Additional requirements for construction documents are included in Sections 4-210 and 4-317 of the California Administrative Code (Part 1, Title 24, C.C.R).
Connections that resist design seismic forces shall be designed and detailed on the design drawings.
Where unusual erection or construction procedures are considered essential by the project structural engineer or architect in order to accomplish the intent of the design or influence the construction, such procedure shall be indicated on the plans or in the specifications.
The maximum span-depth ratio for any roof or floor diaphragm consisting of steel and composite steel slab decking or concrete shall be based on test data and design calculations acceptable to the enforcement agency.
The deflection shall not exceed l/600 for veneered walls, anchored veneers and adhered veneers over 1 inch (25 mm) thick, including the mortar backing.
Risk Category IV includes structures as defined in the California Administrative Code, Section 4-207 and all structures required for their continuous operation or access/egress.
Structural analysis shall explicitly include consideration of stiffness of diaphragm in accordance with ASCE 7 Section 12.3.1. A diaphragm is rigid for the purpose of distribution of story shear and torsional moment where so indicated in Section 12.3.1 of ASCE 7.
For anchorage of concrete or masonry walls to roof and floor diaphragms, the out-of-plane strength design force shall not be less than 280 lb/linear ft (4.09 kN/m) of wall.
When checking stability under the provisions of Section 1605.1.1 using allowable stress design, the factor of safety for soil bearing values shall not be less than the overstrength factor of the structures supported.
The design dead load shall provide for the weight of at least one additional roof covering in addition to other applicable loadings if the new roof covering is permitted to be applied over the original roofing without its removal, in accordance with Section 1511.
The following minimum loads for stage accessories apply:
- Gridirons and fly galleries: 75 pounds per square foot uniform live load.
- Loft block wells: 250 pounds per lineal foot vertical load and lateral load.
- Head block wells and sheave beams: 250 pounds per lineal foot vertical load and lateral load. Head block wells and sheave beams shall be designed for all tributary loft block well loads. Sheave blocks shall be designed with a safety factor of five.
- Scenery beams where there is no gridiron: 300 pounds per lineal foot vertical load and lateral load.
- Ceiling framing over stages shall be designed for a uniform live load of 20 pounds per square foot. For members supporting a tributary area of 200 square feet or more, this additional load may be reduced to 15 pounds per square foot (0.72 kN/m2).
The minimum uniform live load for balconies and decks is 1.5 times the live load for the area served. Not required to exceed 100 psf.
The minimum uniform live load for a press box floor or accessible roof with railing is 100 psf.
The minimum vertical design live load shall be as follows:
12-inch-deep (305 mm) shelf - 33 pounds per lineal foot (482 N/m)
15-inch-deep (381 mm) shelf - 41 pounds per lineal foot (598 N/m), or 33 pounds per cubic foot (5183 N/m3) per total volume of the rack or cabinet, whichever is less.
18-inch-deep (457 mm) shelf - 100 pounds per lineal foot (1459 N/m), or
50 pounds per cubic foot (7853 N/m3) per total volume of the rack or cabinet, whichever is less.
20 pounds per cubic foot (311 N/m3) or 20 pounds per square foot (958 Pa), whichever is less, but not less than actual loads.
Uncovered open-frame roof structures shall be designed for a vertical live load of not less than 10 pounds per square foot (0.48 kN/m2) of the total area encompassed by the framework.
The ground snow load or the design snow load for roofs shall conform with the adopted ordinance of the city, county, or city and county in which the project site is located, and shall be approved by DSA.
The calculated story drift due to wind pressures with ultimate design wind speed, Vult, shall not exceed 0.008 times the story height for buildings less than 65 feet (19,812 mm) in height or 0.007 times the story height for buildings 65 feet (19,812 mm) or greater in height.
Exception: This story drift limit need not be applied for single-story open buildings in Risk Category I and II.
Flood hazard maps shall include, at a minimum, areas of special flood hazard as identified by the Federal Emergency Management Agency’s Flood Insurance Study (FIS) adopted by the local authority having jurisdiction where the project is located, 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 seismic design category for a structure shall be determined in accordance with Section 1613.
In addition to the definitions in Section 1613.2, the following words and terms shall, for the purposes of this section, have the meanings shown herein.
ACTIVE EARTHQUAKE FAULT. A fault that has been the source of earthquakes or is recognized as a potential source of earthquakes, including those that have exhibited surface displacement within Holocene time (about 11,000 years) as determined by California Geological Survey (CGS) under the Alquist-Priolo Earthquake Fault Zoning Act, those included as type A or type B faults for the U.S. Geological Survey (USGS) National Seismic Hazard Maps, and faults considered to have been active in Holocene time by an authoritative source, federal, state or local governmental agency.
DISTANCE FROM AN ACTIVE EARTHQUAKE FAULT. Distance measured from the nearest point of the building to the closest edge of an Alquist-Priolo Earthquake fault zone for an active fault, if such a map exists, or to the closest mapped splay of the fault.
IRREGULAR STRUCTURE. A structure designed as having one or more plan or vertical irregularities per ASCE 7 Section 12.3.
