The provisions of this chapter shall govern the
structural design of buildings, structures and portions thereof
regulated by this code.
The following terms are defined in Chapter 2:
ALLOWABLE STRESS DESIGN.
DEAD LOADS.
DESIGN STRENGTH.
DIAPHRAGM. ESSENTIAL FACILITIES.
FABRIC PARTITION.
FACTORED LOAD.
HELIPAD.
ICE-SENSITIVE STRUCTURE.
IMPACT LOAD.
LIMIT STATE.
LIVE LOAD.
LIVE LOAD (ROOF).
LOAD AND RESISTANCE FACTOR DESIGN (LRFD).
LOAD EFFECTS.
LOAD FACTOR.
LOADS.
NOMINAL LOADS.
OTHER STRUCTURES.
PANEL (PART OF A STRUCTURE).
RESISTANCE FACTOR.
RISK CATEGORY.
STRENGTH, NOMINAL.
STRENGTH, REQUIRED.
STRENGTH DESIGN.
SUSCEPTIBLE BAY.
VEHICLE BARRIER.
NOTATIONS.
ALLOWABLE STRESS DESIGN.
DEAD LOADS.
DESIGN STRENGTH.
DIAPHRAGM. ESSENTIAL FACILITIES.
FABRIC PARTITION.
FACTORED LOAD.
HELIPAD.
ICE-SENSITIVE STRUCTURE.
IMPACT LOAD.
LIMIT STATE.
LIVE LOAD.
LIVE LOAD (ROOF).
LOAD AND RESISTANCE FACTOR DESIGN (LRFD).
LOAD EFFECTS.
LOAD FACTOR.
LOADS.
NOMINAL LOADS.
OTHER STRUCTURES.
PANEL (PART OF A STRUCTURE).
RESISTANCE FACTOR.
RISK CATEGORY.
STRENGTH, NOMINAL.
STRENGTH, REQUIRED.
STRENGTH DESIGN.
SUSCEPTIBLE BAY.
VEHICLE BARRIER.
NOTATIONS.
| D | = | Dead load. |
| Di |
= | Weight of ice in accordance with Chapter 10 of ASCE 7. |
| 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 well-defined pressures and maximum heights. |
| Fa | = | 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 | = | Roof live load greater than 20 psf (0.96 kN/m2) and floor live load. |
| Lr |
= | Roof live load of 20 psf (0.96 kN/m2) or less. |
| R | = | Rain load. |
| S | = | Snow load. |
| T | = | Self-straining load. |
| Vasd |
= | Nominal design wind speed (3-second gust), miles per hour (mph) (km/hr) where applicable. |
| Vult |
= | Ultimate design wind speeds (3-second gust), miles per hour (mph) (km/hr) determined from Figure 1609.3(1), 1609.3(2), 1609.3(3) or ASCE 7. |
| W |
= | Load due to wind pressure. |
| Wi |
= | Wind-on-ice in accordance with Chapter 10 of ASCE 7. |
Construction documents shall show the size,
section and relative locations of structural members with
floor levels, column centers and offsets dimensioned. The
design loads and other information pertinent to the structural
design required by Sections 1603.1.1 through 1603.1.8 shall
be indicated on the construction documents.
Exception: Construction documents for buildings constructed
in accordance with the conventional light-frame
construction provisions of Section 2308 shall indicate the
following structural design information:
- Floor and roof Iive loads.
- Ground snow load, Pg.
- Ultimate design wind speed, Vult,(3-second gust), miles per hour (mph) (km/hr) and nominal design wind speed, Vasd, as determined in accordance with Section 1609.3.1 and wind exposure.
- Seismic design category and site class.
- Flood design data, if located in flood hazard areas established in Section 1612.3.
- Design load-bearing values of soils.
The uniformly distributed, concentrated
and impact floor live load used in the design
shall be indicated for floor areas. Use of live load reduction
in accordance with Section 1607.10 shall be indicated
for each type of live load used in the design.
The roof live load used in the
design shall be indicated for roof areas (Section 1607.12).
The ground snow load, Pg,
shall be indicated. In areas where the ground snow load,
Pg, exceeds 10 pounds per square foot (psf) (0.479 kN/m2),
the following additional information shall also be provided,
regardless of whether snow loads govern the design
of the roof:
- Flat-roof snow load, Pf.
- Snow exposure factor, Ce.
- Snow load importance factor, Is.
- Thermal factor, Ct
- Drift surcharge load(s), Pd, where the sum of Pd and Pf exceeds 20 psf (0.96 kN/m2).
- Width of snow drift(s), w.
The following information
related to wind loads shall be shown, regardless of
whether wind loads govern the design of the lateral force-resisting
system of the structure:
- Ultimate design wind speed, Vult, (3-second gust), miles per hour (km/hr) and nominal design wind speed, Vasd, as determined in accordance with Section 1609.3.1.
- Risk category.
- Wind exposure. Applicable wind direction if more than one wind exposure is utilized.
- Applicable internal pressure coefficient.
- Design wind pressures to be used for exterior component and cladding materials not specifically designed by the registered design professional responsible for the design of the structure, psf (kN/m2).
The following information
related to seismic loads shall be shown, regardless
of whether seismic loads govern the design of the lateral
force-resisting system of the structure:
- Risk category.
- Seismic importance factor, Ie.
- Mapped spectral response acceleration parameters, S5 and S1
- Site class.
- Design spectral response acceleration parameters, SDS and SDI
- Seismic design category.
- Basic seismic force-resisting system(s).
- Design base shear(s).
- Seismic response coefficient(s), CS.
- Response modification coefficient(s), R.
- Analysis procedure used.
The design load-bearing
values of soils shall be shown on the construction
documents.
For buildings located in
whole or in part in flood hazard areas as established in
Section 1612.3, the documentation pertaining to design, if
required in Section 1612.5, shall be included and the following
information, referenced to the datum on the community's
Flood Insurance Rate Map (FIRM), shall be
shown, regardless of whether flood loads govern the
design of the building:
- Flood design class assigned according to ASCE 24.
- In flood hazard areas other than coastal high hazard areas or coastal A zones, the elevation of the proposed lowest floor, including the basement.
- In flood hazard areas other than coastal high hazard areas or coastal A zones, the elevation to which any nonresidential building will be dry floodproofed.
- In coastal high hazard areas and coastal A zones, the proposed elevation of the bottom of the lowest horizontal structural member of the lowest floor, including the basement.
Special loads that are applicable
to the design of the building, structure or portions thereof
shall be indicated along with the specified section of this
code that addresses the special loading condition.
The dead load
of rooftop-mounted photovoltaic panel systems, including
rack support systems, shall be indicated on the construction
documents.
Building, structures and parts thereof shall
be designed and constructed in accordance with strength
design, load and resistance factor design, allowable stress
design, empirical design or conventional construction methods,
as permitted by the applicable material chapters.
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.
Loads and forces for occupancies or uses not covered in this chapter shall be subject to the approval of the building official.
Structural systems and members
thereof shall be designed to have adequate stiffness to limit
deflections and lateral drift. See Section 12.12.1 of ASCE 7
for drift limits applicable to earthquake loading.
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.
For SI: 1 foot = 304.8 mm.
| CONSTRUCTION | L | S or W f |
D+ Ld, g | |
|---|---|---|---|---|
| Roof members:e Supporting plaster or stucco ceiling Supporting nonplaster ceiling Not supporting ceiling |
l/360 l/240 l/180 |
l/360 l/240 l/180 |
l/240 l/180 l/120 |
|
| Floor members | l/360 | - | l/240 | |
| Exterior walls: With plaster or stucco finishes With other brittle finishes With flexible finishes |
- - - |
l/360 l/240 l/120 |
- - - |
|
| Interior partitions:b With plaster or stucco finishes With other brittle finishes With flexible finishes |
l/360 l/240 l/120 |
- - - |
- - - |
|
| Farm buildings | - | - | l/180 | |
| Greenhouses | - | - | l/120 | |
- 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.
- 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 1607.14.
- See Section 2403 for glass supports.
- The deflection limit for the D+L load combination only applies to the deflection due to the creep component of long-term dead load deflection plus the short-term live load deflection. For wood structural members that are dry at time of installation and used under dry conditions in accordance with the ANSI/AWC NDS, the creep component of the long-term deflection shall be permitted to be estimated as the immediate dead load deflection resulting from 0.5D. For wood structural members at all other moisture conditions, the creep component of the long-term deflection is per mitted to be estimated as the immediate dead load deflection resulting from D. The value of 0.5D shall not be used in combination with ANSI/AWC NDS provisions for long-term loading.
- The above deflections do not ensure against ponding. Roofs that do not have sufficient slope or camber to ensure 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 0.42 times the "component and cladding" loads for the purpose of determining deflection limits here in. Where members support glass in accordance with Section 2403 using the deflection limit therein, the wind load shall be no less than 0.6 times the "component and cladding" loads for the purpose of determining deflection.
- 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 sun room 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.
The deflection of reinforced
concrete structural members shall not exceed that
permitted by ACI 318.
The deflection of steel structural members
shall not exceed that permitted by AISC 360, AISI S100,
ASCE 8, SJI CJ, SJI JG, SJI K or SJI LH/DLH, as applicable.
The deflection of masonry structural
members shall not exceed that permitted by TMS 402/ACI
530/ASCE 5.
The deflection of aluminum structural
members shall not exceed that permitted by AA
ADM1.
The deflection limits of Section 1604.3.1
shall be used unless more restrictive deflection limits are
required by a referenced standard for the element or finish
material.
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 long-term
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 well-established 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 load-resisting elements.
The total lateral force shall be distributed to the various vertical elements of the lateral force-resisting 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 lateral force-resisting 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. 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. Where required by ASCE 7, 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 lateral force-resisting 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.
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 well-established 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 load-resisting elements.
The total lateral force shall be distributed to the various vertical elements of the lateral force-resisting 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 lateral force-resisting 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. 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. Where required by ASCE 7, 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 lateral force-resisting 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 a risk category in accordance with Table 1604.5.
Where a referenced standard specifies an occupancy category,
the risk category shall not be taken as lower than the
occupancy category specified therein. Where a referenced
standard specifies that the assignment of a risk category be in
accordance with ASCE 7, Table 1.5-1, Table 1604.5 shall be
used in lieu of ASCE 7, Table 1.5-1.
| RISK CATEGORY | 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 Risk 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:
|
| IV | Buildings and other structures designated as essential facilities, including but not limited to:
|
- For purposes of occupant load calculation, occupancies required by Table 1004.1.2 to use gross floor area calculations shall be permitted to use net floor areas to determine the total occupant load.
- Where approved by the building official, the classification of buildings and other structures as Risk Category III or IV based on their quantities of toxic, highly toxic or explosive materials is permitted to be reduced to Risk Category II, provided it can be demonstrated by a hazard assessment in accordance with Section 1.5.3 of ASCE 7 that a release of the toxic, highly toxic or explosive materials is not sufficient to pose a threat to the public.
Where a building or
structure is occupied by two or more occupancies not
included in the same risk category, it shall be assigned the
classification of the highest risk category corresponding to
the various occupancies. Where buildings or structures
have two or more portions that are structurally separated,
each portion shall be separately classified. Where a separated
portion of a building or structure provides required
access to, required egress from or shares life safety components
with another portion having a higher risk category,
both portions shall be assigned to the higher risk
category.
