CBC · California Building Code

How does the CBC coordinate concrete terminology with ACI 318 and ASCE 7?

The CBC says that whenever concrete provisions refer to "design displacement" you must use ASCE 7’s Design Earthquake Displacement (δDE), and you may take diaphragm deformation δdi as zero only when ASCE 7 lets you treat the diaphragm as rigid (§ 1902.1, § 1902.1.1) .

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Last reviewed: July 5, 2026

What the code requires

The CBC directs that terminology used in ACI 318 and ASCE 7 be coordinated, and it explicitly fixes which earthquake-displacement term ACI 318 design provisions must use: "Design displacement" in the concrete provisions is the Design Earthquake Displacement, δDE, as defined in ASCE 7 Section 12.8.6.3. For diaphragms that ASCE 7 permits to be idealized as rigid, the displacement due to diaphragm deformation, δdi, may be taken as zero. This coordination is established in § 1902.1 and § 1902.1.1 of the CBC .

Requirements in detail

Scope and purpose

  • § 1902.1: The CBC requires that where ACI 318 and ASCE 7 use related terminology (particularly for earthquake displacement), those terms be coordinated according to § 1902.1.1 .
  • § 1902.1.1: Unambiguously states that "design displacement" = the Design Earthquake Displacement, δDE (ASCE 7 § 12.8.6.3). It also allows δdi = 0 for diaphragms that ASCE 7 allows to be idealized as rigid (ASCE 7 § 12.3.1.2) .

Decision‑relevant dimensions/values

Decision item CBC interpretation / action required When to use Code reference
Definition of "Design displacement" Use Design Earthquake Displacement (δDE) from ASCE 7 Always where ACI 318 calls for "design displacement" in CBC-governed concrete design § 1902.1.1
Diaphragm deformation displacement (δdi) Allowed to be taken as zero when diaphragm is permitted to be idealized as rigid by ASCE 7 When ASCE 7 § 12.3.1.2 conditions for rigid diaphragm hold § 1902.1.1
Source standards for concrete materials/testing Materials, concrete and testing shall comply with the applicable standards listed in ACI 318 ACI 318 (as adopted/modified by CBC) governs test/spec requirements § 1903.1

How it affects concrete design and detailing

  • When ACI 318 requires a displacement capacity or uses the term "design displacement," the CBC tells the user to substitute the ASCE 7 δDE (not another displacement definition). This aligns the seismic displacement input ACI 318 expects with ASCE 7 seismic procedures per § 1902.1.1 .
  • For diaphragm design and for elements whose seismic deformation demand depends on diaphragm behavior, the CBC permits setting δdi = 0 when ASCE 7 classifies the diaphragm as rigid (so that diaphragm deformation does not add to element displacement demand) — but only when ASCE 7's rigid-diaphragm criteria are satisfied (§ 1902.1.1) .

Exceptions & special cases

  • The CBC text itself provides the specific allowance for δdi = 0 only when the diaphragm meets ASCE 7's rigid‑diaphragm idealization conditions (§ 1902.1.1). The CBC does not change ASCE 7's criteria for deciding rigidity; you must evaluate those criteria in ASCE 7 .
  • The CBC ties concrete material/testing standards to ACI 318 (see § 1903.1); exceptions and OSHPD/DSA administrative supplements elsewhere in Chapter 19 can modify or further restrict application for specialized enforcement jurisdictions — check those supplemental sections when they apply .
  • If ASCE 7 requires a computed δDE that includes diaphragm deformation for a flexible diaphragm, the designer must use the full δDE (including δdi) in the ACI 318-related checks called for by CBC; the CBC only permits setting δdi = 0 where ASCE 7 authorizes a rigid-diaphragm idealization (§ 1902.1.1) .

Common mistakes

  • Treating "design displacement" as a different ACI-318 internal term rather than substituting ASCE 7’s δDE. The CBC mandates using δDE for the CBC-controlled interpretation of "design displacement" (§ 1902.1.1) .
  • Zeroing δdi without verifying ASCE 7's rigid‑diaphragm criteria. CBC permits δdi = 0 only when ASCE 7 allows idealizing the diaphragm as rigid (§ 1902.1.1) .
  • Overlooking that CBC separately adopts ACI 318 standards for materials/testing (§ 1903.1) and also contains multiple CBC amendments to ACI 318 elsewhere (so follow CBC modifications as well as the referenced standards) .

