ICC Subscriptions
 
SECTION 1615A MODIFICATIONS TO ASCE 7

1615A.1 General.
The text of ASCE 7 shall be modified as indicated in Sections 1615A.1.1 through 1615A.1.41.

1615A.1.1 ASCE 7,
Section 11.1. Modify ASCE 7 Section 11.1 by the adding Section 11.1.5 as follows:

11.1.5 Structural design criteria. Where design reviews are required in ASCE 7, Chapters 16, 17 or 18, the ground motion, analysis, and design methods, material assumptions and acceptance criteria proposed by the engineer shall be submitted to the enforcement agency in the form of structural design criteria for approval.


[OSHPD 1 & 4] Peer review requirements in Section 3414A shall apply to design reviews required by ASCE 7 Chapters 17 and 18.


1615A.1.2A [DSA-SS] ASCE 7, Section 11.4.7.
Modify ASCE 7 Section 11.4.7 as follows:

11.4.7 Site-specific ground motion procedures.
The site-specific ground motion procedure set forth in ASCE 7 Section 21 as modified in Section 1803A.6 of this code is permitted to be used to determine ground motion for any structure.

Unless otherwise approved, the site-specific procedure per ASCE 7 Section 21 as modified by Section 1803A.6 of this code shall be used where any of the following conditions apply:


1) A site response analysis shall be performed per Section 21.1, and a ground motion hazard analysis shall be performed in accordance with Section 21.2 for the following structures:


a) Structure located in Type E soils and mapped MCE spectral acceleration at short periods (Ss) exceeds 2.0g.


b) Structures located in Type F soils.


Exceptions:


1) Where Ss is less than 0.20g, use of Type E soil profile shall be permitted.


2) Where exception to Section 20.3.1 is applicable except for base isolated buildings.


2) A ground motion hazard analysis shall be performed in accordance with Section 21.2 when:


a) A time history response analysis of the building is performed as part of the design.


b) The building site is located in an area identified in Section 4-317(e) of the California Administrative Code (Part 1, Title 24, C.C.R).


c) For seismically isolated structures and for structures with damping systems.


1615A.1.2B. [OSHPD 1 & 4]
Modify ASCE 7 Section 11.4.7 by adding the following:

For buildings assigned to Seismic Design Category F, or when required by the building official, a ground motion hazard analysis shall be performed in accordance with ASCE 7 Chapter 21 as modified by Section 1803A.6.


1615A.1.3 ASCE 7, Table 12.2-1.
Modify ASCE 7 Table 12.2-1 as follows:

A. BEARING WALL SYSTEMS


5. Intermediate Precast Shear Walls—Not permitted by OSHPD.


14. Light-framed walls with shear panels of all other materials—Not permitted by OSHPD and DSA-SS.


B. BUILDING FRAME SYSTEMS


2. Steel eccentrically braced frames, non-moment-resisting connections at columns away from links—Not permitted by OSHPD.


4. Ordinary steel concentrically braced frames—Not permitted by OSHPD.


9. Intermediate Precast Shear Walls—Not permitted by OSHPD.


24. Light-framed walls with shear panels of all other materials—Not permitted by OSHPD and DSA-SS.


25. Buckling-restrained braced frames, non-moment-resisting beam-column connections—Not permitted by OSHPD.


27. Special steel plate shear wall—Not permitted by OSHPD.


C. MOMENT-RESISTING FRAME SYSTEMS


2. Special steel truss moment frames—Not permitted by OSHPD.


3. Intermediate steel moment frames—Not permitted by OSHPD.


4. Ordinary steel moment frames—Not permitted by OSHPD.


Exceptions:


1. Systems listed in this section can be used as an alternative system when preapproved by the enforcement agency.


2. Rooftop or other supported structures not exceeding two stories in height and 10 percent of the total structure weight can use the systems in this section when designed as components per ASCE 7 Chapter 13.


3. Systems listed in this section can be used for seismically isolated buildings when permitted by Section 1613A.6.2.


1615A.1.4 ASCE 7, Section 12.2.3.1.
Modify ASCE 7 Section 12.2.3.1 by adding the following additional requirements for a two stage equivalent lateral force procedure or modal response spectrum procedure:

e. Where design of elements of the upper portion is governed by special seismic load combinations, the special loads shall be considered in the design of the lower portion.


