1905A Seismic Requirements — 2025 California Building Code
California Building Code (Title 24, Part 2) · 2025 edition · updated 2026-09-25 · California
CBSC: official editions, supplements and errata
Italicized text is a California amendment to the model code, as printed in the official publication.
Cite as: 2025 California Building Code (Title 24, Part 2) § 1905A · Effective January 1, 2026 · Official source: Building Standards Commission
1905 A .1 General. In addition to the provisions of ACI 318, structural concrete shall comply with the requirements of Section 1905 A .
1905 A .2 ACI 318 Section 2.3. Modify existing definitions and add the following definitions to ACI 318 Section 2.3:
CAST-IN-PLACE CONCRETE EQUIVALENT DIAPHRAGM. A cast-in-place noncomposite topping slab diaphragm, as defined in Section 18.12.5, or a diaphragm constructed with precast concrete components that uses closure strips between precast components with detailing that meets the requirements of ACI 318 for the Seismic Design Category of the structure.
19A-4 2025 CALIFORNIA BUILDING CODE
CONCRETE
PRECAST CONCRETE DIAPHRAGM. A diaphragm constructed with precast concrete components, with or without a cast-in-place topping, that includes the use of discrete connectors or joint reinforcement to transmit diaphragm forces.
1905 A .3 Intermediate precast structural walls. Intermediate precast structural walls shall comply with Section 18.5 of ACI 318 and this section.
1905 A .3.1 Connections designed to yield. Connections that are designed to yield shall be capable of maintaining 80 percent of their design strength at the deformation induced by the design displacement or shall use Type 2 mechanical splices. [DSA-SS] Connections between wall panels and the foundation shall be designed per Section 1617A.1.15.
1905 A .4 Foundations designed to resist earthquake forces. Foundations resisting earthquake-induced forces or transferring earthquake-induced forces between a structure and the ground shall comply with the requirements of Section 18.13 of ACI 318 and other applicable provisions of ACI 318 unless modified by Chapter 18 A .
1905 A .5 Detailed plain concrete structural walls. Not permitted.
1905 A .6 Structural plain concrete. Not permitted.
1905 A .7 Design requirements for anchors. For the design requirements for anchors, Sections 1905 A .7.1 and 1905 A .7.2 provide exceptions that are permitted to ACI 318.
1905 A .7.1 Anchors in tension. The following exception is permitted to ACI 318 Section 17.10.5.2:
Exception: Anchors designed to resist wall out-of-plane forces with design strengths equal to or greater than the force determined in accordance with ASCE/SEI 7 Equation 12.11-1 and Section 1604A.8.2 of this code shall be deemed to satisfy Section 17.10.5.3(d) of ACI 318.
1905 A .7.2 Anchors in shear. The following exceptions are permitted to ACI 318 Section 17.10.6.2:
Exceptions:
- For the calculation of the in-plane shear strength of anchor bolts attaching wood sill plates of bearing or nonbearing walls of light-frame wood structures to foundations or foundation stemwalls, the in-plane shear strength in accordance with Sections 17.7.2 and 17.7.3 of ACI 318 need not be computed and Section 17.10.6.3 of ACI 318 shall be deemed to be satisfied provided that all of the following are met: 1.1. The allowable in-plane shear strength of the anchor is determined in accordance with ANSI/AWC NDS Table 12E for lateral design values parallel to grain. 1.2. The maximum anchor nominal diameter is 5/8 inch (16 mm). 1.3. Anchor bolts are embedded into concrete not less than 7 inches (178 mm). 1.4. Anchor bolts are located not less than 1¾ inches (45 mm) from the edge of the concrete parallel to the length of the wood sill plate. 1.5. Anchor bolts are located not less than 15 anchor diameters from the edge of the concrete perpendicular to the length of the wood sill plate. 1.6. The sill plate is 2-inch (51 mm) or 3-inch (76 mm) nominal thickness.
- For the calculation of the in-plane shear strength of anchor bolts attaching cold-formed steel track of bearing or nonbearing walls of light-frame construction to foundations or foundation stemwalls, the in-plane shear strength in accordance with Sections 17.7.2 and 17.7.3 of ACI 318 need not be computed and Section 17.10.6.3 shall be deemed to be satisfied provided that all of the following are met:
Allowable in-plane shear strength of exempt anchors, parallel to the edge of concrete, shall be permitted to be determined in accordance with AISI S100 Section J3.3.1.
2.1. The maximum anchor nominal diameter is 5/8 inch (16 mm). 2.2. Anchors are embedded into concrete a minimum of 7 inches (178 mm). 2.3. Anchors are located a minimum of 1 3/4 inches (45 mm) from the edge of the concrete parallel to the length of the track.
2.4. Anchors are located a minimum of 15 anchor diameters from the edge of the concrete perpendicular to the length of the track. 2.5. The track is 33 to 68 mil (0.84 mm to 1.73 mm) designation thickness. 3. In light-frame construction bearing or nonbearing walls, shear strength of concrete anchors less than or equal to 1 inch (25 mm) in diameter attaching sill plate or track to foundation or foundation stemwalls need not satisfy Sections 17.10.6.3(a) through (c) when the design strength of the anchors is determined in accordance with Section 17.7.2.1(c) of ACI 318.
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