Worked example

Scenario (illustrative): The structural engineer computes, per ASCE 7 procedures, a Design Earthquake Displacement δDE = 0.50 in for a certain story. ASCE 7 evaluation shows the roof diaphragm meets the rigid-diaphragm idealization criteria in ASCE 7 § 12.3.1.2.

How the CBC directs use of those numbers:

  1. Per CBC § 1902.1.1, "design displacement" in ACI 318 items controlled by CBC equals δDE from ASCE 7. So the design displacement to be used in the ACI‑318‑referenced checks is δDE = 0.50 in .
  2. Because ASCE 7 permits the diaphragm to be idealized as rigid, CBC § 1902.1.1 permits taking δdi = 0; therefore diaphragm deformation need not be added separately to the element displacement demand in those concrete checks governed by ACI 318 under the CBC .
  3. If the same diaphragm were judged flexible per ASCE 7, the designer would include δdi as computed per ASCE 7 in the δDE value used for ACI 318 work called for by the CBC.

Note: the CBC text tells you which ASCE 7 displacement term to use but does not itself reproduce ASCE 7 calculation procedures — compute δDE and assess rigidity using ASCE 7 as the code of reference, then apply CBC § 1902.1.1 to feed those results into concrete design .

Related provisions

  • § 1902.1 — Coordination of terminology; points to § 1902.1.1 for the specific rule .
  • § 1902.1.1 — Design displacement is δDE; δdi allowed zero for rigid diaphragms .
  • § 1903.1 — Materials, concrete and testing shall comply with the applicable standards listed in ACI 318 (see CBC adoption of ACI standards) .
  • § 1904.1 — Durability requirements for structural concrete reference ACI 318 provisions (CBC adoption of ACI durability rules) .
  • § 1905.1 — Structural concrete must comply with ACI 318 in addition to CBC seismic provisions; CBC makes targeted modifications to ACI 318 elsewhere in Chapter 19 (see Chapter 19A/1909A for modifications) .

Code references

Grounded in the retrieved California Building Code — click a citation to read the verbatim passage:

  • CBC § 1901.7.1 High relevance — show source text

    1901.7.1 Cast-in-place concrete tolerances. Structural tolerances for cast-in-place concrete structural elements shall be in accordance with ACI 117.

    Exceptions:

    1. Group R-3 detached one- or two-family dwellings are not required to comply with this section.
    2. Shotcrete is not required to comply with this section.

    1901.7.2 Precast concrete tolerances. Structural tolerances for precast concrete structural elements shall be in accordance with ACI ITG-7.

    Exception: Group R-3 detached one- or two-family dwellings are not required to comply with this section.

    SECTION 1902—COORDINATION OF TERMINOLOGY

    1902.1 General. Coordination of terminology used in ACI 318 and ASCE 7 shall be in accordance with Section 1902.1.1.

    1902.1.1 Design displacement. Design displacement shall be the Design Earthquake Displacement, δ DE, defined in ASCE 7 Section 12.8.6.3. For diaphragms that can be idealized as rigid in accordance with ASCE 7 Section 12.3.1.2, δ di, displacement due to diaphragm deformation corresponding to the design earthquake, is permitted to be taken as zero.

    SECTION 1903—SPECIFICATIONS FOR TESTS AND MATERIALS

    1903.1 General. Materials used to produce concrete, concrete itself and testing thereof shall comply with the applicable standards listed in ACI 318.

    Exception: The following standards as referenced in Chapter 35 shall be permitted to be used.

    1. ASTM C150

    2. ASTM C595

    3. ASTM C1157

    1903.2 Glass fiber-reinforced concrete. Glass fiber-reinforced concrete (GFRC) and the materials used in such concrete shall be in accordance with the PCI 128.

    1903.3 Flat wall insulating concrete form (ICF) systems. Insulating concrete form material used for forming flat concrete walls shall conform to ASTM E2634. [OSHPD 1R, 2 & 5] Not Permitted by OSHPD.