1615A.1.5 ASCE 7, Section 12.3.3.
Modify first sentence of ASCE 7 Section 12.3.3.1 as follows:

12.3.3.1 Prohibited horizontal and vertical irregularities for Seismic Design Categories D through F. Structures assigned to Seismic Design Category D, E or F having horizontal structural irregularity Type 1b of Table 12.3-1 or vertical structural irregularities Type 1b, 5a or 5b of Table 12.3-2 shall not be permitted.


1615A.1.6 ASCE 7, Section 12.7.2.
Modify ASCE 7 Section 12.7.2 by adding Item 5 to read as follows:

5. Where buildings provide lateral support for walls retaining earth, and the exterior grades on opposite sides of the building differ by more than 6 feet (1829 mm), the load combination of the seismic increment of earth pressure due to earthquake acting on the higher side, as determined by a geotechnical engineer qualified in soils engineering plus the difference in earth pressures shall be added to the lateral forces provided in this section.


1615A.1.7 ASCE 7, Section 12.8.7.
Modify ASCE 7 Section 12.8.7 by replacing Equation 12.8-16 as follows:



(12.8-16)

1615A.1.8 ASCE 7, Section 12.9.4.
Replace ASCE 7 Section 12.9.4 as follows:

12.9.4 Scaling design values of combined response. Modal base shear shall not be less than the base shear calculated using the equivalent lateral force procedure of Section 12.8.


1615A.1.9 ASCE 7, Section 12.10.2.1.
Modify ASCE 7 Section 12.10.2.1 by adding the following:

The value of
Ω0QE used in load combinations with overstrength factors in ASCE 7-05 Section 12.4.3.2 for design of collector elements, splices and their connections to resisting elements may be taken as the largest of the following:

1)
Ω0Fx (where Fx is given by ASCE 7-05 Eq.12.8-11)

2)
Ω0Fpx (where Fpx is given by ASCE 7-05 Eq. 12.10-1 ignoring the 0.2SDSIwpx minimum)

3) 0.2SDSIwpx (Minimum value from Section 12.10.1.1)


1615A.1.10 ASCE 7, Section 12.13.1.
Modify ASCE 7 Section 12.13.1 by adding Section 12.13.1.1 as follows:

12.13.1.1 Foundations and superstructure-to-foundation connections.
The foundation shall be capable of transmitting the design base shear and the overturning forces from the structure into the supporting soil. Stability against overturning and sliding shall be in accordance with Section 1605A.1.1.

In addition, the foundation and the connection of the superstructure elements to the foundation shall have the strength to resist, in addition to gravity loads, the lesser of the following seismic loads:


1. The strength of the superstructure elements.


2. The maximum forces that would occur in the fully yielded structural system.


3. Forces from the Load Combinations with overstrength factor in accordance with ASCE 7 Section 12.4.3.2.


Exceptions:


1. Where referenced standards specify the use of higher design loads.


2. When it can be demonstrated that inelastic deformation of the foundation and superstructure-to-foundation connection will not result in a weak story or cause collapse of the structure.


3. Where basic structural system consists of light framed walls with shear panels.


Where the computation of the seismic overturning moment is by the equivalent lateral-force method or the modal analysis method, reduction in overturning moment permitted by section 12.13.4 of ASCE 7 may be used.


Where moment resistance is assumed at the base of the superstructure elements, the rotation and flexural deformation of the foundation as well as deformation of the superstructure-to-foundation connection shall be considered in the drift and deformation compatibility analyses.


1615A.1.11 ASCE 7, Section 13.1.3. [OSHPD 1 & 4]
Modify ASCE 7 Section 13.1.3 by the following:

For position retention, the design of supports and attachments for all nonstructural components shall have a component importance factor, Ip, equal to 1.5.


1615A.1.12 ASCE 7, Section 13.1.4.
Replace ASCE 7 Section 13.1.4 with the following:

13.1.4 Exemptions.
The following nonstructural components are exempt from the requirements of this section:

1. Furniture (except storage cabinets as noted in Table 13.5-1).


2. Temporary or moveable equipment.


Exceptions:


a) Equipment shall be anchored if it is permanently attached to the building utility services such as electricity, gas or water.
For the purposes of this requirement, "permanently attached" shall include all electrical connections except three- prong plugs for duplex receptacles.

b) The enforcement agency shall be permitted to require temporary attachments for movable equipment which is usually stationed in one place and heavier than 400 pounds, when they are not in use for a period longer than 8 hours at a time.