Seismic Design Category shall be determined in accordance with Section 1613.3.5.
Structures not assigned to Seismic Design Category E or F, in accordance with Section 1613.3, shall be assigned to Seismic Design Category D.
The alternative Seismic Design Category determination procedure of Section 16220.127.116.11 is not permitted by DSA-SS/CC.
The simplified design procedure of Section 1618.104.22.168 is not permitted by DSA-SS/CC.
Modify ASCE 7 Section 1.3 by adding Section 1.3.6 as follows:
1.3.6 Structural design criteria. Where design is based on ASCE 7 Chapters 16, 17, 18, or 31, the ground motion, wind tunnel design recommendations, analysis, and design methods, material assumptions, testing requirements, and acceptance criteria proposed by the engineer shall be submitted to the enforcement agency in the form of structural design criteria for approval.
Modify ASCE 7 Table 12.2-1 as follows:
- Light-framed walls with shear panels of all other materials - Not permitted by DSA-SS/CC.
- Light-framed walls with shear panels of all other materials - Not permitted by DSA-SS/CC.
- Systems listed in this section can be used as an alternative system when pre-approved by the enforcement agency.
- 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.
- Systems listed in this section can be used for seismically isolated buildings when permitted by Section 1613.4.1.
Replace ASCE 7 Section 22.214.171.124, Items 1 and 2 by the following:
The value of the response modification coefficient, R, used for design at any story shall not exceed the lowest value of R that is used in the same direction at any story above that story. Likewise, the deflection amplification factor, Cd, and the system over strength factor, Ωo, used for the design at any story shall not be less than the largest value of these factors that are used in the same direction at any story above that story.
Modify ASCE 7 Section 126.96.36.199 by adding the following additional requirements for a two stage equivalent lateral force procedure or modal response spectrum procedure:
f. 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 portions.
The exception in Item a is not permitted by DSA-SS/CC.
The exception in Item a is not permitted by DSA-SS/CC.
The exception in Item a is not permitted by DSA-SS/CC.
Modify ASCE 7 Section 188.8.131.52 as follows:
184.108.40.206 Prohibited horizontal and vertical irregularities for Seismic Design Categories D through F. Structures assigned to Seismic Design Category 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. Structures assigned to Seismic Design Category D having vertical irregularity Type 1b or 5b of Table 12.3-2 shall not be permitted.
Modify ASCE 7 Section 12.7.2 by adding Item 6 to read as follows:
6. 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.
Replace ASCE 7 Section 220.127.116.11 by the following:
18.104.22.168 Maximum SDS Value in Determination of Cs and Ev. The value of Cs and Ev are permitted to be calculated using a value of SDS equal to 1.0, but not less than 70% of SDS as defined in Section 11.4.4, provided that all of the following criteria are met:
- The structure does not have irregularities, as defined in Section 12.3.2;
- The structure does not exceed five stories above the base as defined in Section 11.2;
- The structure has a fundamental period, T, that does not exceed 0.5 seconds, as determined using Section 12.8.2;
- The structure meets the requirements necessary for the redundancy factor, ρ, to be permitted to be taken as 1.0, in accordance with Section 22.214.171.124;
- The site soil properties are not classified as Site Class E or F, as defined in Section 11.4.2; and
- The structure is classified as Risk Category I or II, as defined in Section 1.5.1.
Replace ASCE 7 Section 12.9.4 as follows:
12.9.4 Scaling design values of combined response. Modal base shears used to determine forces and drifts shall not be less than the base shear calculated using the equivalent lateral force procedure of Section 12.8.
Replace ASCE 7 Exception 1 of Section 126.96.36.199 by the following:
Exception: The forces calculated above need not exceed those calculated using the load combinations of Section 188.8.131.52 with seismic forces determined by Equation 12.10-3 and transfer forces, where applicable.
Modify ASCE 7 Section 12.13.1 by adding Section 184.108.40.206 as follows:
220.127.116.11 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 1605.1.1.
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:
- The strength of the superstructure elements.
- The maximum forces that can be delivered to the foundation in a fully yielded structural system.
- Where referenced standards specify the use of higher design loads.
- When it can be demonstrated that inelastic deformation of the foundation and super-structure-to-foundation connection will not result in a weak story or cause collapse of the structure.
- Where seismic force-resisting system consists of light-framed walls with shear panels, unless the reference standard specifies the use of higher design loads.
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.
Replace ASCE 7 Section 13.1.4 by the following:
13.1.4 Exemptions. The following nonstructural components are exempt from the requirements of this section:
- Furniture (except storage cabinets as noted in Table 13.5-1).
- 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 plugs for duplex receptacles.
- The enforcement agency shall be permitted to require temporary attachments for mov able equipment which is usually stationed in one place and heavier than 400 pounds or has a center of mass located 4 feet (1.22 m) or more above the adjacent floor or roof level that directly supports the component when they are not in use for a period longer than 8 hours at a time.