    1903.4 Steel fiber reinforcement - [OSHPD 1R, 2 & 5] Not permitted by OSHPD.

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    1903.5 Welding of reinforcing bars - [OSHPD 1R, 2 & 5] Modify ACI 318 Section 26.6.4.1(b) by adding the following:

  • CBC § 1901.4 High relevance — show source text

    _ Screw-type anchors tested with a calibrated torque wrench shall attain the specified torque within one-quarter ( [ 1] / 4 ) turn of the screw after initial seating of the screw head.

    1901.4 Composite structural steel and concrete structures. Systems of structural steel acting compositely with reinforced concrete shall be designed in accordance with Section 2206 of this code.

    1901.5 Construction documents. The construction documents for structural concrete construction shall include:

    1. The specified compressive strength of concrete at the stated ages or stages of construction for which each concrete element is designed.

    2. The specified strength or grade of reinforcement.

    3. The size and location of structural elements, reinforcement and anchors.

    4. Provision for dimensional changes resulting from creep, shrinkage and temperature.

    5. The magnitude and location of prestressing forces.

    6. Anchorage length of reinforcement and location and length of lap splices.

    7. Type and location of mechanical and welded splices of reinforcement.

    8. Details and location of contraction or isolation joints specified for plain concrete.

    9. Minimum concrete compressive strength at time of posttensioning.

    10. Stressing sequence for posttensioning tendons.

    11. For structures assigned to Seismic Design Category D, E or F, a statement if slab on grade is designed as a structural diaphragm.

    1901.6 Special inspections and tests. S pecial inspections and tests of concrete elements of buildings and structures and concreting operations shall be as required by Chapter 17.

    1901.7 Tolerances for structural concrete. Where not indicated in construction documents, structural tolerances for concrete structural elements shall be in accordance with this section.

    1901.7.1 Cast-in-place concrete tolerances. Structural tolerances for cast-in-place concrete structural elements shall be in accordance with ACI 117.

    Exceptions:

    1. Group R-3 detached one- or two-family dwellings are not required to comply with this section.
    2. Shotcrete is not required to comply with this section.

    1901.7.2 Precast concrete tolerances. Structural tolerances for precast concrete structural elements shall be in accordance with ACI ITG-7.

    Exception: Group R-3 detached one- or two-family dwellings are not required to comply with this section.

    SECTION 1902—COORDINATION OF TERMINOLOGY

    1902.1 General. Coordination of terminology used in ACI 318 and ASCE 7 shall be in accordance with Section 1902.1.1.

    1902.1.1 Design displacement. Design displacement shall be the Design Earthquake Displacement, δ DE, defined in ASCE 7 Section 12.8.6.3. For diaphragms that can be idealized as rigid in accordance with ASCE 7 Section 12.3.1.2, δ di, displacement due to diaphragm deformation corresponding to the design earthquake, is permitted to be taken as zero.

    SECTION 1903—SPECIFICATIONS FOR TESTS AND MATERIALS

    1903.1 General. Materials used to produce concrete, concrete itself and testing thereof shall comply with the applicable standards listed in ACI 318.

    Exception: The following standards as referenced in Chapter 35 shall be permitted to be used.

    1. ASTM C150

    2. ASTM C595

    3. ASTM C1157

  • CBC § 19A-3 High relevance — show source text

    1901 A .6 Special inspections and tests. S pecial inspections and tests of concrete elements of buildings and structures and concreting operations shall be as required by Chapter 17A and Section 1910A.

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    1901 A .7 Tolerances for structural concrete. Where not indicated in construction documents, structural tolerances for concrete structural elements shall be in accordance with this section.

    1901 A .7.1 Cast-in-place concrete tolerances. Structural tolerances for cast-in-place concrete structural elements shall be in accordance with ACI 117.

    Exceptions:

    1. Group R-3 detached one- or two-family dwellings are not required to comply with this section.
    2. Shotcrete is not required to comply with this section. [DSA-SS] Tolerances for shotcrete construction shall be defined by the construction documents.

    1901 A .7.2 Precast concrete tolerances. Structural tolerances for precast concrete structural elements shall be in accordance with ACI ITG-7.

    Exception: Group R-3 detached one- or two-family dwellings are not required to comply with this section.

    SECTION 1902 A —COORDINATION OF TERMINOLOGY

    1902 A .1 General. Coordination of terminology used in ACI 318 and ASCE 7 shall be in accordance with Section 1902 A .1.1.