3. Architectural, mechanical and electrical components in Seismic Design Categories D, E or F where all of the following apply:


a. The component is positively attached to the structure;


b. Flexible connections are provided between the component and associated ductwork, piping and conduit; and either:


i. The component weighs 400 pounds (1780 N) or less and has a center of mass located 4 feet (1.22 m) or less above the adjacent floor or roof level that directly support the component;


Exception:
Special Certification Requirements for Designated Seismic Systems in accordance with Section 13.2.2 shall apply.

or


ii. The component weighs 20 pounds (89 N) or less or, in the case of a distributed system, 5 lb/ft (73 N/m) or less.


Exception:
The enforcement agency shall be permitted to require attachments for equipment with hazardous contents to be shown on construction documents irrespective of weight.

1615A.1.13 ASCE 7, Section 13.3.2.
Modify ASCE 7 Section 13.3.2 by adding the following:

The seismic relative displacements to be used in design of displacement sensitive nonstructural components is D
p I instead of Dp, where Dp is given by Equations 13.3-5 to 13.3-8 and I is the building importance factor given in Section 11.5.

1615A.1.14 ASCE 7, Section 13.4
Replace ASCE 7 Sections 13.4.1 and 13.4.2 with the following:

13.4.1 Design force in the attachment.
The force in the attachment shall be determined based on the prescribed forces and displacements for the component as determined in Sections 13.3.1 and 13.3.2 except that Rp shall not be taken as larger than 6.

13.4.2 Anchors in concrete or masonry.


13.4.2.1 Anchors in concrete.
Anchors in concrete used for component anchorage shall be designed in accordance with Appendix D of ACI 318.

13.4.2.2 Anchors in masonry.
Anchors in masonry used for component anchorage shall be designed in accordance with ACI 530. Anchors shall be designed to be governed by the tensile or shear strength of a ductile steel element.

Exception:
Anchors shall be permitted to be designed so that the attachment that the anchor is connecting to the structure undergoes ductile yielding at a load level corresponding to anchor forces not greater than their design strength, or the minimum design strength of the anchors shall be at least 2.5 times the factored forces transmitted by the attachment.

13.4.2.3 Postinstalled anchors in concrete and masonry.
Postinstalled anchors shall fulfill the requirements of Section 13.4.2.1 or 13.4.2.2. Postinstalled anchors in concrete used for component anchorage shall be pre-qualified for seismic applications in accordance with ACI 355.2, ICC-ES AC193 or ICC-ES AC308. Postinstalled anchors in masonry used for component anchorage shall be prequalified for seismic applications in accordance with ICC-ES AC01, AC58 or AC106.

Exceptions:


1) Adhesive anchors shall not be permitted in overhead applications or application with sustained (continuous) tension load that can lead to creep.


2) Anchors pre-qualified for seismic applications need not be governed by the steel strength of a ductile steel element.


1615A.1.15 ASCE 7, Section 13.4.5.
Replace ASCE 7 Section 13.4.5 with the following:

13.4.5 Power actuated fasteners.
Power actuated fasteners in concrete or steel shall not be used for sustained tension loads or for brace applications in Seismic Design Categories D, E, or F unless approved for seismic loading. Power actuated fasteners in masonry shall not be permitted unless approved for seismic loading.

Exception:
Power actuated fasteners in concrete used for support of acoustical tile or lay-in panel suspended ceiling applications and distributed systems where the service load on any individual fastener does not exceed 90 lb (400 N). Power actuated fasteners in steel where the service load on any individual fastener does not exceed 250 lb (1,112 N).

1615A.1.16 ASCE 7, Section 13.5.6.
Replace ASCE 7, Section 13.5.6 with the following:

13.5.6 Suspended ceilings.
Suspended ceilings shall be in accordance with this section.

13.5.6.1 Seismic forces.
The weight of the ceiling, Wp, shall include the ceiling grid; ceiling tiles or panels; light fixtures if attached to, clipped to, or laterally supported by the ceiling grid; and other components that are laterally supported by the ceiling. Wp shall be taken as not less than 4 psf (19 N/m2).

The seismic force, F
p, shall be transmitted through the ceiling attachments to the building structural elements or the ceiling-structure boundary.


13.5.6.2 Seismic design requirements.
Suspended acoustical tile or lay-in panel ceilings shall be designed in accordance with ASTM E 580 Section 5.2.8.8 and the requirements of Sections 13.5.6.2.1 and 13.5.6.2.2, or be designed in accordance with Section 13.2.1.1, or be seismically qualified in accordance with Sections 13.2.5 or 13.2.6.