The building official is authorized
to require an engineering analysis or a load test, or both, of
any construction whenever there is reason to question the
safety of the construction for the intended occupancy. Engineering
analysis and load tests shall be conducted in accordance
with Section 1708.
Materials and methods of
construction that are not capable of being designed by approved engineering analysis or that do not comply with the
applicable referenced standards, or alternative test procedures
in accordance with Section 1707, shall be load tested in
accordance with Section 1719.
Buildings and other structures, and portions
thereof, shall be provided with anchorage in accordance
with Sections 1604.8.1 through 1604.8.3, as applicable.
Walls that provide vertical
load-bearing resistance or lateral shear resistance for a
portion of the structure shall be anchored to the roof and to
all floors and members that provide lateral support for the
wall or that are supported by the wall. The connections
shall be capable of resisting the horizontal forces specified
in Section 1.4.5 of ASCE 7 for walls of structures assigned
to Seismic Design Category A and to Section 12.11 of
ASCE 7 for walls of structures assigned to all other seismic
design categories. Required anchors in masonry walls
of hollow units or cavity walls shall be embedded in a
reinforced grouted structural element of the wall. See Sections
1609 for wind design requirements and 1613 for
earthquake design requirements.
Where supported by attachment to an
exterior wall, decks shall be positively anchored to the primary
structure and designed for both vertical and lateral
loads as applicable. Such attachment shall not be accomplished
by the use of toenails or nails subject to withdrawal.
Where positive connection to the primary building
structure cannot be verified during inspection, decks shall
be self-supporting. Connections of decks with cantilevered
framing members to exterior walls or other framing members
shall be designed for both of the following:
(continued)
- 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.
| OCCUPANCY OR USE | UNIFORM (psf) | CONCENTRATED (pounds) |
|---|---|---|
| 1. Apartments (see residential) | — | — |
| 2. Access floor systems | ||
Office use |
50 | 2,000 |
Computer use |
100 | 2,000 |
| 3. Armories and drill rooms | 150m | — |
| 4. Assembly areas | — | |
Fixed seats (fastened to floor) |
60m | |
Follow spot, projections and control rooms |
50 | |
Lobbies |
100m | |
Movable seats |
100m | |
Stage floors |
150m | |
Platforms (assembly) |
100m | |
Other assembly areas |
100m | |
| 5. Balconies and decksh | Same as occupancy served | — |
| 6. Catwalks | 40 | 300 |
| 7. Cornices | 60 | — |
| 8. Corridors | — | |
First floor |
100 | |
Other floors |
Same as occupancy served except as indicated |
|
| 9. Dining rooms and restaurants | 100m | — |
| 10. Dwellings (see residential) | — | — |
| 11. Elevator machine room and control room grating (on area of 2 inches by 2 inches) |
— | 300 |
| 12. Finish light floor plate construction (on area of 1 inch by 1 inch) |
— | 200 |
| 13. Fire escapes | 100 | — |
On single-family dwellings only |
40 | |
| 14. Garages (passenger vehicles only) | 40m | Note a |
Trucks and buses |
See Section 1607.7 | |
| 15. Handrails, guards and grab bars | See Section 1607.8 | |
| 16. Helipads | See Section 1607.6 | |
| 17. Hospitals | ||
Corridors above first floor |
80 | 1,000 |
Operating rooms, laboratories |
60 | 1,000 |
Patient rooms |
40 | 1,000 |
| 18. Hotels (see residential) | — | — |
| 19. Libraries | ||
Corridors above first floor |
80 | 1,000 |
Reading rooms |
60 | 1,000 |
Stack rooms |
150b, m | 1,000 |
| 20. Manufacturing | ||
Heavy |
250m | 3,000 |
Light |
125m | 2,000 |
| 21. Marquees, except one- and two-family dwellings | 75 | — |
| 22. Office buildings | ||
Corridors above first floor |
80 | 2,000 |
File and computer rooms shall be designed for heavier loads based on anticipated occupancy |
— | — |
Lobbies and first-floor corridors |
100 | 2,000 |
Offices |
50 | 2,000 |
(continued)
| OCCUPANCY OR USE | UNIFORM (psf) | CONCENTRATED (pounds) |
|---|---|---|
| 23. Penal institutions | — | |
Cell blocks |
40 | |
| 100 | ||
| 24. Recreational uses: | — | |
Bowling alleys, poolrooms and similar uses |
75m | |
Dance halls and ballrooms |
100m | |
Gymnasiums |
100m | |
Ice skating rink |
250m | |
Reviewing stands, grandstands and bleachers |
100c, m | |
Roller skating rink |
100m | |
Stadiums and arenas with fixed seats (fastened to floor) |
60c, m | |
| 25. Residential | — | |
One- and two-family dwellings |
||
Uninhabitable attics without storagei |
10 | |
Uninhabitable attics with storagei, j, k |
20 | |
Habitable attics and sleeping areask |
30 | |
| 20 | ||
All other areas |
40 | |
Hotels and multi-family dwellings |
||
Private rooms and corridors serving them |
40 | |
Public roomsm and corridors serving them |
100 | |
| 26. Roofs | ||
All roof surfaces subject to maintenance workers |
300 | |
Fabric construction supported by a skeleton structure |
5 Nonreducible |
|
All other construction, except one- and two-family dwellings |
20 | |
Ordinary flat, pitched, and curved roofs (that are not occupiable) |
20 | |
Primary roof members exposed to a work floor |
||
| 2,000 | ||
All other primary roof members |
300 | |
Occupiable roofs: |
||
Roof gardens |
100 | |
Assembly areas |
100m | |
All other similar areas |
Note 1 | Note 1 |
| 27. Schools | ||
Classrooms |
40 | 1,000 |
Corridors above first floor |
80 | 1,000 |
First-floor corridors |
100 | 1,000 |
| 28. Scuttles, skylight ribs and accessible ceilings | — | 200 |
| 29. Sidewalks, vehicular driveways and yards, subject to trucking | 250d, m | 8,000e |
| 30. Stairs and exits | ||
One- and two-family dwellings |
40 | 300f |
All other |
100 | 300f |
| 31. Storage warehouses (shall be designed for heavier loads if required for anticipated storage) | — | |
Heavy |
250m | |
Light |
125m | |
| 32. Stores | ||
Retail |
||
First floor |
100 | 1,000 |
Upper floors |
75 | 1,000 |
Wholesale, all floors |
125m | 1,000 |
| 33. Vehicle barriers | See Section 1607.8.3 | |
| 34. Walkways and elevated platforms (other than exitways) | 60 | — |
| 35. Yards and terraces, pedestrians | 100m | — |
For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2,
1 square foot = 0.0929 m2,
1 pound per square foot = 0.0479 kN/m2,
1 pound = 0.004448 kN,
1 pound per cubic foot = 16 kg/m3.
1 square foot = 0.0929 m2,
1 pound per square foot = 0.0479 kN/m2,
1 pound = 0.004448 kN,
1 pound per cubic foot = 16 kg/m3.
- Floors in garages or portions of buildings used for the storage of motor vehicles shall be designed for the uniformly distributed live loads of this Table 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 1/2 inches by 4 1/2 inches; (2) for mechanical parking structures without slab or deck that are used for storing passenger vehicles only, 2,250 pounds per wheel.
- The loading applies to stack room floors that support nonmobile, double - faced library book stacks, subject to the following limitations:
- Design in accordance with ICC 300.
- Other uniform loads in accordance with an approved method containing provisions for truck loadings shall be considered where appropriate.
- The concentrated wheel load shall be app lied on an area of 4.5 inches by 4.5 inches.
- The minimum concentrated load on stair treads shall be applied on an area of 2 inches by 2 inches. This load need not be assumed to act concurrently with the uniform load.
- 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).
- See Section 1604.8.3 for decks attached to exterior walls.
- Uninhabitable attics without storage are those where the maximum clear height between the joists and rafters is less than 42 inches, or where there are not two or more adjacent trusses with web configurations capable of accommodating an assumed rectangle 42 inches in height by 24 inches in width, or greater, within the plane of the trusses. This live load need not be assumed to act concurrently with any other live load requirements.
- Uninhabitable attics with storage are those where the maximum clear
height between the joists and rafters is 42 inches or greater, or where
there are two or more adjacent trusses with web configurations capable
of accommodating an assumed rectangle 42 inches in height by 24 inches
in width, or greater, within the plane of the trusses.
The live load need only be applied to those portions of the joists or truss bottom chords where both of the following conditions are met:- The attic area is accessible from an opening not less than 20 inches in width by 30 inches in length that is located where the clear height in the attic is a minimum of 30 inches; and
- The slopes of the joists or truss bottom chords are no greater than two units vertical in 12 units horizontal.
- Attic spaces served by stairways other than the pull-down type shall be designed to support the minimum live load specified for habitable attics and sleeping rooms.
- Areas of occupiable roofs, other than roof gardens and assembly areas, shall be designed for appropriate loads as approved by the building official. Unoccupied landscaped areas of roofs shall be designed in accordance with Section 1607.12.3.
- Live load reduction is not permitted unless specific exceptions of Section 1607.10 apply.
Structural members,
systems, components and cladding shall be designed to
resist forces due to earthquakes and wind, with consideration
of overturning, sliding and uplift. Continuous load paths shall
be provided for transmitting these forces to the foundation.
Where sliding is used to isolate the elements, the effects of
friction between sliding elements shall be included as a force.
Lateral force-resisting
systems shall meet seismic detailing requirements and limitations
prescribed in this code and ASCE 7, excluding Chapter
14 and Appendix 11A, even when wind load effects are
greater than seismic load effects.
Buildings and other structures and portions
thereof shall be designed to resist:
Where the load combinations with overstrength factor in Section 12.4.3.2 of ASCE 7 apply, they shall be used as follows:
- 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 seismic load effects including overstrength factor in accordance with Section 12.4.3 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 seismic load effects including overstrength factor in accordance with 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 over strength factor in lieu of Equations 16-5 and 16-7 in Section 1605.2.
- The basic combinations for allowable stress design with overstrength factor in lieu of Equations 16-12, 16- 14 and 16-16 in Section 1605.3.1.
- The basic combinations for allowable stress design with over strength factor in lieu of Equations 16-21 and 16-22 in Section 1605.3.2.
Regardless of which load combinations
are used to design for strength, where overall structure
stability (such as stability against overturning, sliding,
or buoyancy) is being verified, use of the load combinations
specified in Section 1605.2 or 1605.3 shall be permitted.
Where the load combinations specified in Section
1605.2 are used, strength reduction factors applicable to
soil resistance shall be provided by a registered design
professional. The stability of retaining walls shall be verified
in accordance with Section 1807.2.3.