    1902 A .1.1 Design displacement. Design displacement shall be the Design Earthquake Displacement, δ DE, defined in ASCE 7 Section 12.8.6.3. For diaphragms that can be idealized as rigid in accordance with ASCE 7 Section 12.3.1.2, δ di, displacement due to diaphragm deformation corresponding to the design earthquake, is permitted to be taken as zero.

    SECTION 1903 A —SPECIFICATIONS FOR TESTS AND MATERIALS

    1903 A .1 General. Materials used to produce concrete, concrete itself and testing thereof shall comply with the applicable standards listed in ACI 318.

    1903 A .2 Glass fiber-reinforced concrete. Glass fiber-reinforced concrete (GFRC) and the materials used in such concrete shall be in accordance with the PCI 128.

    1903 A .3 Flat wall insulating concrete form (ICF) systems. Insulating concrete form material used for forming flat concrete walls shall conform to ASTM E2634. [OSHPD 1 & 4] Not permitted by OSHPD. [DSA-SS] ICF systems shall be considered alternative systems. Concrete constructed using ICF systems and attachments to ICF shall be designed for loads in accordance with this code and shall comply with manufacturer’s instructions and industry standards determined applicable by the enforcement agency. Calculations and drawings shall be submitted to the enforcement agency for review and approval prior to construction.

    1903A.4 Steel fiber reinforcement – Not permitted.

  • CBC § 19A-3 High relevance — show source text

    1901 A .3 Anchoring to concrete. Anchoring to concrete shall be in accordance with ACI 318 as supplemented in Section 1905 A, and applies to cast-in (headed bolts, headed studs and hooked J- or L-bolts), post-installed expansion (torque-controlled and displacement-controlled), undercut, screw, and adhesive anchors.

    1901 A .4 Composite structural steel and concrete structures. Systems of structural steel acting compositely with reinforced concrete shall be designed in accordance with Section 2206 A of this code.

    1901 A .5 Construction documents. The construction documents for structural concrete construction shall include:

    1. The specified compressive strength of concrete at the stated ages or stages of construction for which each concrete element is designed.
    2. The specified strength or grade of reinforcement.
    3. The size and location of structural elements, reinforcement and anchors.
    4. Provision for dimensional changes resulting from creep, shrinkage and temperature.
    5. The magnitude and location of prestressing forces.
    6. Anchorage length of reinforcement and location and length of lap splices.
    7. Type and location of mechanical and welded splices of reinforcement.
    8. Details and location of contraction or isolation joints.
    9. Minimum concrete compressive strength at time of posttensioning.
    10. Stressing sequence for posttensioning tendons.
    11. For structures assigned to Seismic Design Category D, E or F, a statement if slab on grade is designed as a structural diaphragm. 12. Openings larger than 12 inches (305 mm) in any dimension shall be detailed on the structural drawings.

    1901 A .6 Special inspections and tests. S pecial inspections and tests of concrete elements of buildings and structures and concreting operations shall be as required by Chapter 17A and Section 1910A.

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    1901 A .7 Tolerances for structural concrete. Where not indicated in construction documents, structural tolerances for concrete structural elements shall be in accordance with this section.

    1901 A .7.1 Cast-in-place concrete tolerances. Structural tolerances for cast-in-place concrete structural elements shall be in accordance with ACI 117.

    Exceptions:

    1. Group R-3 detached one- or two-family dwellings are not required to comply with this section.
    2. Shotcrete is not required to comply with this section. [DSA-SS] Tolerances for shotcrete construction shall be defined by the construction documents.

    1901 A .7.2 Precast concrete tolerances. Structural tolerances for precast concrete structural elements shall be in accordance with ACI ITG-7.

    Exception: Group R-3 detached one- or two-family dwellings are not required to comply with this section.

    SECTION 1902 A —COORDINATION OF TERMINOLOGY

    1902 A .1 General. Coordination of terminology used in ACI 318 and ASCE 7 shall be in accordance with Section 1902 A .1.1.

  • CBC § 3.11.1 Medium relevance — show source text

    1810 A .3.11.1 Seismic Design Categories C through F. For structures assigned to Seismic Design Category C, D, E or F, concrete deep foundation elements shall be connected to the pile cap in accordance with ACI 318.