13.5.6.2.1 Industry standard construction for acoustical tile or lay-in panel ceilings.
Acoustical tile or lay-in panel ceilings in Seismic Design Categories D, E, and F shall be designed and installed in accordance with ASTM C 635, ASTM C 636, and ASTM E 580, Section 5 - Seismic Design Categories D, E, and F as modified by Section 13.5.6.2.2.

13.5.6.2.2 Modification to ASTM E 580.
Modify ASTM E 580 by the following:

1. Exitways. Lay-in ceiling assemblies in exitways of hospitals and essential services buildings shall be installed with a main runner or cross runner surrounding all sides of each piece of tile, board or panel and each light fixture or grille. A cross runner that supports another cross runner shall be considered as a main runner for the purpose of structural classification. Splices or intersections of such runners shall be attached with through connectors such as pop rivets, screws, pins, plates with end tabs or other approved connectors.


2. Corridors and Lobbies. Expansion joints shall be provided in the ceiling at intersections of corridors and at junctions of corridors and lobbies or other similar areas.


3. Lay-in panels. Metal panels and panels weighing more than 1/
2 pounds per square foot (24 N/m2) other than acoustical tiles shall be positively attached to the ceiling suspension runners.

4. Lateral force bracing.
Lateral force bracing is required for all ceiling areas except that they shall be permitted to be omitted in rooms with floor areas up to 144 square feet when perimeter support in accordance with ASTM E 580 Sections 5.2.2 and 5.2.3 are provided and perimeter walls are designed to carry the ceiling lateral forces.

5.
Ceiling fixtures. Fixtures installed in acoustical tile or lay-in panel ceilings shall be mounted in a manner that will not compromise ceiling performance.

All recessed or drop-in light fixtures and grilles shall be supported directly from the fixture housing to the structure above with a minimum of two 12 gage wires located at diagonally opposite corners. Leveling and positioning of fixtures may be provided by the ceiling grid. Fixture support wires may be slightly loose to allow the fixture to seat in the grid system. Fixtures shall not be supported from main runners or cross runners if the weight of the fixtures causes the total dead load to exceed the deflection capability of the ceiling suspension system.


Fixtures shall not be installed so that the main runners or cross runners will be eccentrically loaded.


Surface-mounted fixtures shall be attached to the main runner with at least two positive clamping devices made of material with a minimum of 14 gage. Rotational spring catches do not comply. A 12 gage suspension wire shall be attached to each clamping device and to the structure above.


6.
Partitions. Where the suspended ceiling system is required to provide lateral support for the permanent or relocatable partitions, the connection of the partition to the ceiling system, the ceiling system members and their connections, and the lateral force bracing shall be designed to support the reaction force of the partition from prescribed loads applied perpendicular to the face of the partition. Partition connectors, the suspended ceiling system and the lateral-force bracing shall all be engineered to suit the individual partition application and shall be shown or defined in the drawings or specifications.

1615A.1.17 ASCE 7, Section 13.5.7. [OSHPD 1 & 4]
Modify ASCE 7 Section 13.5.7 by the following:

All access floors shall be special access floors in accordance with Section 13.5.7.2.


1615A.1.18
Reserved.

1615A.1.19
Reserved.

1615A.1.20 ASCE 7, Section 13.6.5.
Modify ASCE 7, Section 13.6.5 by deleting Item 6 in Section 13.6.5.5 and adding Section 13.6.5.6 as follows:

13.6.5.6 Conduit, Cable Tray, and Other Electrical Distribution Systems (Raceways).
Raceways shall be designed for seismic forces and seismic relative displacements as required in Section 13.3. Conduit greater than 2.5 inches (64 mm) trade size and attached to panels, cabinets or other equipment subject to seismic relative displacement of Section 13.3.2 shall be provided with flexible connections or designed for seismic forces and seismic relative displacements as required in Section 13.3.

Exceptions:


1. Design for the seismic forces and relative displacements of Section 13.3 shall not be required for raceways where either:


a.
Trapeze assemblies are used to support raceways and the total weight of the raceway supported by trapeze assemblies is less than 10 lb/ft (146 N/m), or

b.
The raceway is supported by hangers and each hanger in the raceway run is 12 in. (305 mm) or less in length from the raceway support point to the supporting structure. Where rod hangers are used with a diameter greater than 3/8 inch, they shall be equipped with swivels to prevent inelastic bending in the rod.