Where strength design or load
and resistance factor design is used, buildings and other structures,
and portions thereof, shall be designed to resist the
most critical effects resulting from the following combinations
of factored loads:
Exceptions:
1.4(D +F)
(Equation 16-1)
1.2(D + F) + 1.6(L + H) + 0.5(Lr or S or R)
(Equation 16-2)
1.2(D + F) + 1.6(Lr or S or R) + 1.6H + (f1L or 0.5W)
(Equation 16-3)
(Equation 16-3)
1.2(D + F) + 1.0W + f1L + 1.6H + 0.5(Lr or S or R)
(Equation 16-4)
1.2(D + F) + 1.0E + f1L+ 1.6H + f2S
(Equation 16-5)
0.9D+ 1.0W + 1.6H
(Equation 16-6)
0.9(D + F) + 1.0E+ 1.6H
(Equation 16-7)
| where: | ||
|---|---|---|
| f1 | = | 1 for places of public assembly live loads in excess of 100 pounds per square foot (4.79 kN/m2), and parking garages; and 0.5 for other live loads. |
| f2 | = | 0.7 for roof configurations (such as saw tooth) that do not shed snow off the structure, and 0.2 for other roof configurations. |
- Where other factored load combinations are specifically required by other provisions of this code, such combinations shall take precedence.
- Where the effect of H resists the primary variable load effect, a load factor of 0.9 shall be included with H where H is permanent and H shall be set to zero for all other conditions.
Where flood loads, Fa, are to be
considered in the design, the load combinations of Section
2.3.3 of ASCE 7 shall be used. Where self-straining loads,
T, are considered in design, their structural effects in combination
with other loads shall be determined in accordance
with Section 2.3.5 of ASCE 7. Where an ice-sensitive
structure is subjected to loads due to atmospheric
icing, the load combinations of Section 2.3.4 of ASCE 7
shall be considered.
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:
Exceptions:
D + F;
(Equation 16-8)
D + H + F + L
(Equation 16-9)
D + H + F + (Lr or S or R)
(Equation 16-10)
D + H + F + 0.75(L) + 0.75(Lr or S or R)
(Equation 16-11)
D + H + F + (0.6W or 0.7E)
(Equation 16-12)
D + H + F + 0.75(0.6W) + 0.75L + 0.75(Lr or S or R)
(Equation 16-13)
D + H + F + 0.75 (0.7 E) + 0.75 L + 0.75 S
(Equation 16-14)
0.6D + 0.6W + H
(Equation 16-15)
0.6(D + F) + 0.7E +H
(Equation 16-16)
Exceptions:
- Crane hook loads need not be combined with roof live load or with more than three-fourths of the snow load or one-half of the wind load.
- Flat roof snow loads of 30 psf (1.44 kN/m2) or less and roof live loads of 30 psf (1.44 kN/m2) or less need not be combined with seismic loads. Where flat roof snow loads exceed 30 psf (1.44 kN/m2), 20 percent shall be combined with seismic loads.
- Where the effect of H resists the primary variable load effect, a load factor of 0.6 shall be included with H where H is permanent and H shall be set to zero for all other conditions.
- In Equation 16-15, the wind load, W, is permitted to be reduced in accordance with Exception 2 of Section 2.4.1 of ASCE 7.
- In Equation 16-16, 0.6 D is permitted to be increased to 0.9 D for the design of special reinforced masonry shear walls complying with Chapter 21.
Increases in allowable
stresses specified in the appropriate material chapter or
the referenced standards shall not be used with the load
combinations of Section 1605.3.1, except that increases
shall be permitted in accordance with Chapter 23.
Where flood loads, Fa, are to
be considered in design, the load combinations of Section
2.4.2 of ASCE 7 shall be used. Where self-straining
loads, T, are considered in design, their structural
effects in combination with other loads shall be determined
in accordance with Section 2.4.4 of ASCE 7.
Where an ice-sensitive structure is subjected to loads
due to atmospheric icing, the load combinations of Section
2.4.3 of ASCE 7 shall be considered.
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 two-thirds of the minimum
dead load likely to be in place during a design wind event
shall be used. When using allowable stresses that have
been increased or load combinations that have been
reduced as permitted by the material chapter of this code
or the referenced standards, where wind loads are calculated
in accordance with Chapters 26 through 31 of ASCE
7, the coefficient (ω) in the following equations shall be
taken as 1.3. For other wind loads,(ω) shall be taken as 1.
When allowable stresses have not been increased or load
combinations have not been reduced as permitted by the
material chapter of this code or the referenced standards,
(ω) shall be taken as 1. When using these alternative load
combinations to evaluate sliding, overturning and soil
bearing at the soil-structure 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, Ev, in Equation 12.4-4 of ASCE 7 is permitted to be
taken equal to zero.
Exceptions:
D + L + (Lr or S or R)
(Equation 16-17)
D + L + 0.6ωW
(Equation 16-18)
D + L + 0.6 ωW + S/2
(Equation 16-19)
D + L + S + 0.6 ωW/2
(Equation 16-20)
D + L + S + E/1.4
(Equation 16-21)
0.9D + E/1.4
(Equation 16-22)
Exceptions:
- Crane hook loads need not be combined with roof live loads or with more than three-fourths of the snow load or one-half of the wind load.
- Flat roof snow loads of 30 psf (1.44 kN/m2) or less and roof live loads of 30 psf (1.44 kN/m2) or less need not be combined with seismic loads. Where flat roof snow loads exceed 30 psf (1.44 kN/m2), 20 percent shall be combined with seismic loads.
Where F, H or Tare to be considered
in the design, each applicable load shall be
added to the combinations specified in Section
1605.3.2. Where self-straining loads, T, are considered
in design, their structural effects in combination with
other loads shall be determined in accordance with Section
2.4.4 of ASCE 7.
Dead loads are those loads defined in Chapter
2 of this code. Dead loads shall be considered permanent
loads.
For purposes of design, the actual
weights of materials of construction and fixed service equipment
shall be used. In the absence of definite information,
values used shall be subject to the approval of the building
official.
For occupancies or uses not designated
in Table 1607.1, the live load shall be determined in
accordance with a method approved by the building official.
The live loads used in the design
of buildings and other structures shall be the maximum loads
expected by the intended use or occupancy but shall in no
case be less than the minimum uniformly distributed live
loads given in Table 1607.1.
Floors and other similar
surfaces shall be designed to support the uniformly distributed
live loads prescribed in Section 1607.3 or the concentrated
live loads, given in Table 1607.1, whichever produces
the greater load effects. Unless otherwise specified, the indicated
concentration shall be assumed to be uniformly distributed
over an area of 21/2 feet by 21/2 feet (762 mm by 762
mm) and shall be located so as to produce the maximum load
effects in the structural members.
In office buildings and in other
buildings where partition locations are subject to change, provisions
for partition weight shall be made, whether or not partitions
are shown on the construction documents, unless the
specified live load is 80 psf (3.83 kN/m2) or greater. The partition
load shall be not less than a uniformly distributed live
load of 15 psf (0.72 kN/m2).
Helipads shall be designed for the following
live loads:
Landing areas designed for a design basis helicopter with
maximum take-off weight of 3,000-pounds (13.35 kN) shall be identified with a 3,000 pound (13.34 kN) weight limitation.
The landing area weight limitation shall be indicated by
the numeral "3" (kips) located in the bottom right corner of
the landing area as viewed from the primary approach path.
The indication for the landing area weight limitation shall be
a minimum 5 feet (1524 mm) in height.
- A uniform live load, L, as specified below. This load
shall not be reduced.
- 40 psf (1.92 kN/m2) where the design basis helicopter has a maximum take-off weight of 3,000 pounds (13.35 kN) or less.
- 60 psf (2.87 kN/m2) where the design basis helicopter has a maximum take-off weight greater than 3,000 pounds (13.35 kN).
- A single concentrated live load, L, of 3,000 pounds (13.35 kN) applied over an area of 4.5 inches by 4.5 inches (114 mm by 114 mm) and located so as to produce the maximum load effects on the structural elements under consideration. The concentrated load is not required to act concurrently with other uniform or concentrated live loads.
- Two single concentrated live loads. L, 8 feet (2438 mm) apart applied on the landing pad (representing the helicopter's two main landing gear, whether skid type or wheeled type), each having a magnitude of 0.75 times the maximum take-off weight of the helicopter, and located so as to produce the maximum load effects on the structural elements under consideration. The concentrated loads shall be applied over an area of 8 inches by 8 inches (203 mm by 203 mm) and are not required to act concurrently with other uniform or concentrated live loads.
Where any structure does not restrict
access for vehicles that exceed a 10,000-pound (4536 kg)
gross vehicle weight rating, those portions of the structure
subject to such loads shall be designed using the vehicular
live loads, including consideration of impact and fatigue,
in accordance with the codes and specifications required
by the jurisdiction having authority for the design and construction
of the roadways and bridges in the same location
of the structure.
Where a
structure or portions of a structure are accessed and loaded
by fire department access vehicles and other similar emergency
vehicles, the structure shall be designed for the
greater of the following loads:
- The actual operational loads, including outrigger reactions and contact areas of the vehicles as stipulated and approved by the building official; or
- The live loading specified in Section 1607.7.1.
Garages designed to
accommodate vehicles that exceed a 10,000-pound (4536
kg) gross vehicle weight rating, shall be designed using
the live loading specified by Section 1607.7.1. For
garages the design for impact and fatigue is not required.
Exception: The vehicular live loads and load placement
are allowed to be determined using the actual
vehicle weights for the vehicles allowed onto the
garage floors, provided such loads and placement are
based on rational engineering principles and are
approved by the building official, but shall not be less
than 50 psf (2.9 kN/m2). This live load shall not be
reduced.
Where a
structure is intended to have forklifts or other movable
equipment present, the structure shall be designed for the
total vehicle or equipment load and the individual wheel
loads for the anticipated vehicles as specified by the owner
of the facility. These loads shall be posted in accordance
with Section 1607.7.5.
Impact loads and
fatigue loading shall be considered in the design of the
supporting structure. For the purposes of design, the
vehicle and wheel loads shall be increased by 30 percent
to account for impact.
The maximum weight of vehicles
allowed into or on a garage or other structure shall be
posted by the owner or the owner's authorized agent in
accordance with Section 106.1.
Handrails, guards, grab bars, accessible
seats, accessible benches and vehicle barriers shall be
designed and constructed for the structural loading conditions
set forth in this section.
Handrails and guards
shall be designed to resist a linear load of 50 pounds per
linear foot (plf) (0.73 kN/m) in accordance with Section
4.5.1 of ASCE 7. Glass handrail assemblies and guards
shall also comply with Section 2407.
Exceptions:
- For one-and two-family dwellings, only the single concentrated load required by Section 1607.8.1.1 shall be applied.
- In Group I-3, F, Hand 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).
Grab bars, shower seats and dressing room
bench seats shall be designed to resist a single concentrated
load of 250 pounds (1.11 kN) applied in any direction
at any point on the grab bar or seat so as to produce
the maximum load effects.
Vehicle barriers for passenger
vehicles shall be designed to resist a concentrated load of
6,000 pounds (26.70 kN) in accordance with Section 4.5.3
of ASCE 7. Garages accommodating trucks and buses
shall be designed in accordance with an approved method
that contains provisions for traffic railings.
The live loads specified in Sections
1607.3 through 1607.8 shall be assumed to include adequate
allowance for ordinary impact conditions. Provisions shall be
made in the structural design for uses and loads that involve
unusual vibration and impact forces.