    For resistance to uplift forces, anchorage of steel pipes, tubes or H-piles to the pile cap shall be made by means other than concrete bond to the bare steel section. Concrete-filled steel pipes or tubes shall have reinforcement of not less than 0.01 times the cross-sectional area of the concrete fill developed into the cap and extending into the fill a length equal to two times the required cap embedment, but not less than the development length in tension of the reinforcement.

    1810 A .3.11.2 Seismic Design Categories D through F. For structures assigned to Seismic Design Category D, E or F, deep foundation element resistance to uplift forces or rotational restraint shall be provided by anchorage into the pile cap, designed considering the combined effect of axial forces due to uplift and bending moments due to fixity to the pile cap. Anchorage shall develop not less than 25 percent of the strength of the element in tension. Anchorage into the pile cap shall comply with the following:

    1. In the case of uplift, the anchorage shall be capable of developing the least of the following: 1.1. The nominal tensile strength of the longitudinal reinforcement in a concrete element. 1.2. The nominal tensile strength of a steel element. 1.3. The frictional force developed between the element and the soil multiplied by 1.3. [DSA-SS, DSA-SS/CC] Not permitted by DSA. Exception: The anchorage is permitted to be designed to resist the axial tension force resulting from the seismic load effects including overstrength factor in accordance with Section 2.3.6 or 2.4.5 of ASCE 7.
    2. In the case of rotational restraint, the anchorage shall be designed to resist the axial and shear forces, and moments resulting from the seismic load effects including overstrength factor in accordance with Section 2.3.6 or 2.4.5 of ASCE 7 or the anchorage shall be capable of developing the full axial, bending and shear nominal strength of the element.
    3. The connection between the pile cap and the steel H-piles or unfilled steel pipe piles in structures assigned to Seismic Design Category D, E or F shall be designed for a tensile force of not less than 10 percent of the pile compression capacity. Exception: Connection tensile capacity need not exceed the strength required to resist seismic load effects including overstrength of ASCE 7 Section 12.4.3 or 12.14.3.2.

    Where the vertical lateral-force-resisting elements are columns, the pile cap flexural strengths shall exceed the column flexural strength. The connection between batter piles and pile caps shall be designed to resist the nominal strength of the pile acting as a short column. Batter piles and their connection shall be designed to resist forces and moments that result from the application of seismic load effects including overstrength factor in accordance with Section 2.3.6 or 2.4.5 of ASCE 7.

    1810 A .3.12 Grade beams. Grade beams shall comply with the provisions of ACI 318.

  • CBC § 1903.5 Medium relevance — show source text

    1903.5 Welding of reinforcing bars - [OSHPD 1R, 2 & 5] Modify ACI 318 Section 26.6.4.1(b) by adding the following:

    Subject to prior approval of the enforcing agency, longitudinal holding wires conforming to ASTM A1064, of maximum wire size W5, that are machine resistance welded to stirrup/tie cage (or spiral assemblies) consisting of low alloy steel reinforcing conforming to ASTM A706 are permitted when performed under continuous competent control in a fabrication shop. Tack welding of primary rein- forcing bars together or to stirrups/ties is not permitted. Holding wire weld locations shall not occur on any longitudinal or primary reinforcing nor on any portion of a reinforcing bar that is or will be bent in accordance with ACI 318 Section 25.3 for the extents speci- fied in AWS D1.4 Section 4.2.6.

    Quality control tests shall be performed on shop welded specimens by the fabricator. Reinforcing steel specimens containing the holding wire shall be tested for yield and tensile strength at the frequency required by Section 1910.2. Test reports shall be available on request to the approved agency, design professional and enforcement agency.

    SECTION 1904—DURABILITY REQUIREMENTS

    1904.1 Structural concrete. Structural concrete shall conform to the durability requirements of ACI 318.

    Exception: For Group R-2 and R-3 occupancies not more than three stories above grade plane, the specified compressive strength, f´ c, for concrete in basement walls, foundation walls, exterior walls and other vertical surfaces exposed to the weather shall be not less than 3,000 psi (20.7 MPa).

    1904.2 Nonstructural concrete. The registered design professional shall assign nonstructural concrete a freeze-thaw exposure class, as defined in ACI 318, based on the anticipated exposure of nonstructural concrete. Nonstructural concrete shall have a minimum specified compressive strength, f´ c, of 2,500 psi (17.2 MPa) for Class F0; 3,000 psi (20.7 MPa) for Class F1; and 3,500 psi (24.1 MPa) for Classes F2 and F3. Nonstructural concrete shall be air entrained in accordance with ACI 318.