2. Design for the seismic forces and relative displacements of Section 13.3 shall not be required for conduit, regardless of the value of I
p, where the conduit is less than 2.5 in. (64 mm) trade size.


1615A.1.21 ASCE 7, Section 13.6.7.
Replace ASCE 7, Section 13.6.7 with the following:

13.6.7 Ductwork.
HVAC and other ductwork shall be designed for seismic forces and seismic relative displacements as required in Section 13.3. Ductwork designed to carry toxic, highly toxic, or explosive gases, or used for smoke control shall be designed and braced without considering the Exceptions noted below.

Exceptions:


The following exceptions pertain to ductwork not designed to carry toxic, highly toxic, or flammable gases or used for smoke control:


1. Design for the seismic forces and relative displacements of Section 13.3 shall not be required for ductwork where either:


a.
Trapeze assemblies are used to support ductwork and the total weight of the ductwork supported by trapeze assemblies is less than 10 lb/ft (146 N/m); or

b.
The ductwork is supported by hangers and each hanger in the duct run is 12 in. (305 mm) or less in length from the duct support point to the supporting structure. Where rod hangers are used with a diameter greater than 3/8 inch, they shall be equipped with swivels to prevent inelastic bending in the rod.

2. Design for the seismic forces and relative displacements of Section 13.3 shall not be required where provisions are made to avoid impact with larger ducts or mechanical components or to protect the ducts in the event of such impact; and HVAC ducts have a cross-sectional area of 6 ft
2 (0.557 m2) or less, or weigh 10 lb/ft (146 N/m) or less.

HVAC duct systems fabricated and installed in accordance with standards approved by the authority having jurisdiction shall be deemed to meet the lateral bracing requirements of this section.


Components that are installed in-line with the duct system and have an operating weight greater than 75 lb (334 N), such as fans, heat exchangers and humidifiers, shall be supported and laterally braced independent of the duct system and such braces shall meet the force requirements of Section 13.3.1. Appurtenances such as dampers, louvers and diffusers shall be positively attached with mechanical fasteners. Unbraced piping attached to in-line equipment shall be provided with adequate flexibility to accommodate the seismic relative displacements of Section 13.3.2.


1615A.1.22 ASCE 7, Section 13.6.8.
Replace ASCE 7, Section 13.6.8 with the following:

13.6.8 Piping Systems.
Unless otherwise noted in this section, piping systems shall be designed for the seismic forces and seismic relative displacements of Section 13.3. ASME pressure piping systems shall satisfy the requirements of Section 13.6.8.1. Fire protection sprinkler piping shall satisfy the requirements of Section 13.6.8.2. Elevator system piping shall satisfy the requirements of Section 13.6.10.

Where other applicable material standards or recognized design bases are not used, piping design including consideration of service loads shall be based on the following allowable stresses:


a. For piping constructed with ductile materials (e.g., steel, aluminum, or copper), 90 percent of the minimum specified yield strength.


b. For threaded connections in piping constructed with ductile materials, 70 percent of the minimum specified yield strength.


c. For piping constructed with nonductile materials (e.g., cast iron, or ceramics), 10 percent of the material minimum specified tensile strength.


d.
For threaded connections in piping constructed with nonductile materials, 8 percent of the material minimum specified tensile strength.

Piping not detailed to accommodate the seismic relative displacements at connections to other components shall be provided with connections having sufficient flexibility to avoid failure of the connection between the components.


13.6.8.1 ASME Pressure Piping Systems.
Pressure piping systems, including their supports, designed and constructed in accordance with ASME B 31 shall be deemed to meet the force, displacement, and other requirements of this section. In lieu of specific force and displacement requirements provided in ASME B 31, the force and displacement requirements of Sections 13.3 shall be used.

13.6.8.2 Fire protection sprinkler piping systems.
Fire protection sprinkler piping designed and constructed in accordance with NFPA 13 shall be deemed to meet the force and displacement requirements of this section. The exceptions of Section 13.6.8.3 shall not apply.

Exception:
Pipe hangers, bracing, and anchor capacities shall be determined in accordance with material chapters of the California Building Code, in lieu of using those in NFPA 13. The force and displacement requirements of Section 13.3 or those in the NFPA 13 may be used for design.