Elevator loads shall be increased by
100% for impact and the structural supports shall be
designed within the limits of deflection prescribed by the
Michigan elevator code, R 408.7001 to R 408.8695.
R408.30459
R408.30459
For the purpose of design, the
weight of machinery and moving loads shall be increased
as follows to allow for impact: (1) light machinery, shaft-or
motor-driven, 20 percent; and (2) reciprocating machinery
or power-driven units, 50 percent. Percentages shall be
increased where specified by the manufacturer.
In addition to any other applicable live loads,
structural elements that support hoists for façade access
equipment shall be designed for a live load consisting of
the larger of the rated load of the hoist times 2.5 and the
stall load of the hoist.
In addition to any other applicable live loads, lifeline
anchorages and structural elements that support
lifeline anchorages shall be designed for a live load of at
least 3,100 pounds (13.8 kN) for each attached lifeline, in
every direction that a fall arrest load may be applied.
Except for uniform
live loads at roofs, all other minimum uniformly distributed
live loads, Lo, in Table 1607.1 are permitted to be
reduced in accordance with Section 1607.10.1 or 1607.10.2.
Uniform live loads at roofs are permitted to be reduced in
accordance with Section 1607.12.2.
Subject to
the limitations of Sections 1607.10.1.1 through
1607.10.1.3 and Table 1607.1, members for which a value
of KLLAT is 400 square feet (37.16 m2) or more are permitted
to be designed for a reduced uniformly distributed live
load, L, in accordance with the following equation:
L shall be not less than 0.50Lo for members supporting
one floor and L shall be not less than 0.40Lo for members
supporting two or more floors.
| where: | ||
| L | = | Reduced design live load per square foot (m2) of area supported by the member. |
| Lo | = | Unreduced design live load per square foot (m2) of area supported by the member (see Table 1607.1). |
| KLL | = | Live load element factor (see Table 1607.10.1). |
| AT | = | Tributary area, in square feet (m2). |
| ELEMENT | KLL |
|---|---|
| Interior columns Exterior columns without cantilever slabs |
4 4 |
| Edge columns with cantilever slabs | 3 |
| Corner columns with cantilever slabs Edge beams without cantilever slabs Interior beams |
2 2 2 |
All other members not identified above including: Edge beams with cantilever slabs Cantilever beams One-way slabs Two-way slabs Members without provisions for continuous shear transfer normal to their span |
1 |
The tributary area, AT, for
use in Equation 16-23 for one-way slabs shall not
exceed an area defined by the slab span times a width
normal to the span of 1.5 times the slab span.
Live loads that exceed
100 psf (4.79 kN/m2) shall not be reduced:
Exceptions:
- 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 be not less than L as calculated in Section 1607.10.1.
- 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.
The live loads
shall not be reduced in passenger vehicle garages.
Exception: 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 1607.10.1.
As an
alternative to Section 1607.10.1 and subject to the limitations
of Table 1607.1, uniformly distributed 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 where the live
load exceeds 100 psf (4.79 kN/m2) except that the
design live load for members supporting two or
more floors is permitted to be reduced by a maximum
of 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. - 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.
- For live loads not exceeding 100 psf (4.79 kN/m2), the design live load for any structural member supporting 150 square feet (13.94 m2) or more is permitted to be reduced in accordance with Equation 16-24.
- For one-way slabs, the area, A, for use in Equation 16-24 shall not exceed the product of the slab span and a width normal to the span of 0.5 times the slab span.
- 40 percent for members supporting one floor.
- 60 percent for members supporting two or more floors.
- R as determined by the following equation:
R = 0.08(A - 150)
(Equation 16-24)
For SI: R = 0.861(A - 13.94)
Such reduction shall not exceed the smallest of:
R = 23.1 (1 + D/Lo )
(Equation 16-25)
| where: |
||
| A | = | Area of floor supported by the member, square feet (m2). |
| D |
= | Dead load per square foot (m2) of area supported. |
| Lo | = | Unreduced live load per square foot (m2) of area supported. |
| R |
= | Reduction in percent. |
Where uniform floor
live loads are involved in the design of structural members
arranged so as to create continuity, the minimum applied
loads shall be the full dead loads on all spans in combination
with the floor live loads on spans selected to produce the
greatest load effect at each location under consideration.
Floor live loads are permitted to be reduced in accordance
with Section 1607.10.
The structural supports of roofs and
marquees shall be designed to resist wind and, where applicable,
snow and earthquake loads, in addition to the dead load
of construction and the appropriate live loads as prescribed in
this section, or as set forth in Table 1607.1. The live loads
acting on a sloping surface shall be assumed to act vertically
on the horizontal projection of that surface.
Where uniform
roof live loads are reduced to less than 20 psf (0.96 kN/m2)
in accordance with Section 1607.12.2.1 and are applied to
the design of structural members arranged so as to create
continuity, the reduced roof live load shall be applied to
adjacent spans or to alternate spans, whichever produces
the most unfavorable load effect. See Section 1607.12.2
for reductions in minimum roof live loads and Section 7.5
of ASCE 7 for partial snow loading.
The minimum uniformly distributed
live loads of roofs and marquees, Lo, in Table 1607.1 are
permitted to be reduced in accordance with Section
1607.12.2.1.
Ordinary flat, pitched and curved roofs, and awnings
and canopies other than of fabric construction supported
by a skeleton structure, are permitted to be
designed for a reduced uniformly distributed roof live
load, L, as specified in the following equations or other
controlling combinations of loads as specified in Section
1605, whichever produces the greater load effect.
In structures such as greenhouses, where special scaffolding is used as a work surface for workers and materials during maintenance and repair operations, a lower roof load than specified in 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/m2).
The reduction factors R1 and R2 shall be determined as follows:
For SI: 1.2 - 0.011At for 18.58 square meters < At < 55.74 square meters
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/m2).
Lr = L0 R1 R2
(Equation 16-26)
| where: 12 ≤ Lr ≤ 20 | ||
| For SI: Lr = LoR1R2 |
||
| where: 0.58 ≤ Lr ≤ 0.96 | ||
| Lo | = | Unreduced roof live load per square foot (m2) of horizontal projection supported by the member (see Table 1607.1). |
| Lr |
= | Reduced roof live load per square foot (m2) of horizontal projection supported by the member. |
The reduction factors R1 and R2 shall be determined as follows:
R1 = 1 for At ≤ 200 square feet (18.58 m2)
(Equation 16-27)
R1 = 1.2 - 0.001At for 200 square feet
< At < 600 square feet (Equation 16-28)
< At < 600 square feet (Equation 16-28)
For SI: 1.2 - 0.011At for 18.58 square meters < At < 55.74 square meters
R1 = 0.6 for At ≥ 600 square feet (55.74 m2)
(Equation 16-29)
| where: |
||
| At | = | Tributary area (span length multiplied by effective width) in square feet (m2) supported by the member, and |
R2 = 1 for F ≤ 4
(Equation 16-30)
R2 = 1.2 - 0.05 F for 4 < F < 12
(Equation 16-31)
R2 = 0.6 for F ≥ 12
(Equation 16-32)
| where: |
||
| F |
= | For a sloped roof, the number of inches of rise per foot (for SI: F = 0.12 x slope, with slope expressed as a percentage), or for an arch or dome, the rise-to-span ratio multiplied by 32. |
Areas of roofs that are occupiable,
such as vegetative roofs, roof gardens or for assembly
or other similar purposes, and marquees are permitted
to have their uniformly distributed live loads reduced in
accordance with Section 1607.10.
Awnings and canopies
shall be designed for uniform live loads as required in
Table 1607.1 as well as for snow loads and wind loads as
specified in Sections 1608 and 1609.
Roof surfaces to be covered
by solar photovoltaic panels or modules shall be
designed for the roof live load, Lr, assuming that the
photovoltaic panels or modules are not present. The
roof photovoltaic live load in areas covered by solar
photovoltaic panels or modules shall be in addition to
the panel loading unless the area covered by each solar
photovoltaic panel or module is inaccessible. Areas
where the clear space between the panels and the rooftop
is not more than 24 inches (610 mm) shall be considered
inaccessible. Roof surfaces not covered by
photovoltaic panels shall be designed for the roof live
load.
Roof surfaces to be covered
by solar photovoltaic panels or modules shall be
designed for the roof live load, Lr, assuming that the
photovoltaic panels or modules are not present. The
roof photovoltaic live load in areas covered by solar
photovoltaic panels or modules shall be in addition to
the panel loading unless the area covered by each solar
photovoltaic panel or module is inaccessible. Areas
where the clear space between the panels and the rooftop
is not more than 24 inches (610 mm) shall be considered
inaccessible. Roof surfaces not covered by
photovoltaic panels shall be designed for the roof live
load.
The
structure of a roof that supports solar photovoltaic panels
or modules shall be designed to accommodate the
full solar photovoltaic panels or modules and ballast
dead load, including concentrated loads from support
frames in combination with the loads from Section
1607.12.5.1 and other applicable loads. Where applicable,
snow drift loads created by the photovoltaic panels
or modules shall be included.
Solar photovoltaic panels
or modules that are independent structures and do not
have accessible/occupied space underneath are not
required to accommodate a roof photovoltaic live load,
provided the area under the structure is restricted to keep
the public away. All other loads and combinations in
accordance with Section 1605 shall be accommodated.
Solar photovoltaic panels or modules that are designed to be the roof, span to structural supports and have accessible/ occupied space underneath shall have the panels or modules and all supporting structures designed to support a roof photovoltaic live load, as defined in Section 1607.12.5.1 in combination with other applicable loads. Solar photovoltaic panels or modules in this application are not permitted to be classified as "not accessible" in accordance with Section 1607.12.5.1.
Solar photovoltaic panels or modules that are designed to be the roof, span to structural supports and have accessible/ occupied space underneath shall have the panels or modules and all supporting structures designed to support a roof photovoltaic live load, as defined in Section 1607.12.5.1 in combination with other applicable loads. Solar photovoltaic panels or modules in this application are not permitted to be classified as "not accessible" in accordance with Section 1607.12.5.1.
Roof structures that provide support for ballasted photovoltaic
panel systems shall be designed, or analyzed,
in accordance with Section 1604.4; checked in accordance
with Section 1604.3.6 for deflections; and
checked in accordance with Section 1611 for ponding.
The crane live load shall be the rated
capacity of the crane. Design loads for the runway beams,
including connections and support brackets, of moving bridge
cranes and monorail cranes shall include the maximum wheel
loads of the crane and the vertical impact, lateral and longitudinal
forces induced by the moving crane.
The maximum wheel
loads 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 |
| Cab-operated or remotely operated bridge cranes (powered)...................................................................... |
25 percent |
| Pendant-operated bridge cranes (powered).................................................................................. |
10 percent |
| Bridge cranes or monorail cranes with hand-geared bridge, trolley and hoist....................................... |
0 percent |
The lateral force on crane runway
beams with electrically powered trolleys shall be calculated
as 20 percent of the sum of the rated capacity of
the crane and the weight of the hoist and trolley. The lateral
force shall be assumed to act horizontally at the traction
surface of a runway beam, in either direction
perpendicular to the beam, and shall be distributed with
due regard to the lateral stiffness of the runway beam and
supporting structure.