    SECTION 1905—SEISMIC REQUIREMENTS

    1905.1 General. In addition to the provisions of ACI 318, structural concrete shall comply with the requirements of Section 1905.

    1905.2 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.

    DETAILED PLAIN CONCRETE STRUCTURAL WALL. A wall complying with the requirements of Chapter 14, and Section 1905.5 of the California Building Code .

    ORDINARY PLAIN CONCRETE STRUCTURAL WALL. A wall complying with the requirements of Chapter 14, excluding 14.6.2.

  • CBC § 31F-77 Medium relevance — show source text

    s = Spacing of hoops or spiral along the pile axis

    t = Steel pile wall thickness

    Δ = Displacement capacity

    θ = Angle of critical crack to the pile axis

    θ = Plastic rotation p α = Angle between line joining centers of flexural compression in the deck/pile and in-ground hinges, and the pile axis

    φ a = Allowable curvature

    φ m = Maximum curvature φ p, φ p,m = Plastic curvature φ u = Ultimate curvature φ ′ u = Adjusted ultimate curvature

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    MARINE OIL TERMINALS

    φ y = Yield curvature φ ′ y = Adjusted yield curvature

    τ = Maximum allowable shear stress capacity τ design = Design shear strength τ max = Maximum shear stress

    V c = Concrete shear strength v j = Nominal joint shear stress V design = Design shear strength V max = Maximum shear demand

    V n = Nominal shear strength V p = Contribution to shear strength from axial loads V s = Transverse reinforcement shear strength V pile = Shear strength of steel pile

    3107F.9 References.

    [7.1] Priestley, M.J.N, Seible, F. and Calvi, G.M. “Seismic Design and Retrofit of Bridges,” 1996, New York.

    [7.2] Ferritto, J., Dickenson, S., Priestley N., Werner, S., Taylor, C., Burke D., Seelig W., and Kelly, S., 1999, “Seismic Criteria for Califor- nia Marine Oil Terminals, Vol.1 and Vol.2,” Technical Report TR-2103-SHR, Naval Facilities Engineering Service Center, Port Hueneme, CA.

    [7.3] American Society of Civil Engineers (ASCE), 2017, ASCE/SEI 41-17 (ASCE/SEI 41), “Seismic Evaluation and Retrofit of Existing Buildings,” Reston, VA.

    [7.4] Blakeley, J.P., Park, R., “Prestressed Concrete Sections with Cyclic Flexure,” Journal of the Structural Division, American Society of Civil Engineers, Vol. 99, No. ST8, August1973, pp. 1 71 7-1 742, Reston, VA.

    [7.5] American Society of Civil Engineers (ASCE), 2014, ASCE/COPRI 61-14 (ASCE/COPRI 61), “Seismic Design of Piers and Wharves,” Reston, VA.

    [7.6] Port of Long Beach (POLB), 2012 February 29, “Wharf Design Criteria,” Version 3.0, Long Beach, CA.

    [7.7] American Concrete Institute (ACI), 2014, ACI 318-14 (ACI 318), “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14),” Farmington Hills, MI.

  • CBC § 1905.7.1 Medium relevance — show source text

    1905.7.1 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 or 12.14-1 shall be deemed to satisfy Section 17.10.5.3(d) of ACI 318.

    1905.7.2 Anchors in shear. The following exceptions are permitted to ACI 318 Section 17.10.6.2:

    Exceptions:

    1. 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.
    2. 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 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).

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    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.

  • CBC § 18.5 Medium relevance — show source text

    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:

    1. 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.
  • CBC § 1810.3.8 Medium relevance — show source text

    1810.3.8 Precast concrete piles. Precast concrete piles shall be designed and detailed in accordance with ACI 318.

    Exceptions:

    1. For precast prestressed piles in Seismic Design Category C, the minimum volumetric ratio of spirals or circular hoops required by Section 18.13.5.10.4 of ACI 318 shall not apply in cases where the design includes full consideration of load combinations specified in ASCE 7, Section 2.3.6 or Section 2.4.5 and the applicable overstrength factor, Ω 0 . In such cases, minimum transverse reinforcement index shall be as specified in Section 13.4.5.6 of ACI 318. [OSHPD 1R, 2 & 5] not permitted by OSHPD.
    2. For precast prestressed piles in Seismic Design Categories D through F and in Site Class A, B, BC, C, CD, D or DE sites, the minimum volumetric ratio of spirals or circular hoops required by Section 18.13.5.10.5(c) of ACI 318 shall not apply in cases where the design includes full consideration of load combinations specified in ASCE 7, Section 2.3.6 or Section 2.4.5 and the applicable overstrength factor, Ω 0 . In such cases, minimum transverse reinforcement shall be as specified in Section 13.4.5.6 of ACI 318. [OSHPD 1R, 2 & 5] not permitted by OSHPD.

    [OSHPD 1R, 2 & 5] Exception: Where the axial load from seismic forces is amplified by the applicable overstrength factor, Ω 0 , the axial load limits in Section 18.13.5.10.6 of ACI 318 may be increased by two times.

    1810.3.9 Cast-in-place deep foundations. Cast-in-place deep foundation elements shall be designed and detailed in accordance with Sections 1810.3.9.1 through 1810.3.9.6.

    1810.3.9.1 Design cracking moment. The design cracking moment ( φ M n ) for a cast-in-place deep foundation element not enclosed by a structural steel pipe or tube shall be determined using the following equation:

    18-26 2025 CALIFORNIA BUILDING CODE

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    SOILS AND FOUNDATIONS

    Equation 18-5

    φ M n = 3 f ′ c S m

    For SI: φ M n = 0.25 f ′ c S m

    where:

    f ′ c = Specified compressive strength of concrete or grout, psi (MPa). S m = Elastic section modulus, neglecting reinforcement and casing, cubic inches (mm [3] ).

  • CBC § 1810.2.2 Medium relevance — show source text

    Where deep foundation elements of the same type are being spliced, splices shall develop not less than 50 percent of the bending strength of the weaker section. Where deep foundation elements of different materials or different types are being spliced, splices shall develop the full compressive strength and not less than 50 percent of the tension and bending strength of the weaker section. Where structural steel cores are to be spliced, the ends shall be milled or ground to provide full contact and shall be full-depth welded.

    Exception: For buildings assigned to Seismic Design Category A or B, splices need not comply with the 50-percent tension and bending strength requirements where justified by supporting data.

    Splices occurring in the upper 10 feet (3048 mm) of the embedded portion of an element shall be designed to resist at allowable stresses the moment and shear that would result from an assumed eccentricity of the axial load of 3 inches (76 mm), or the element shall be braced in accordance with Section 1810.2.2 to other deep foundation elements that do not have splices in the upper 10 feet (3048 mm) of embedment.

    1810.3.6.1 Seismic Design Categories C through F. For structures assigned to Seismic Design Category C, D, E or F splices of deep foundation elements shall develop the lesser of the following:

    1. The nominal strength of the deep foundation element.
    2. The axial and shear forces and moments from the seismic load effects including overstrength factor in accordance with Section 2.3.6 or 2.4.5 of ASCE 7.

    1810.3.7 Top of element detailing at cutoffs. Where a minimum length for reinforcement or the extent of closely spaced confinement reinforcement is specified at the top of a deep foundation element, provisions shall be made so that those specified lengths or extents are maintained after cutoff.

    1810.3.8 Precast concrete piles. Precast concrete piles shall be designed and detailed in accordance with ACI 318.

    Exceptions:

    1. For precast prestressed piles in Seismic Design Category C, the minimum volumetric ratio of spirals or circular hoops required by Section 18.13.5.10.4 of ACI 318 shall not apply in cases where the design includes full consideration of load combinations specified in ASCE 7, Section 2.3.6 or Section 2.4.5 and the applicable overstrength factor, Ω 0 . In such cases, minimum transverse reinforcement index shall be as specified in Section 13.4.5.6 of ACI 318. [OSHPD 1R, 2 & 5] not permitted by OSHPD.
    2. For precast prestressed piles in Seismic Design Categories D through F and in Site Class A, B, BC, C, CD, D or DE sites, the minimum volumetric ratio of spirals or circular hoops required by Section 18.13.5.10.5(c) of ACI 318 shall not apply in cases where the design includes full consideration of load combinations specified in ASCE 7, Section 2.3.6 or Section 2.4.5 and the applicable overstrength factor, Ω 0 . In such cases, minimum transverse reinforcement shall be as specified in Section 13.4.5.6 of ACI 318. [OSHPD 1R, 2 & 5] not permitted by OSHPD.
  • CBC § 4.1.1.4 Medium relevance — show source text

    R401.4.1.1.4 Liability. A city, county, or city and county or other enforcement agency charged with the administration and enforcement of the provisions of Section R401.4.1.1, is not liable for any injury which arises out of any act or omission of the city, county or city and county, or other enforcement agency, or a public employee or any other person under Section R401.4.1.1.1, R401.4.1.1.2 or R401.4.1.1.3.