13.6.8.3 Exceptions.
Design of piping systems and attachments for the seismic forces and relative displacements of Section 13.3 shall not be required where one of the following conditions apply:

1. Trapeze assemblies are used to support piping whereby no single pipe exceeds the limits set forth in 3a. or b. below and the total weight of the piping supported by the trapeze assemblies is less than 10 lb/ft (146 N/m).


2.
The piping is supported by hangers and each hanger in the piping run is 12 in. (305 mm) or less in length from the top of the pipe to the supporting structure. Where pipes are supported on a trapeze, the trapeze shall be supported by hangers having a length of 12 in. (305 mm) or less. Where rod hangers are used with a diameter greater than 3/8 inch, they shall be equipped with swivels, eye nuts or other devices to prevent bending in the rod.

3. Piping having an R
p in Table 13.6-1 of 4.5 or greater is used and provisions are made to avoid impact with other structural or nonstructural components or to protect the piping in the event of such impact and where the following size requirements are satisfied:

a. For Seismic Design Categories D, E or F and values of I
p greater than one, the nominal pipe size shall be 1 inch (25 mm) or less.

b.
For Seismic Design Categories D, E or F, where Ip = 1.0 the nominal pipe size shall be 3 inches (80 mm) or less.

The exceptions above shall not apply to elevator piping.


13.6.8.4 Other Piping Systems.
Piping not designed and constructed in accordance with ASME B 31 or NFPA 13 shall comply with the requirements of Section 13.6.11.

1615A.1.23
ASCE 7, Section 13.6.10.1. Modify ASCE 7 Section 13.6.10.1 by adding Section 13.6.10.1.1 as follows:

13.6.10.1.1 Elevators guide rail support.
The design of guide rail support-bracket fastenings and the supporting structural framing shall use the weight of the counterweight or maximum weight of the car plus not less than 40 percent of its rated load. The seismic forces shall be assumed to be distributed one third to the top guiding members and two thirds to the bottom guiding members of cars and counterweights, unless other substantiating data are provided. In addition to the requirements of ASCE 7 Section 13.6.10.1, the minimum seismic forces shall be 0.5g acting in any horizontal direction.

1615A.1.24 ASCE 7, Section 13.6.10.4.
Replace ASCE 7 Section 13.6.10.4 as follows:

13.6.10.4 Retainer plates. Retainer plates are required at the top and bottom of the car and counterweight, except where safety devices acceptable to the enforcement agency are provided which meet all requirements of the retainer plates, including full engagement of the machined portion of the rail. The design of the car, cab stabilizers, counterweight guide rails and counterweight frames for seismic forces shall be based on the following requirements:


1. The seismic force shall be computed per the requirements of ASCE 7 Section 13.6.10.1. The minimum horizontal acceleration shall be 0.5g for all buildings.


2. W
p shall equal the weight of the counterweight or the maximum weight of the car plus not less than 40 percent of its rated load.

3. With the car or counterweight located in the most adverse position, the stress in the rail shall not exceed the limitations specified in these regulations, nor shall the deflection of the rail relative to its supports exceed the deflection listed below:


RAIL SIZE
(weight per foot
of length,
pounds)
WIDTH OF
MACHINED
SURFACE
(inches)
ALLOWABLE
RAIL
DEFLECTION
(inches)
8
11/4
0.20
11
11/2
0.30
12
13/4
0.40
15
131/32
0.50
181/2
131/32
0.50
221/2
2
0.50
30
21/4
0.50


For SI: 1 inch = 25 mm, 1 foot = 305 mm, 1 pound = 0.454 kg.

Note:
Deflection limitations are given to maintain a consistent factor of safety against disengagement of retainer plates from the guide rails during an earthquake.


4. Where guide rails are continuous over supports and rail joints are within 2 feet (610 mm) of their supporting brackets, a simple span may be assumed.


5. The use of spreader brackets is allowed.


6. Cab stabilizers and counterweight frames shall be designed to withstand computed lateral load with a minimum horizontal acceleration of 0.5g.


1615A.1.25 ASCE 7, Section 16.1.3.2.
Modify ASCE 7 Section 16.1.3.2 by the following:

Where next generation attenuation relations are used in accordance with Section 1803A.6.2, each pair of motions shall be scaled such that in the period range from 0.2T to 1.5T, the average of the SRSS spectra from all horizontal component pairs does not fall below the corresponding ordinate of the design response spectrum determined using NGA relations.