The longitudinal force on
crane runway beams, except for bridge cranes with hand-geared
bridges, shall be calculated as 10 percent of the
maximum wheel loads of the crane. The longitudinal force
shall be assumed to act horizontally at the traction surface
of a runway beam, in either direction parallel to the beam.
Fabric partitions that exceed
6 feet (1829 mm) in height, including their finish materials,
shall have adequate strength and stiffness to resist the
following load conditions:
- The horizontal distributed load need only be 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 8-inch-diameter (203 mm) area [50.3 square inches (32 452 mm2)] of the fabric face at a height of 54 inches (1372 mm) above the floor.
Design snow loads shall be determined in
accordance with Chapter 7 of ASCE 7, but the design roof
load shall not be less than that determined by Section 1607.
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.
Site-specific 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 2-percent annual probability of
being exceeded (50-year mean recurrence interval). Snow
loads are zero for Hawaii, except in mountainous regions as
approved by the building official.
For SI: 1 pound per square foot = 0.0479 kN/m2.
FIGURE 1608.2
GROUND SNOW LOADS
R 408.30448d
FIGURE 1608.2-Continued
GROUND SNOW LOADS
R 408.30448d
| LOCATION | POUNDS PER SQUARE FOOT |
LOCATION | POUNDS PER SQUARE FOOT |
LOCATION | POUNDS PER SQUARE FOOT |
||
|---|---|---|---|---|---|---|---|
| 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 |
GROUND SNOW LOADS
GROUND SNOW LOADS
Susceptible bays of roofs shall
be evaluated for ponding instability in accordance with Section
7.11 of ASCE 7.
Buildings, structures and parts thereof
shall be designed to withstand the minimum wind loads prescribed
herein. Decreases in wind loads shall not be made for
the effect of shielding by other structures.
Wind loads on
every building or structure shall be determined in accordance
with Chapters 26 to 30 of ASCE 7 or provisions of
the alternate all-heights method in Section 1609.6. The
type of opening protection required, the ultimate design
wind speed, Vult, and the exposure category for a site is
permitted to be determined in accordance with Section
1609 or ASCE 7. Wind shall be assumed to come from
any horizontal direction and wind pressures shall be
assumed to act normal to the surface considered.
Notes:
FIGURE 1609.3(1)
ULTIMATE DESIGN WIND SPEEDS, vult, FOR RISK CATEGORY II BUILDINGS AND OTHER STRUCTURES
Notes:
FIGURE 1609.3(2)
ULTIMATE DESIGN WIND SPEEDS, vult, FOR RISK CATEGORY I BUILDINGS AND OTHER STRUCTURES
Notes:
FIGURE 1609.3(3)
ULTIMATE DESIGN WIND SPEEDS, vult, FOR RISK CATEGORY I BUILDINGS AND OTHER STRUCTURES
Exceptions:
The wind speeds in Figures 1609.3(1), 1609.3(2) and
1609.3(3) are ultimate design wind speeds, Vult, and shall
be converted in accordance with Section 1609.3.1 to nominal
design wind speeds, Vasd, when the provisions of the
standards referenced in Exceptions 4 and 5 are used.- Subject to the limitation s of Section 1609.1.1.1, the provisions of ICC 600 shall be permitted for applicable Group R-2 and R-3 buildings.
- Subject to the limitations of Section 1609.1.1.1, residential structures using the provisions of AWC 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 TIA-222 for antenna-supporting structures and antennas, provided the horizontal extent of Topographic Category 2 escarpments in Section 2.6.6.2 of TIA-222 shall be 16 times the height of the escarpment.
- Wind tunnel tests in accordance with ASCE 49 and Sections 31.4 and 31.5 of ASCE 7.
- Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
- Linear interpolation between contours is permitted.
- Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
- Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
- Wind speeds correspond to approximately a 7% probability of exceedance in 50 years (Annual Exceedance Probability = 0.00143, MRI= 700 Years).
ULTIMATE DESIGN WIND SPEEDS, vult, FOR RISK CATEGORY II BUILDINGS AND OTHER STRUCTURES
- Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
- Linear interpolation between contours is permitted.
- Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
- Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
- Wind speeds correspond to approximately a 3% probability of exceedance in 50 years (Annual Exceedance Probability= 0.000588, MRI= 1700 Years).
ULTIMATE DESIGN WIND SPEEDS, vult, FOR RISK CATEGORY I BUILDINGS AND OTHER STRUCTURES
- Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for Exposure C category.
- Linear interpolation between contours is permitted.
- Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
- Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
- Wind speeds correspond to approximately a 15% probability of exceedance in 50 years (Annual Exceedance Probability= 0.00333, MRI= 300 Years).
ULTIMATE DESIGN WIND SPEEDS, vult, FOR RISK CATEGORY I BUILDINGS AND OTHER STRUCTURES
The provisions of ICC 600
are applicable only to buildings located within Exposure
B or C as defined in Section 1609.4. The provisions
of ICC 600, A WC WFCM and AISI S230 shall
not apply to buildings sited on the upper half of an isolated
hill, ridge or escarpment meeting the following
conditions:
- The hill, ridge or escarpment is 60 feet (18288 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.
In wind-borne debris
regions, glazing in buildings shall be impact resistant or
protected with an impact-resistant covering meeting the
requirements of an approved impact-resistant standard or
ASTM E1996 and ASTM E1886 referenced herein as follows:
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.
- Glazed openings located within 30 feet (9144 mm) of grade shall meet the requirements of the large missile test of ASTM E1996.
- Glazed openings located more than 30 feet (9144 mm) above grade shall meet the provisions of the small missile test of ASTM E1996.
Exceptions:
- 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 buildings with a mean roof height of 33 feet (10058 mm) or less that are classified as a Group R-3 or R-4 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 corrosion-resistant attachment hardware provided and anchors permanently installed on the building. Attachment in accordance with Table 1609.1.2 with corrosion- resistant attachment hardware provided and anchors permanently installed on the building is permitted for buildings with a mean roof height of 45 feet (13716 mm) or less where Vasd determined in accordance with Section 1609.3.1 does not exceed 140 mph (63 m/s).
- Glazing in Risk Category I buildings, 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 Risk Category II, III or IV buildings located over 60 feet (18288 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.
| FASTENER TYPE | FASTENER SPACING (inches) | ||
|---|---|---|---|
| Panel Span ≤ 4 feet |
4 feet < Pane Span ≤ 6 feet |
6 feet < Panel Span ≤ 8 feet |
|
| No. 8 wood-screw-based anchor with 2-inch embedment length | 16 | 10 | 8 |
| No. 10 wood-screw-based anchor with 2-inch embedment length | 16 | 12 | 9 |
| 1/4-inch diameter lag-screw-based anchor with 2-inch embedment length | 16 | 16 | 16 |
- This table is based on 140 mph wind speeds and a 45-foot 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 vibration-resistant anchors having a minimum ultimate withdrawal capacity of 1,500 pounds.
Louvers protecting intake and
exhaust ventilation ducts not assumed to be open that
are located within 30 feet (9144 mm) of grade shall
meet the requirements of AMCA 540.
The text of
Section 6.2.2 of ASTM E1996 shall be substituted as
follows:
6.2.2 Unless otherwise specified, select the wind
zone based on the strength design wind speed, Vult,
as follows:
6.2.2.1 Wind Zone 1-130 mph ≤ ultimate design wind speed, vult < 140 mph.
6.2.2.2 Wind Zone 2-140 mph ≤ ultimate design wind speed, Vult < 150 mph at greater than one mile (1.6 km) from the coastline. The coastline shall be measured from the mean high water mark.
6.2.2.3 Wind Zone 3-150 mph (58 m/s) ≤ ultimate design wind speed, Vult ≤ 160 mph (63 m/s), or 140 mph (54 m/s) ≤ ultimate design wind speed, Vult ≤ 160 mph (63 m/s) and within one mile (1.6 km) of the coastline. The coastline shall be measured from the mean high water mark.
6.2.2.4 Wind Zone 4- ultimate design wind speed, vult >160 mph (63 m/s).
6.2.2.1 Wind Zone 1-130 mph ≤ ultimate design wind speed, vult < 140 mph.
6.2.2.2 Wind Zone 2-140 mph ≤ ultimate design wind speed, Vult < 150 mph at greater than one mile (1.6 km) from the coastline. The coastline shall be measured from the mean high water mark.
6.2.2.3 Wind Zone 3-150 mph (58 m/s) ≤ ultimate design wind speed, Vult ≤ 160 mph (63 m/s), or 140 mph (54 m/s) ≤ ultimate design wind speed, Vult ≤ 160 mph (63 m/s) and within one mile (1.6 km) of the coastline. The coastline shall be measured from the mean high water mark.
6.2.2.4 Wind Zone 4- ultimate design wind speed, vult >160 mph (63 m/s).
Garage door glazed opening
protection for wind-borne debris shall meet the requirements
of an approved impact-resisting standard or
ANSI/DASMA 115.
For the purposes of Section 1609 and as
used elsewhere in this code, the following terms are defined
in Chapter 2.
HURRICANE-PRONE REGIONS.
WIND-BORNE DEBRIS REGION.
WIND SPEED, vult.
WIND SPEED, Vasd.
HURRICANE-PRONE REGIONS.
WIND-BORNE DEBRIS REGION.
WIND SPEED, vult.
WIND SPEED, Vasd.
The ultimate design
wind speed, vult, in mph, for the determination of the wind
loads shall be determined by Figures 1609.3(1), 1609.3(2)
and 1609.3(3). The ultimate design wind speed, v.1, for use in
the design of Risk Category II buildings and structures shall
be obtained from Figure 1609.3(1). The ultimate design wind
speed, vult, for use in the design of Risk Category III and IV
buildings and structures shall be obtained from Figure
1609.3(2). The ultimate design wind speed, vult, for use in the
design of Risk Category I buildings and structures shall be
obtained from Figure 1609.3(3). The ultimate design wind
speed, Vult, for the special wind regions indicated near mountainous
terrain and near gorges shall be in accordance with
local jurisdiction requirements. The ultimate design wind
speeds, vult, determined by the local jurisdiction shall be in
accordance with Section 26.5.1 of ASCE 7.
In nonhurricane-prone regions, when the ultimate design wind speed, Vult, is estimated from regional climatic data, the ultimate design wind speed, Vult, shall be determined in accordance with Section 26.5.3 of ASCE 7.
In nonhurricane-prone regions, when the ultimate design wind speed, Vult, is estimated from regional climatic data, the ultimate design wind speed, Vult, shall be determined in accordance with Section 26.5.3 of ASCE 7.
When required, the
ultimate design wind speeds of Figures 1609.3(1),
1609.3(2) and 1609.3(3) shall be converted to nominal
design wind speeds, Vasd, using Table 1609.3.1 or Equation
16-33.
(Equation 16-33)
For SI: 1 mile per hour = 0.44 m/s.
(Equation 16-33)
| where: |
||
| Vasd | = | Nominal design wind speed applicable to methods specified in Exceptions 4 and 5 of Section 1609.1.1. |
| Vult | = | Ultimate design wind speeds determined from Figures 1609.3(1), 1609.3(2) or 1609.3(3). |
| Vult | 100 |
110 | 120 | 130 | 140 | 150 | 160 | 170 | 180 | 190 | 200 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Vasd |
78 | 85 | 93 | 101 | 108 | 116 | 124 | 132 | 139 | 147 | 155 |
- Linear interpolation is permitted.