- The component is positively attached to the structure;
Replace ASCE 7, Section 13.5.6 by the following:
13.5.6 Suspended ceilings. Suspended ceilings shall be in accordance with this section.
18.104.22.168 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, Fp, shall be transmitted through the ceiling attachments to the building structural elements or the ceiling-structure boundary.
22.214.171.124 Industry standard construction for acoustical tile or lay-in panel ceilings. Unless designed in accordance with ASTM E580 Section 5.2.8, or seismically qualified in accordance with Sections 13.2.5 or 13.2.6, acoustical tile or lay-in panel ceilings shall be designed and constructed in accordance with this section.
126.96.36.199.1 Seismic Design Categories D through F. Acoustical tile or lay-in panel ceilings in Seismic Design Categories D, E and F shall be designed and installed in accordance with ASTM C635, ASTM C636, and ASTM E580, Section 5 - Seismic Design Categories D, E and F as modified by this section.
Exception to Section 188.8.131.52 shall not be used in accordance with ASTM E580 Section 5.5.
184.108.40.206.2 Modification to ASTM E580. Modify ASTM E580 by the following:
- 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. Lateral force diagonal bracing may be omitted in the short or transverse direction of exitways, not exceeding 8 feet wide, when perimeter support in accordance with ASTM E580 Sections 5.2.2 and 5.2.3 is provided and the perimeter wall laterally supporting the ceiling in the short or transverse direction is designed to carry the ceiling lateral forces. The connections between the ceiling grid, wall angle and the wall shall be designed to resist the ceiling lateral forces.
- 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.
- 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.
- 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 E580 Sections 5.2.2 and 5.2.3 are provided and perimeter walls are designed to carry the ceiling lateral forces. The connections between the ceiling grid, wall angle and the wall shall be designed to resist the ceiling lateral forces. Horizontal restraint point spacing shall be justified by analysis or test and shall not exceed a spacing of 12 feet by 12 feet. Bracing wires shall be secured with four tight twists in 11/2 inches, or an approved alternate connection.
- Ceiling support and bracing wires shall be spaced a minimum of 6” from all pipes, ducts, conduits and equipment that are not braced for horizontal forces, unless approved otherwise by the building official.
Modify ASCE 7, Section 220.127.116.11, Exceptions 1 and 2, as follows:
- 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
- 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, they shall be equipped with swivels to prevent inelastic bending in the rod.
- Design for the seismic forces of Section 13.3 shall not be required for conduit, regardless of the value of Ip, where the conduit is less than 2.5 in. (64 mm) trade size.
Replace ASCE 7, Section 13.6.7, Exceptions 1 and 2, by the following:
The following exceptions pertain to ductwork not designed to carry toxic, highly toxic or flammable gases, or used for smoke control:
- 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
- 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, they shall be equipped with swivels to prevent inelastic bending in the rod.
- Design for the seismic forces 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 ft2 (0.557 m2) or less, or weigh 10 lb/ft (146 N/m) or less.
Replace ASCE 7, Section 18.104.22.168 with the following:
22.214.171.124 Exceptions. Design of piping systems and attachments for the seismic forces of Section 13.3 shall not be required where one of the following conditions apply:
- 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).
- 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, they shall be equipped with swivels, eye nuts or other devices to prevent bending in the rod.
- For Seismic Design Categories D, E or F and values of Ip greater than one, the nominal pipe size shall be 1 inch (25 mm) or less.
- 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.
Modify ASCE 7 Section 126.96.36.199 by adding Section 188.8.131.52.1, as follows:
184.108.40.206.1 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 more 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 220.127.116.11, the minimum seismic forces shall be 0.5g acting in any horizontal direction.
Replace ASCE 7 Section 18.104.22.168, as follows:
22.214.171.124 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:
- The seismic force shall be computed per the requirements of ASCE 7 Section 126.96.36.199. The minimum horizontal acceleration shall be 0.5g for all buildings.
- Wp shall equal the weight of the counterweight or the maximum weight of the car plus not less than 40 percent of its rated load.
- 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 in Table 1224.4.11.
- 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.
- The use of spreader brackets is allowed.
- Cab stabilizers and counterweight frames shall be designed to withstand computed lateral load with a minimum horizontal acceleration of 0.5g.
Remove ASCE 7 Sections 188.8.131.52 and 184.108.40.206 and modify 16.1.4 by the following:
Maximum scaled base shears used to determine forces and drifts shall not be less than the base shear calculated using the equivalent lateral force procedure of Section 12.8.
Modify ASCE 7 Section 16.2.4 by the following:
- Each of the ground motions shall have their maximum component at the fundamental period aligned in one direction.
- Each of the ground motion’s maximum component shall be rotated orthogonal to the previous analysis direction.
- 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.
Modify ASCE 7 Section 220.127.116.11 by adding the following to the end of the section:
The effects of uplift shall be explicitly accounted for in the analysis and in the testing of the isolator units.
ALLOWABLE RAIL DEFLECTION
|RAIL SIZE (weight per foot of length, pounds)||WIDTH OF MACHINED SURFACE (inches)||ALLOWABLE RAIL DEFLECTION (inches)|
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.