At sites within 3.1 miles (5 km) of an active fault that controls the hazard, each pair of components shall be rotated to the fault-normal and fault-parallel direction of the causative fault, and shall be scaled so that average of the fault-normal components is not less than the Maximum Considered Earthquake (MCE) response spectrum determined using NGA relations for each period range from 0.2T to 1.5T.


1615A.1.26 ASCE 7, Section 16.1.4.
Modify ASCE 7 Section 16.1.4 by the following:

For each ground motion analyzed, the individual response parameters shall be multiplied by the following scalar quantities:


a. Force response parameters shall be multiplied by I/R, where I is the importance factor determined in accordance with Section 11.5.1, and R is the response modification coefficient selected in accordance with Section 12.2.1.


b. Drift quantities shall be multiplied by Cd/R, where Cd is the deflection amplification factor specified in Table 12.2-1.


The distribution of horizontal shear shall be in accordance with Section 12.8.4.


1615A.1.27 ASCE 7, Section 16.2.2.
Modify ASCE 7 Section 16.2.2 by adding the following:

Requirements of this section shall be deemed to be satisfied for new buildings, using acceptance criteria, in Section 16.2.4.2 by the nonlinear modeling parameters in ASCE 41.


1615A.1.28 ASCE 7, Section 16.2.3.
Modify ASCE 7 Section 16.2.3 by adding the following:

Requirements of this section shall be deemed to be satisfied by using load combinations in Sections 12.4.2.3 and 12.4.3.2 with 25 percent of the required live loads.


1615A.1.29 ASCE 7, Section 16.2.4.
Modify ASCE 7 Section 16.2.4 by the following:

a) Where site is located within 3.1 miles (5 km) of an active fault at least seven ground motions shall be analyzed and response parameters shall be based on larger of the average of the maximum response with ground motions applied as follows:


1. Each of the ground motions shall have their maximum component at the fundamental period aligned in one direction.


2. Each of the ground motion’s maximum component shall be rotated orthogonal to the previous analysis direction.


b) Where site is located more than 3.1 miles (5 km) from an active fault at least 10 ground motions shall be analyzed. The ground motions shall be applied such that one-half shall have their maximum component aligned in one direction and the other half aligned in the orthogonal direction. The average of the maximum response of all the analyses shall be used for design.


1615A.1.30 ASCE 7, Section 16.2.4.1.
Replace ASCE 7 exception to Section 16.2.3 by the following:

Where this standard requires the consideration of the load combinations with overstrength factor of Section 12.4.3.2, average demand from MCE analysis obtained from suite of analysis in accordance with Section 16.2.4 shall be used with Immediate Occupancy (IO) acceptance criteria in Section 16.2.4.2.


1615A.1.31 ASCE 7, Section 16.2.4.2 [OSHPD 1 & 4]
Modify ASCE 7 Section 16.2.4.2 by the following:

Acceptance criteria for elements subjected to deformation beyond their linear range of response shall be based on ASCE 41 for Immediate Occupancy (IO) at Design Earthquake (DE) and Life Safety (LS) at Maximum Considered Earthquake (MCE). For LS acceptance criteria at MCE, primary components shall be within the acceptance criteria for primary components and secondary components shall be within the acceptance criteria for secondary components.


1615A.1.32 ASCE 7, Section 17.2.1.
Modify ASCE 7 Section 17.2.1 by adding the following:

The importance factor, Ip, for parts and portions of a seismically isolated building shall be the same as that required for a fixed-base building of the same occupancy category.


1615A.1.33 ASCE 7, Section 17.2.4.7.
Modify ASCE 7 Section 17.2.4.7 by adding the following:

The effects of uplift and/or rocking shall be explicitly accounted for in the analysis and in the testing of the isolator units.


1615A.1.34 ASCE 7, Section 17.2.5.2.
Modify ASCE 7, Section 17.2.5.2 by adding the following:

The separation requirements for the building above the isolation system and adjacent buildings shall be the sum of the factored displacements for each building. The factors to be used in determining separations shall be:


1. For seismically isolated buildings, the deformation resulting from the analyses using the maximum considered earthquake unmodified by RI.


2. For fixed based buildings, Cd times the elastic deformations resulting from an equivalent static analysis using the seismic base shear computed via ASCE 7 Section 12.8.


1615A.1.35 ASCE 7, Section 17.3.2.
Replace ASCE 7, Section 17.3.2 with the following:

17.3.2 Ground Motion Histories.
Where response history procedures are used, ground motions shall consist of pairs of appropriate horizontal ground motion acceleration components developed in accordance with Section 16.1.3.2 except that 0.2T and 1.5T shall be replaced by 0.5 TD and 1.25TM, respectively, where TD and TM are defined in Section 17.5.3.