- Vasd = nominal design wind speed applicable to methods specified in Exceptions I through 5 of Section 1609. 1. 1.
- Vult =ultimate design wind speeds determined from Figure 1609.3(1), 1609.3(2) or 1609.3(3).
For each wind direction considered,
an exposure category that adequately reflects the characteristics
of ground surface irregularities shall be determined
for the site at which the building or structure is to be constructed.
Account shall be taken of variations in ground surface
roughness that arise from natural topography and
vegetation as well as from constructed features.
For each selected
wind direction at which the wind loads are to be evaluated,
the exposure of the building or structure shall be determined
for the two upwind sectors extending 45 degrees
(0.79 rad) either side of the selected wind direction. The
exposures in these two sectors shall be determined in
accordance with Sections 1609.4.2 and 1609.4.3 and the
exposure resulting in the highest wind loads shall be used
to represent winds from that direction.
A ground surface
roughness within each 45-degree (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 single-family
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, and grasslands.
Surface Roughness D. Flat, unobstructed areas and water surfaces. This category includes smooth mud flats, salt flats and unbroken ice.
Surface Roughness C. Open terrain with scattered obstructions having heights generally less than 30 feet (9144 mm). This category includes flat open country, and grasslands.
Surface Roughness D. Flat, unobstructed areas and water surfaces. This category includes smooth mud flats, salt flats and unbroken ice.
An exposure category
shall be determined in accordance with the following:
Exposure B. For buildings with a mean roof height of
less than or equal to 30 feet (9144 mm), Exposure B
shall apply where the ground surface roughness, as
defined by Surface Roughness B, prevails in the
upwind direction for a distance of at least 1,500 feet
(457 m). For buildings with a mean roof height greater
than 30 feet (9144 mm), Exposure B shall apply where
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.
Exposure C. Exposure C shall apply for all cases where Exposure B or D does 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 also apply where the ground surface roughness immediately upwind of the site is B or C, and the site is within a distance of 600 feet (183 m) or 20 times the building height, whichever is greater, from an Exposure D condition as defined in the previous sentence.
Exposure C. Exposure C shall apply for all cases where Exposure B or D does 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 also apply where the ground surface roughness immediately upwind of the site is B or C, and the site is within a distance of 600 feet (183 m) or 20 times the building height, whichever is greater, from an Exposure D condition as defined in the previous sentence.
The roof deck shall be designed to
withstand the wind pressures determined in accordance
with ASCE 7.
Roof coverings shall comply
with Section 1609.5.1.
Asphalt shingles installed over a roof deck complying with Section 1609.5.1 shall comply with the wind-resistance requirements of Section 1504.1.1.
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 wind-resistance requirements of Section 1504.1.1.
Wind loads on rigid tile roof coverings
shall be determined in accordance with the following
equation:
Concrete and clay roof tiles complying with the following limitations shall be designed to withstand the aerodynamic uplift moment as determined by this section.
Ma = qhCLbLLa [1.0 - GCP]
(Equation 16-34)
For SI:
| where: | ||
| b | = | Exposed width, feet (mm) of the roof tile. |
| CL | = | Lift coefficient. The lift coefficient for concrete and clay tile shall be 0.2 or shall be determined by test in accordance with Section 1504.2.1. |
| GCp | = | Roof pressure coefficient for each applicable roof zone determined from Chapter 30 of ASCE 7. Roof coefficients shall not be adjusted for internal pressure. |
| L |
= | Length, feet (mm) of the roof tile. |
| La | = | 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. |
| Ma | = | Aerodynamic uplift moment, feet-pounds (N-mm) acting to raise the tail of the tile. |
| qh | = | Wind velocity pressure, psf (kN/m2) determined from Section 27.3.2 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 that 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 two-thirds of the tile's area free of mortar or adhesive contact.
The alternate wind
design provisions in this section are simplifications of the
ASCE 7 Directional Procedure.
As an alternative to ASCE 7 Chapters 27
and 30, the following provisions are permitted to be used
to determine the wind effects on regularly shaped buildings,
or other structures that are regularly shaped, that
meet all of the following conditions:
- The building or other structure is less than or equal to 75 feet (22860 mm) in height with a height-to-least-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 26.2, where wind loads are only transmitted to the main windforce-resisting 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.
The following modifications
shall be made to certain subsections in ASCE 7: in
Section 1609.6.2, symbols and notations that are specific
to this section are used in conjunction with the
symbols and notations in ASCE 7 Section 26.3.
Coefficients and variables
used in the alternative all-heights method equations
are as follows:
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929m2, 1 degree = 0.0175 rad.
| Cnet | = | Net-pressure coefficient based on Kd [(G) (Cp)- (GCPi)], in accordance with Table 1609.6.2. |
| G | = | Gust effect factor for rigid structures in accordance with ASCE 7 Section 26.9.1. |
| Kd | = | Wind directionality factor in accordance with ASCE 7 Table 26-6. |
| Pnet | = | Design wind pressure to be used in determination of wind loads on buildings or other structures or their components and cladding, in psf (kN/m2). |
| STRUCTURE OR PART THEREOF |
DESCRIPTION | CnetFACTOR | ||||
|---|---|---|---|---|---|---|
| 1. Main windforce- resisting frames and systems |
Walls: | Enclosed | Partially enclosed | |||
| + Internal pressure |
- Internal pressure |
+ Internal pressure |
- Internal pressure |
|||
| 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 | ||
| Parapet wall | Windward | 1.28 | 1.28 | |||
| Leeward | -0.85 | -0.85 | ||||
| Roofs: | Enclosed | Partially enclosed | ||||
| Wind perpendicular to ridge | + Internal pressure |
- Internal pressure |
+ Internal pressure |
- Internal pressure |
||
| 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 | |||
| 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) | ||||||
| Flat< Slope < 6:12 (27°) See ASCE 7 Figure 30.4-2B 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 30.4-2A 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 30.4-2C 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 | ||||
| Flat < Slope < 7:12 (30°) See ASCE 7 Figure 30.4-5B Zone 1 | ||||||
| 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 flat-topped roofs h > 60 feet | Enclosed | Partially enclosed | ||||
| Flat< Slope< 2:12 (10°) (Zone 1) See ASCE 7 Figure 30.8-1 Zone 1 |
||||||
| Negative | 10 square feet or less | -1.34 | -1.66 | |||
| 500 square feet or more | -0.92 | -1.23 | ||||
| 3. Components and cladding in areas of discontinuity-roofs and overhangs |
Gable or hipped configurations at ridges, eaves and rakes (Zone 2) | |||||
| Flat< Slope< 6:12 (27°) See ASCE 7 Figure 30.4-2B 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 30.4-2B 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 30.4-2C |
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 30.4-2C 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) | ||||||
| Flat < Slope< 7:12 (30 °) See ASCE 7 Figure 30.4-58 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 feet | Enclosed | Partially enclosed | ||||
| Flat < Slope < 2: 12 (10°) (Zone 2) See ASCE 7 Figure 30.8-1 Zone 2 | ||||||
| Negative | 10 square feet or less | -2.11 | -2.42 | |||
| 100 square feet or more | -1.51 | -1.83 | ||||
| Gable or hipped configurations at comers (Zone 3) See ASCE 7 Figure 30.4-2B 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 | ||||
| Overhang for Slope Flat < Slope < 6:12 (27°) See ASCE 7 Figure 30.4-2B 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 30.4-2C 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 30.4-5B 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 feet | Enclosed | Partially enclosed | ||||
| Flat < Slope < 2 :12 (10°) (Zone 3) See ASCE 7 Figure 30.8-1 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 |
Wall Elements: h ≤ 60 feet (Zone 4) ASCE 7 Figure 30.4-1 | 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 | -1.09 | -1.40 | |||
| 500 square feet or more | -0.83 | -1.15 | ||||
| Wall Elements : h > 60 feet (Zone 4) See ASCE 7 Figure 30.6-1 Zone 4 | ||||||
| Positive | 20 square feet or less | 0.92 | 1.23 | |||
| 500 square feet or more | 066 | 0.98 | ||||
| Negative | 20 square feet or less | -0.92 | -1.23 | |||
| 500 square feet or more | -0.75 |
-1.06 | ||||
| Parapet Walls | ||||||
| Positive | 2.87 | 3.19 | ||||
| Negative | -1.68 | -2.00 | ||||
| 5. Components and cladding in areas of dicontinuity-walls and parapets |
Wall elements: h ≤ 60 feet (Zone 5) ASCE 7 Figure 30.4-1 | 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 feet (Zone 5) See ASCE 7 Figure 30.6-1 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 | ||||
| Parapet walls | ||||||
| Positive | 3.64 | 3.95 | ||||
| Negative | -2.45 | -2.76 | ||||
- Linear interpolation between values in the table is permitted.
- Some Cnet values have been grouped together. Less conservative results may be obtained by applying ASCE 7 provisions.
When using the alternative
all-heights 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 16-35.
Design wind forces for the MWFRS shall be not less than 16 psf (0.77 kN/m2) multiplied by the area of the structure projected on a plane normal to the assumed wind direction (see ASCE 7 Section 27.4.7 for criteria). Design net wind pressure for components and cladding shall be not less than 16 psf (0.77 kN/m2) acting in either direction normal to the surface.
Pnet = 0.00256V2KzCnetKzt
(Equation 16-35)
Design wind forces for the MWFRS shall be not less than 16 psf (0.77 kN/m2) multiplied by the area of the structure projected on a plane normal to the assumed wind direction (see ASCE 7 Section 27.4.7 for criteria). Design net wind pressure for components and cladding shall be not less than 16 psf (0.77 kN/m2) acting in either direction normal to the surface.
The MWFRS and the components
and cladding of every building or other structure
shall be designed for the pressures calculated using Equation
16-35.
The
MWFRS shall be investigated for the torsional effects
identified in ASCE 7 Figure 27.4-8.
Velocity pressure
exposure coefficient, Kz, shall be determined in
accordance with ASCE 7 Section 27.3.1 and the topographic
factor, Kzt, shall be determined in accordance
with ASCE 7 Section 26.8.
- For the windward side of a structure, Kzt and Kz shall be based on height z.
- For leeward and sidewalls, and for windward and leeward roofs, Kzt and Kz shall be based on mean roof height h.
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, Cnet.
- The pressure coefficient, Cnet, for walls and roofs shall be determined from Table 1609.6.2.
- Where Cnet, has more than one value, the more severe wind load condition shall be used for design.
When
using the alternative all-heights method, wind pressures
shall be applied simultaneously on, and in a direction
normal to, all building envelope wall and roof surfaces.
Wind
pressure for each component or cladding element is
applied as follows using Cnet 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 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 (Zone 2 or 3) shall be combined with design pressures that apply specifically on rakes or eave overhangs.
