structure shall be assigned to the more severe seismic design category in accordance with Table 1613.5.6(1) or 1613.5.6(2), irrespective of the fundamental period of vibration of the structure, T.
TABLE 1613.5.6(1)
SEISMIC DESIGN CATEGORY BASED ON
SHORTPERIOD RESPONSE ACCELERATIONS
VALUE OF S_{DS}  
I or II  III  IV  
S_{DS} < 0.167g  A  A  A 
0.167g ≤ S_{DS} < 0.33g  B  B  C 
0.33g ≤ S_{DS} < 0.50g  C  C  D 
0.50g ≤ S_{DS}  D  D  D 
TABLE 1613.5.6(2)
SEISMIC DESIGN CATEGORY BASED ON
1SECOND PERIOD RESPONSE ACCELERATION
VALUE OF S_{D1}  
I or II  III  IV  
S_{D1} < 0.067g  A  A  A 
0.067g ≤ S_{D1} < 0.133g  B  B  C 
0.133g ≤ S_{D1} < 0.20g  C  C  D 
0.20g ≤ S_{D1}  D  D  D 
Where S_{1} is less than 0.75, the seismic design category is permitted to be determined from Table 1613.5.6(1) alone when all of the following apply:
 In each of the two orthogonal directions, the approximate fundamental period of the structure, Ta, in each of the two orthogonal directions determined in accordance with Section 12.8.2.1 of ASCE 7, is less than 0.8 T_{s} determined in accordance with Section 11.4.5 of ASCE 7.
 In each of the two orthogonal directions, the fundamental period of the structure used to calculate the story drift is less than T_{s}.
 Equation 12.82 of ASCE 7 is used to determine the seismic response coefficient, C_{s}.
 The diaphragms are rigid as defined in Section 12.3.1 of ASCE 7 or, for diaphragms that are flexible, the distances between vertical elements of the seismicforceresisting system do not exceed 40 feet (12 192 mm).
Add the following text at the end of Section 12.3.1.1 of ASCE 7.
Diaphragms constructed of wood structural panels or untopped steel decking shall also be permitted to be idealized as flexible, provided all of the following conditions are met:
 Toppings of concrete or similar materials are not placed over wood structural panel diaphragms except for nonstructural toppings no greater than 1^{1}/_{2} inches (38 mm) thick.
 Each line of vertical elements of the seismicforceresisting system complies with the allowable story drift of Table 12.121.
 Vertical elements of the seismicforceresisting system are lightframe walls sheathed with wood structural panels rated for shear resistance or steel sheets.
 Portions of wood structural panel diaphragms that cantilever beyond the vertical elements of the lateralforceresisting system are designed in accordance with Section 4.2.5.2 of AF&PA SDPWS.
 The value of R_{I} as defined in Chapter 17 is taken as 1.
 For OMFs and OCBFs, design is in accordance with AISC 341.
Add the following text at the end of Section 12.2.1 of ASCE 7:
For ordinary reinforced AAC masonry shear walls used in the seismicforceresisting system of structures, the response modification factor, R, shall be permitted to be taken as 2, the deflection amplification factor, C_{d}, shall be permitted to be taken as 2 and the system overstrength factor, W_{o}, shall be permitted to be taken as 2^{1}/_{2}. Ordinary reinforced AAC masonry shear walls shall not be limited in height for buildings assigned to Seismic Design Category B, shall be limited in height to 35 feet (10 668 mm) for buildings assigned to Seismic Design Category C and are not permitted for buildings assigned to Seismic Design Categories D, E and F.
For ordinary plain (unreinforced) AAC masonry shear walls used in the seismicforceresisting system of structures, the response modification factor, R, shall be permitted to be taken as 1^{1}/_{2}, the deflection amplification factor, C_{d}, shall be permitted to be taken as 1^{1}/_{2} and the system overstrength factor, W_{o}, shall be permitted to be taken as 2^{1}/_{2}. Ordinary plain (unreinforced) AAC masonry shear walls shall not be limited in height for buildings assigned to Seismic Design Category B and are not permitted for buildings assigned to Seismic Design Categories C, D, E and F.
Modify Section 12.2.5.4 of ASCE 7 to read as follows:
12.2.5.4 Increased building height limit for steel braced frames, special steel plate shear walls and special reinforced concrete shear walls. The height limits in Table 12.21 are permitted to be increased from 160 feet (48 768 mm) to 240 feet (75 152 mm) for structures assigned to Seismic Design Category D or E and from 100 feet (30 480 mm) to 160 feet (48 768 mm) for structures assigned to Seismic Design Category F that have steelbraced frames, special steel plate shear walls or special reinforced concrete castinplace shear walls and that meet both of the following requirements:
 The structure shall not have an extreme torsional irregularity as defined in Table 12.21 (horizontal structural irregularity Type 1b).
 The braced frames or shear walls in any one plane shall resist no more than 60 percent of the total seismic forces in each direction, neglecting accidental torsional effects.
All buildings and structures shall be separated from adjoining structures. Separations shall allow for the maximum inelastic response displacement (_{M}). _{M} shall be determined at critical locations with consideration for both translational and torsional displacements of the structure using Equation 1644.
(Equation 1644)
where:
C_{d} = Deflection amplification factor in Table 12.21 of ASCE 7.
_{max} = Maximum displacement defined in Section 12.8.4.3 of ASCE 7.
I = Importance factor in accordance with Section 11.5.1 of ASCE 7.
Adjacent buildings on the same property shall be separated by a distance not less than d_{MT}, determined by Equation 1645.
(Equation 1645)
where:
_{M1} , _{M2}= The maximum inelastic response displacements of the adjacent buildings in accordance with Equation 1644.