1615A.1.36 ASCE 7, Section 17.4.
Modify ASCE 7, Section 17.4 by adding the following:

17.4.2.3 Linear procedures.
Linear procedures shall be limited to structures located at sites with S1 less than 0.6g.

1615A.1.37 ASCE 7, Section 17.6
Modify ASCE 7, Section 17.6 by the following:

17.6.1.1 Minimum seismic force.
For the response spectrum and linear response history procedures, Vb and Vs, shall not be taken less than those calculated in accordance with Equations 17.5-7 and 17.5-8.

1615A.1.38 ASCE 7, Section 18.3.1.
Modify ASCE 7, Section 18.3.1 by replacing the third paragraph with the following:

If the calculated force in an element of the seismic force resisting system does not exceed 1.5 times its nominal strength for the Maximum Considered Earthquake (MCE) nor its nominal strength for the design earthquake (DE), the element is permitted to be modeled as linear.


1615A.1.39 ASCE 7, Section 21.4.
Replace ASCE 7, Section 21.4 with the following:

21.4 Design Acceleration Parameters.
Where the site-specific procedure is used to determine the design ground motion in accordance with Section 21.3, the parameter SDS shall be taken as the spectral acceleration, Sa, obtained from the site-specific spectra at a period of 0.2 sec, except that it shall not be taken less than 90 percent of the peak spectral acceleration, Sa, at any period larger than 0.2 second. The parameter SD1 shall be taken as the greater of the spectral acceleration, Sa, at a period of 1 sec or two times the spectral acceleration, Sa, at a period of 2 sec.

For use with the equivalent lateral force procedure, the site specific spectral acceleration, Sa at T shall be permitted to replace SD1/T in Equation 12.8-3 and SD1TL/T2 in Equation 12.8-4. The parameter SDS calculated per this section shall be permitted to be used in Equations 12.8-2 and 12.8-5. The mapped value of S1 shall be used in Equation 12.8-6. The parameters SMS and SM1 shall be taken as 1.5 times SDS and SD1, respectively. The values so obtained shall not be less than 80 percent of the values determined in accordance with Section 11.4.3 for SMS and SM1 and Section 11.4.4 for SDS and SD1.


1615A.1.40 Earthquake Motion Measuring Instrumentation and Monitoring. [OSHPD 1 & 4]
Modify ASCE 7 by the following:

Scope:
For buildings with a seismic isolation system, a damping system or a lateral force resisting system (LFRS) not listed in ASCE 7 Table 12.2-1, earthquake motion measuring instrumentation and monitoring shall be required. Monitoring requirements shall also apply to welded steel moment frame buildings constructed under a permit issued prior to October 25, 1994.

Instrumentation:
There shall be a sufficient number of instruments to characterize the response of the building during an earthquake and shall include at least one tri-axial free field instrument or equivalent. A proposal for instrumentation and equipment specifications shall be forwarded to the enforcement agency for review and approval. The owner of the building shall be responsible for the implementation of the instrumentation program. Maintenance of the instrumentation and removal/ processing of the records shall be the responsibility of the enforcement agency.

Monitoring:
After every significant seismic events, where the ground shaking acceleration at the site exceeds 0.3g, or the acceleration at any monitored building level exceeds 0.8g, as measured by the seismic monitoring system in the building, the owner shall retain a structural engineer to make an inspection of the structural system. The inspection shall include viewing the performance of the building, reviewing the strong motion records, and a visual examination of the isolators, dampers and connections for deterioration, offset or physical damage. A report for each inspection, including conclusions on the continuing adequacy of the structural system, shall be submitted to the enforcement agency.

1615A.1.41 Operational Nonstructural Performance Level Requirements. [OSHPD 1 & 4]
New buildings designed and constructed to this code shall be deemed to satisfy operational nonstructural performance level when:

1. The facility has on-site supplies of water and holding tanks for wastewater, sufficient for 72 hours of emergency operations, which are integrated into the building plumbing systems. As an alternative, hook-ups to allow for the use of transportable sources of water and sanitary waste water disposal shall be permitted.


2. An on-site emergency system as defined within Part 3, Title 24 is incorporated into the building electrical system for critical care areas. Additionally, the system shall provide for radiological service and an onsite fuel supply for 72 hours of acute care operation.