Foundation walls and retaining walls shall
be designed to resist lateral soil loads. Soil loads specified in
Table 1610.1 shall be used as the minimum design lateral soil
loads unless determined otherwise by a geotechnical investigation
in accordance with Section 1803. Foundation walls
and other walls in which horizontal movement is restricted at
the top shall be designed for at-rest pressure. Retaining walls
free to move and rotate at the top shall be permitted to be
designed for active pressure. Design lateral pressure from
surcharge loads shall be added to the lateral earth pressure
load. Design lateral pressure shall be increased if soils at the
site are expansive. Foundation walls shall be designed to support
the weight of the full hydrostatic pressure of undrained
backfill unless a drainage system is installed in accordance
with Sections 1805.4.2 and 1805.4.3.
For SI: 1 pound per square foot per foot of depth = 0.157 kPa/m, 1 foot = 304.8 mm.
Exception: Foundation walls extending not more than 8
feet (2438 mm) below grade and laterally supported at the
top by flexible diaphragms shall be permitted to be
designed for active pressure.
| DESCRIPTION OF BACKFILL MATERIALc | UNIFIED SOIL CLASSIFICATION |
DESIGN LATERAL SOIL LOADa (pound per square foot per foot of depth) |
|
|---|---|---|---|
| Active pressure | At-rest pressure | ||
| Well-graded, clean gravels; gravel-sand mixes | GW | 30 | 60 |
| Poorly graded clean gravels; gravel-sand mixes | GP | 30 | 60 |
| Silty gravels, poorly graded gravel-sand mixes | GM | 40 | 60 |
| Clayey gravels, poorly graded gravel-and-clay mixes | GC | 45 | 60 |
| Well-graded, clean sands; gravelly sand mixes | SW | 30 | 60 |
| Poorly graded clean sands; sand-gravel mixes | SP | 30 | 60 |
| Silty sands, poorly graded sand-silt mixes | SM | 45 | 60 |
| Sand-silt clay mix with plastic fines | SM-SC | 45 | 100 |
| Clayey sands, poorly graded sand-clay mixes | SC | 60 | 100 |
| Inorganic silts and clayey silts | ML | 45 | 100 |
| Mixture of inorganic silt and clay | ML-CL | 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 |
| Organic clays and silty clays | OH | Note b | Note b |
- 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 material s shall be in accordance with ASTM D2487.
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 100-year
hourly rainfall rate indicated in Figure 1611.1 or on other
rainfall rates determined from approved local weather data.
[P] FIGURE 1611.1
100-YEAR, 1-HOUR 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
100-YEAR, 1-HOUR 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
100-YEAR, 1-HOUR 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
100-YEAR, 1-HOUR 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
100-YEAR, 1-HOUR RAINFALL (INCHES) HAWAII
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
R = 5.2(ds + dh)
(Equation 16-36)
For SI: R = 0.0098(ds + dh)
| where: | ||
| dh | = | 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). |
| ds | = | 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/m2). 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. |
100-YEAR, 1-HOUR RAINFALL (INCHES) WESTERN UNITED STATES
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
100-YEAR, 1-HOUR RAINFALL (INCHES) CENTRAL UNITED STATES
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
100-YEAR, 1-HOUR RAINFALL (INCHES) EASTERN UNITED STATES
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
100-YEAR, 1-HOUR RAINFALL (INCHES) ALASKA
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
100-YEAR, 1-HOUR RAINFALL (INCHES) HAWAII
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington, DC.
Susceptible bays of roofs shall
be evaluated for ponding instability in accordance with Section
8.4 of ASCE 7.
Roofs equipped with hardware
to control the rate of drainage shall be equipped with a secondary
drainage system at a higher elevation that limits accumulation
of water on the roof above that elevation. Such roofs
shall be designed to sustain the load of rainwater that will
accumulate on them to the elevation of the secondary drainage
system plus the uniform load caused by water that rises
above the inlet of the secondary drainage system at its design
flow determined from Section 1611.1. Such roofs shall also
be checked for ponding instability in accordance with Section
1611.2.
Within flood hazard areas as established in
Section 1612.3, all new construction of buildings, structures
and portions of buildings and structures, including substantial
improvement and restoration of substantial damage to buildings
and structures, shall be designed and constructed to resist
the effects of flood hazards and flood loads. For buildings
that are located in more than one flood hazard area, the provisions
associated with the most restrictive flood hazard area
shall apply.
The following terms are defined in Chapter
2:
BASE FLOOD.
BASE FLOOD ELEVATION.
BASEMENT.
COASTAL A ZONE.
COASTAL HIGH HAZARD AREA.
DESIGN FLOOD.
DESIGN FLOOD ELEV A TION.
DRY FLOODPROOFING.
EXISTING STRUCTURE.
FLOOD or FLOODING.
FLOOD DAMAGE-RESISTANT MATERIALS.
FLOOD HAZARD AREA.
FLOOD INSURANCE RATE MAP (FIRM).
FLOOD INSURANCE STUDY.
FLOODWAY.
LOWEST FLOOR.
SPECIAL FLOOD HAZARD AREA.
START OF CONSTRUCTION.
SUBSTANTIAL DAMAGE.
SUBSTANTIAL IMPROVEMENT.
BASE FLOOD.
BASE FLOOD ELEVATION.
BASEMENT.
COASTAL A ZONE.
COASTAL HIGH HAZARD AREA.
DESIGN FLOOD.
DESIGN FLOOD ELEV A TION.
DRY FLOODPROOFING.
EXISTING STRUCTURE.
FLOOD or FLOODING.
FLOOD DAMAGE-RESISTANT MATERIALS.
FLOOD HAZARD AREA.
FLOOD INSURANCE RATE MAP (FIRM).
FLOOD INSURANCE STUDY.
FLOODWAY.
LOWEST FLOOR.
SPECIAL FLOOD HAZARD AREA.
START OF CONSTRUCTION.
SUBSTANTIAL DAMAGE.
SUBSTANTIAL IMPROVEMENT.
To establish
flood hazard areas, the applicable governing authority shall
adopt a flood hazard map and supporting data. The flood hazard
map shall include, at a minimum, areas of special flood
hazard as identified by the Federal Emergency Management
Agency in an engineering report entitled "The Flood Insurance
Study for [INSERT NAME OF JURISDICTION]," dated
[INSERT DATE OF ISSUANCE], as amended or revised with the
accompanying Flood Insurance Rate Map (FIRM) and Flood
Boundary and Floodway Map (FBFM) and related supporting
data along with any revisions thereto. The adopted flood hazard
map and supporting data are hereby adopted by reference
and declared to be part of this section.
Absent the
adoption of a flood hazard map and supporting data, flood
hazard areas as determined by the state under its administration
of the Part 31, floodplain regulatory authority of
the natural resources and environmental protection act,
1994 PA 451, MCL 324.101 to 324.90106, shall become
the basis for regulation of floodplain development within
the community and section 1612 shall apply to buildings
and structures within those areas.
R 408.30451c
R 408.30451c
In riverine flood
hazard areas where design flood elevations are specified
but floodways have not been designated, the applicant
shall provide a floodway analysis that demonstrates that
the proposed work will not increase the design flood elevation
more than 1 foot (305 mm) at any point within the
jurisdiction of the applicable governing authority.
The design and construction
of buildings and structures located in flood hazard areas,
including coastal high hazard areas and coastal A zones,
shall be in accordance with Chapter 5 of ASCE 7 and ASCE
24.
All of the following are in addition to the
requirements of ASCE 24:
- Buildings and structures in flood hazard areas subject to high velocity wave action (zone V) shall be in compliance with the requirements of ASCE 24 for such flood hazard areas.
- The lowest floors of structure category II buildings and structures shall be at or above the elevation specified in ASCE 24 or 1 foot (305 mm) above the design flood elevation, whichever is higher.
- The lowest floors of structure category III and IV buildings and structures in flood hazard areas not subject to high velocity wave action (zone A) shall be at or above the elevation specified in ASCE 24 or 1 foot (305 mm) above the 500-year flood elevation, whichever is higher. For the purpose of this requirement, the 500-year flood elevation is the elevation of flooding having a 0.2% chance of being equaled or exceeded in any given year.
- Dry floodproofing for structure category II buildings and structures shall extend to or above the elevation specified in ASCE 24 or 1 foot (305 mm) above the design flood elevation, whichever is higher.
- Dry floodproofing for structure category III and IV buildings and structures shall extend to or above the elevation specified in ASCE 24 or 1 foot (305 mm) above the 500-year flood elevation, whichever is higher. For the purpose of this requirement, the 500 -year flood elevation is the elevation of flooding having a 0.2% chance of being equaled or exceeded in any given year.
- The interior floor or finished ground level of under-floor spaces and crawlspaces shall comply with section 1805.1.2.1 of this code.
The following documentation shall be prepared and sealed by a registered design
professional and submitted to the building official:
- For construction in flood hazard areas other than
coastal high hazard areas or coastal A zones:
- The elevation of the lowest floor, including the basement, as required by the lowest floor elevation inspection in Section 110.3.3 and for the final inspection in Section 110.3.10.1.
- 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 2.7.2.1 of ASCE 24, construction documents sub item three shall include a statement that the design will provide for equalization of hydrostatic flood forces in accordance with Section 2.7.2.2 of ASCE 24.
- For dry floodproofed nonresidential buildings, construction documents shall include a statement that the dry floodproofing is designed in accordance with ASCE 24.
- For construction in coastal high hazard areas and
coastal A zones:
- The elevation of the bottom of the lowest horizontal structural member as required by the lowest floor elevation inspection in Section 110.3.3 and for the final inspection in Section 110.3.10.1.
- 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.
- For breakaway walls designed to have a resistance of more than 20 psf (0.96 kN/m2) determined using allowable stress design, 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 two-family dwellings, assigned to Seismic Design Category A, B or C, or located where the mapped short-period spectral response acceleration, Ss, is less than 0.4 g.
- The seismic force-resisting system of wood-frame 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 terms are defined in Chapter
2:
DESIGN EARTHQUAKE GROUND MOTION.
ORTHOGONAL.
RISK-TARGETED MAXIMUM CONSIDERED
EARTHQUAKE (MCER) GROUND MOTION
RESPONSE ACCELERATION.
SEISMIC DESIGN CATEGORY.
SEISMIC FORCE-RESISTING SYSTEM.
SITE CLASS.
SITE COEFFICIENTS.
DESIGN EARTHQUAKE GROUND MOTION.
ORTHOGONAL.
RISK-TARGETED MAXIMUM CONSIDERED
EARTHQUAKE (MCER) GROUND MOTION
RESPONSE ACCELERATION.
SEISMIC DESIGN CATEGORY.
SEISMIC FORCE-RESISTING SYSTEM.
SITE CLASS.
SITE COEFFICIENTS.
Seismic ground
motion values shall be determined in accordance with this
section.
The parameters
Ss and S1 shall be determined from the 0.2 and 1-second
spectral response accelerations shown on Figures
1613.3.1(1) through 1613.3.1(8). Where S1 is less than or
equal to 0.04 and Ss is less than or equal to 0.15, the structure
is permitted to be assigned Seismic Design Category A.