Where a structure adjoins a property line not common to a public way, the structure shall also be set back from the property line by not less than the maximum inelastic response displacement, d_{M}, of that structure.
Exceptions:
 Smaller separations or property line setbacks shall be permitted when justified by rational analyses.
 Buildings and structures assigned to Seismic Design Category A, B or C.
_{p} = 1.5. Seismic supports are not required for HVAC ductwork with I_{p} = 1.5 if either of the following conditions is met for the full length of each duct run:
 HVAC ducts are suspended from hangers 12 inches (305 mm) or less in length with hangers detailed to avoid significant bending of the hangers and their attachments, or
 HVAC ducts have a crosssectional area of less than 6 square feet (0.557 m^{2})..
1613.7 ASCE 7, Section 11.7.5. Modify ASCE 7, Section 11.7.5 to read as follows:
11.7.5 Anchorage of walls. Walls shall be anchored to the roof and all floors and members that provide lateral support for the wall or that are supported by the wall. The anchorage shall provide a direct connection between the walls and the roof or floor construction. The connections shall be capable of resisting the forces specified in Section 11.7.3 applied horizontally, substituted for E in load combinations of Section 2.3 or 2.4.
The following words and terms shall, for the purposes of Section 1614, have the meanings shown herein.
BEARING WALL STRUCTURE. A building or other structure in which vertical loads from floors and roofs are primarily supported by walls.
FRAME STRUCTURE. A building or other structure in which vertical loads from floors and roofs are primarily supported by columns.
Frame structures constructed primarily of reinforced or prestressed concrete, either castinplace or precast, or a combination of these, shall conform to the requirements of ACI 318 Sections 7.13, 13.3.8.5, 13.3.8.6, 16.5, 18.12.6, 18.12.7 and 18.12.8 as applicable. Where ACI 318 requires that nonprestressed reinforcing or prestressing steel pass through the region bounded by the longitudinal column reinforcement, that reinforcing or prestressing steel shall have a minimum nominal tensile strength equal to twothirds of the required oneway vertical strength of the connection of the floor or roof system to the column in each direction of beam or slab reinforcement passing through the column.
Exception: Where concrete slabs with continuous reinforcing having an area not less than 0.0015 times the concrete area in each of two orthogonal directions are present and are either monolithic with or equivalently bonded to beams, girders or columns, the longitudinal reinforcing or prestressing steel passing through the column reinforcement shall have a nominal tensile strength of onethird of the required oneway vertical strength of the connection of the floor or roof system to the column in each direction of beam or slab reinforcement passing through the column.
End connections of all beams and girders shall have a minimum nominal axial tensile strength equal to the required vertical shear strength for allowable stress design (ASD) or twothirds of the required shear strength for load and resistance factor design (LRFD) but not less than 10 kips (45 kN). For the purpose of this section, the shear force and the axial tensile force need not be considered to act simultaneously.
Exception: Where beams, girders, open web joist and joist girders support a concrete slab or concrete slab on metal deck that is attached to the beam or girder with not less than ^{3}/_{8}inchdiameter (9.5 mm) headed shear studs, at a spacing of not more than 12 inches (305 mm) on center, averaged over the length of the member, or other attachment having equivalent shear strength, and the slab contains continuous distributed reinforcement in each of two orthogonal directions with an area not less than 0.0015 times the concrete area, the nominal axial tension strength of the end connection shall be permitted to be taken as half the required vertical shear strength for ASD or onethird of the required shear strength for LRFD, but not less than 10 kips (45 kN).
Bearing wall structures shall have vertical ties in all loadbearing walls and longitudinal ties, transverse ties and perimeter ties at each floor level in accordance with this section and as shown in Figure 1614.4.
FIGURE 1614.4
LONGITUDINAL, PERIMETER, TRANSVERSE AND VERTICAL TIES
Longitudinal ties shall consist of continuous reinforcement in slabs; continuous or spliced decks or sheathing; continuous or spliced members framing to, within or across walls; or connections of continuous framing members to walls. Longitudinal ties shall extend across interior loadbearing walls and shall connect to exterior loadbearing walls and shall be spaced at not greater than 10 feet (3038 mm) on center. Ties shall have a minimum nominal tensile strength, T_{T}, given by Equation 1646. For ASD the minimum nominal tensile strength shall be permitted to be taken as 1.5 times the allowable tensile stress times the area of the tie.
T_{T} = wLS ≤ α_{T}S (Equation 1646)
where:
L = The span of the horizontal element in the direction of the tie, between bearing walls, feet (m).
w = The weight per unit area of the floor or roof in the span being tied to or across the wall, psf (N/m^{2}).
S = The spacing between ties, feet (m).
α_{T} = A coefficient with a value of 1,500 pounds per foot (2.25 kN/m) for masonry bearing wall structures and a value of 375 pounds per foot (0.6 kN/m) for structures with bearing walls of coldformed steel lightframe construction.
Perimeter ties shall consist of continuous reinforcement in slabs; continuous or spliced decks or sheathing; continuous or spliced members framing to, within or across walls; or connections of continuous framing members to walls. Ties around the perimeter of each floor and roof shall be located within 4 feet (1219 mm) of the edge and shall provide a nominal strength in tension not less than T_{p}, given by Equation 1647. For ASD the minimum nominal tensile strength shall be permitted to be taken as 1.5 times the allowable tensile stress times the area of the tie.
T_{p} = 200w ≤ β_{T} (Equation 1647)
For SI:
T_{p} = 90.7w ≤ β_{T} F
where:
w = As defined in Section 1614.4.2.1.
β_{T} = A coefficient with a value of 16,000 pounds (7200 kN) for structures with masonry bearing walls and a value of 4,000 pounds (1300 kN) for structures with bearing walls of coldformed steel lightframe construction.