FIGURE 1613.3.1(1)
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR THE CONTERMINOUS UNITED STATES OF 0.2-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.3.1(2)
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR THE CONTERMINOUS UNITED STATES OF 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
0.2 Second Spectral Response Acceleration (5% of Critical Damping)
1.0 Second Spectral Response Acceleration (5% of Critical Damping)
FIGURE 1613.3.1(3)
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR HAWAII OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.3.1(4)
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR ALASKA OF 0.2-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.3.1(5)
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR ALASKA OF 1.0-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
0.2 Second Spectral Response Acceleration (5% of Critical Damping)
1.0 Second Spectral Response Acceleration (5% of Critical Damping)
FIGURE 1613.3.1(6)
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS
FOR PUERTO RICO AND THE UNITED STATES VIRGIN ISLANDS OF 0.2-AND 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.3.1(7)
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS
FOR GUAM AND THE NORTHERN MARIANA ISLANDS OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
FIGURE 1613.3.1(8)
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS FOR
AMERICAN SAMOA OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR THE CONTERMINOUS UNITED STATES OF 0.2-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR THE CONTERMINOUS UNITED STATES OF 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR HAWAII OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR ALASKA OF 0.2-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE
ACCELERATIONS FOR ALASKA OF 1.0-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS
FOR PUERTO RICO AND THE UNITED STATES VIRGIN ISLANDS OF 0.2-AND 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS
FOR GUAM AND THE NORTHERN MARIANA ISLANDS OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS FOR
AMERICAN SAMOA OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION
(5% OF CRITICAL DAMPING), SITE CLASS B
Based on the site soil
properties, the site shall be classified as Site Class A, B, C,
D, E or Fin accordance with Chapter 20 of ASCE 7.
Where 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 Site Class E or F soils are present at the site.
Where 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 Site Class E or F soils are present at the site.
The maximum considered earthquake spectral
response acceleration for short periods, SMS, and at 1-
second period, SM1, adjusted for site class effects shall be
determined by Equations 16-37 and 16-38, respectively:
SMS = FaSs
(Equation 16-37)
SM1 = FvS1
(Equation 16-38)
| where: | ||
| Fa | = | Site coefficient defined in Table 1613.3.3(1). |
| Fv | = | Site coefficient defined in Table 1613.3.3(2). |
| Ss | = | The mapped spectral accelerations for short periods as determined in Section 1613.3.1. |
| S1 | = | The mapped spectral accelerations for a 1-second period as determined in Section 1613.3.1. |
| SITE CLASS |
MAPPED SPECTRAL RESPONSE ACCELERATION AT SHORT PERIOD | ||||
|---|---|---|---|---|---|
| Ss ≤ 0.25 | Ss = 0.50 | Ss = 0.75 | Ss = 1.00 | Ss ≥ 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 straight-line interpolation for intermediate values of mapped spectral response acceleration at short period, Ss.
- Values shall be determined in accordance with Section 11.4.7 of ASCE 7.
| SITE CLASS |
MAPPED SPECTRAL RESPONSE ACCELERATION AT 1-SECOND PERIOD | ||||
|---|---|---|---|---|---|
| S1 ≤ 0.1 | S1 = 0.2 | S1 = 0.3 | S1 = 0.4 | S1 ≥ 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 straight-line interpolation for intermediate values of mapped spectral response acceleration at 1-second period, Ss.
- Values shall be determined in accordance with Section 11.4.7 of ASCE 7.
Five-percent damped design spectral response acceleration
at short periods, SDs, and at 1-second period, SD1
shall be determined from Equations 16-39 and 16-40,
respectively:
(Equation 16-39)
(Equation 16-40)
(Equation 16-39)
(Equation 16-40)
| where: | ||
| SMS | = | The maximum considered earthquake spectral response accelerations for short period as determined in Section 1613.3.3. |
| SM1 | = | The maximum considered earthquake spectral response accelerations for 1-second period as determined in Section 1613.3.3. |
Structures classified as Risk Category I, II or III that are
located where the mapped spectral response acceleration
parameter at 1-second period, S1, is greater than or equal to
0.75 shall be assigned to Seismic Design Category F.
Structures classified as Risk Category IV that are located
where the mapped spectral response acceleration parameter
at 1-second period, S1, 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 risk category and the design spectral
response acceleration parameters, SDS and SD1, determined
in accordance with Section 1613.3.4 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 1613.3.5(1) or 1613.3.5(2), irrespective
of the fundamental period of vibration of the
structure, T.
| VALUE OF SDS | RISK CATEGORY | ||
|---|---|---|---|
| I or II | Ill | IV | |
| SDS < 0.167g | A |
A | A |
| 0.167g ≤ SDS< 0.33g | B | B | C |
| 0.33g ≤ SDS < 0.50g | C | C | D |
| 0.50g ≤ SDS | D | D | D |
| VALUE OF SD1 | RISK CATEGORY | ||
|---|---|---|---|
| I or II | Ill | IV | |
| SD1 < 0.067g | A |
A | A |
| 0.067g: ≤ SD1< 0.133g | B | B | C |
| 0.133g ≤ SD1 < 0.20g | C | C | D |
| 0.20g ≤ SD1 | D | D | D |
Where S1 is less than 0.75, the seismic
design category is permitted to be determined from
Table 1613.3.5(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 Ts 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 Ts
- Equation 12.8-2 of ASCE 7 is used to determine the seismic response coefficient, Cs.
- The diaphragms are rigid or are permitted to be idealized as rigid in accordance with Section 12.3.1 of ASCE 7 or, for diaphragms permitted to be idealized as flexible in accordance with Section 12.3.1 of ASCE 7, the distances between vertical elements of the seismic force-resisting system do not exceed 40 feet (12192 mm).
Where the
alternate simplified design procedure of ASCE 7 is
used, the seismic design category shall be determined
in accordance with ASCE 7.
The provisions of Section
1613.4 shall be permitted as alternatives to the relevant provisions
of ASCE 7.
Add the following exception
to the end of Section 17.5.4.2 of ASCE 7:
Exception: For isolated structures designed in accordance
with this standard, the structural system limitations
including structural height limits, in Table 12.2-1
for ordinary steel concentrically braced frames (OCBFs)
as defined in Chapter 11 and ordinary moment frames
(OMFs) as defined in Chapter 11 are permitted to be
taken as 160 feet (48768 mm) for structures assigned to
Seismic Design Category D, E or F, provided that the
following conditions are satisfied:
- The value of R, as defined in Chapter 17 is taken as 1.
- For OMFs and OCBFs, design is in accordance with AISC 341
The provisions of Section
1613.5 shall be permitted as an amendment to the relevant
provisions of ASCE 7.
Modify ASCE 7 Section 12.11.2.2.1 as follows:
12.11.2.2.1 Transfer of anchorage forces into diaphragm.
Diaphragms shall be provided with continuous
ties or struts between diaphragm chords to distribute
these anchorage forces into the diaphragms. Diaphragm
connections shall be positive, mechanical or welded.
Added chords are permitted to be used to form subdiaphragms
to transmit the anchorage forces to the main
continuous cross-ties. The maximum length-to-width
ratio of a wood, wood structural panel or untopped steel
deck sheathed structural subdiaphragm that serves as
part of the continuous tie system shall be 2.5 to 1. Connections
and anchorages capable of resisting the prescribed
forces shall be provided between the diaphragm
and the attached components. Connections shall extend
into the diaphragm a sufficient distance to develop the
force transferred into the diaphragm.
Ballasted,
roof-mounted photovoltaic panel systems need not be rigidly
attached to the roof or supporting structure. Ballasted nonpenetrating
systems shall be designed and installed only on
roofs with slopes not more than one unit vertical in 12 units
horizontal. Ballasted nonpenetrating systems shall be
designed to resist sliding and uplift resulting from lateral and
vertical forces as required by Section 1605, using a coefficient
of friction determined by acceptable engineering principles.
In structures assigned to Seismic Design Category C, D,
E or F, ballasted nonpenetrating systems shall be designed to
accommodate seismic displacement determined by nonlinear
response-history analysis or shake-table testing, using input
motions consistent with ASCE 7 lateral and vertical seismic
forces for nonstructural components on roofs.
Ice-sensitive structures shall be designed for
atmospheric ice loads in accordance with Chapter 10 of
ASCE 7.
Ice-sensitive structures shall be designed for
atmospheric ice loads in accordance with Chapter 10 of
ASCE 7.
Buildings with an occupied floor 75 feet (22860 mm) or more in height above the lowest level of fire
department vehicle access and assigned to risk category III or IV shall comply with the requirements of this section. Frame
structures shall comply with the requirements of section
1615.3. Bearing wall structures shall comply with the requirements
of section 1615.4.
R 408.30428
R 408.30428
Frame structures shall comply
with the requirements of this section.
Frame structures
constructed primarily of reinforced or prestressed concrete,
either cast-in-place or precast, or a combination of
these, shall conform to the requirements of Section 4.10 of
ACI 318. 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 two-thirds of the required
one-way 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 reinforcement
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 one-third of the required one-way 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.
Frame structures constructed with a structural steel
frame or a frame composed of open web steel joists, joist
girders with or without other structural steel elements or a
frame composed of composite steel or composite steel
joists and reinforced concrete elements shall conform to
the requirements of this section.
Each column splice shall have
the minimum design strength in tension to transfer the
design dead and live load tributary to the column between the splice and the splice or base immediately
below.
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 two-thirds 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 -inch-diameter (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
one-third of the required shear strength for LRFD,
but not less than 10 kips (45 kN).
Bearing wall structures
shall have vertical ties in all load-bearing walls and longitudinal
ties, transverse ties and perimeter ties at each floor level
in accordance with this section and as shown in Figure
1615.4.
FIGURE 1615.4
LONGITUDINAL, PERIMETER, TRANSVERSE AND VERTICAL TIES
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 load-bearing
walls and shall connect to exterior load-bearing walls
and shall be spaced at not greater than 10 feet (3038
mm) on center. Ties shall have a minimum nominal
tensile strength, TT, given by Equation 16-41. 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.
TT = w LS ≤ αT S
(Equation 16-41)
| 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/m2). |
| S | = | The spacing between ties, feet (m). |
| αT | = | 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 cold-formed steel light-frame construction. |
Transverse 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. Transverse
ties shall be placed no farther apart than the spacing of
load-bearing walls. Transverse ties shall have minimum
nominal tensile strength TT given by Equation 16-41.
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.
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 TP, given by
Equation 16-42. 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.
For SI: TP = 90.7w ≤ βT
TP = 200w ≤ βT
(Equation 16-42)
For SI: TP = 90.7w ≤ βT
| where: |
||
| w | = | As defined in Section 1615.4.2.1. |
| βT | = | 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 cold-formed steel light-frame construction. |
Vertical ties shall consist of
continuous or spliced reinforcing, continuous or spliced
members, wall sheathing or other engineered systems.
Vertical tension ties shall be provided in bearing walls
and shall be continuous over the height of the building.
The minimum nominal tensile strength for vertical ties
within a bearing wall shall be equal to the weight of the
wall within that story plus the weight of the diaphragm
tributary to the wall in the story below. No fewer than
two ties shall be provided for each wall. The strength of
each tie need not exceed 3,000 pounds per foot (450
kN/m) of wall tributary to the tie for walls of masonry
construction or 750 pounds per foot (140 kN/m) of wall
tributary to the tie for walls of cold-formed steel light-frame
construction.
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