    R401.4.1.1.5 Alternate procedures. The governing body of any city, county, or city and county may enact an ordinance prescribing an alternate procedure which is equal to or more restrictive than the procedures specified in Sections R401.4.1.1.1, R401.4.1.1.2 and R401.1.1.3.

    R401.4.2 Compressible or shifting soil. Instead of a complete geotechnical evaluation, where top or subsoils are compressible or shifting, they shall be removed to a depth and width sufficient to ensure stable moisture content in each active zone and shall not be used as fill or stabilized within each active zone by chemical, dewatering or presaturation.

    SECTION R402—MATERIALS

    R402.1 Wood foundations. Wood foundation systems shall be designed and installed in accordance with the provisions of this code.

    R402.1.1 Fasteners. Fasteners used below grade to attach plywood to the exterior side of exterior basement or crawl-space wall studs, or fasteners used in knee wall construction, shall be of Type 304 or 316 stainless steel. Fasteners used above grade to attach plywood and all lumber-to-lumber fasteners except those used in knee wall construction shall be of Type 304 or 316 stainless steel, silicon bronze, copper, hot-dipped galvanized (zinc coated) steel nails, or hot-tumbled galvanized (zinc coated) steel nails. Electro-galvanized steel nails and galvanized (zinc coated) steel staples shall not be permitted.

    R402.1.2 Wood treatment. Lumber and plywood shall be pressure-preservative treated and dried after treatment in accordance with AWPA U1 (Commodity Specification A, Special Requirement 4.2), and shall bear the label of an accredited agency. Where lumber or plywood is cut or drilled after treatment, the treated surface shall be field treated with copper naphthenate, the concentration of which shall contain not less than 2-percent copper metal, by repeated brushing, dipping or soaking until the wood cannot absorb more preservative.

    R402.2 Concrete. Concrete shall have a minimum specified compressive strength of f′ c, as shown in Table R402.2. Concrete subject to moderate or severe weathering as indicated in Table R301.2 shall be air entrained as specified in Table R402.2. The maximum weight of fly ash, other pozzolans, silica fume, slag or blended cements that is included in concrete mixtures for garage floor slabs and for exterior porches, carport slabs and steps that will be exposed to deicing chemicals shall not exceed the percentages of the total weight of cementitious materials specified in Section 19.3.3.4 of ACI 318. Materials used to produce concrete and testing thereof shall comply with the applicable standards listed in Chapters 19 and 20 of ACI 318 or ACI 332.

    |TABLE R402.

Frequently asked questions

If CBC says "design displacement = δDE," does that mean I never use any other displacement term from ACI 318?

No. The CBC clarifies that when the CBC-controlled text uses the phrase "design displacement" you must use the ASCE 7 Design Earthquake Displacement (δDE). Other ACI 318 internal terms still apply where ACI 318 itself defines them, but for the CBC-adopted concrete checks the CBC ties "design displacement" to ASCE 7’s δDE (§ 1902.1.1) .

When may I set δdi = 0?

Only when ASCE 7 permits idealizing the diaphragm as rigid (ASCE 7 § 12.3.1.2). The CBC § 1902.1.1 explicitly permits taking δdi = 0 under those ASCE 7 conditions .

Does the CBC replace ASCE 7 or ACI 318 procedures for computing δDE?

No. The CBC references and coordinates terminology — it assigns which ASCE 7 term to use in ACI 318 contexts. You must compute δDE and evaluate diaphragm rigidity using ASCE 7; the CBC then tells you to use that δDE for the CBC-governed ACI 318 requirements (§ 1902.1.1) .

Are there CBC-modified provisions to ACI 318 I should watch for?

Yes. Chapter 19 contains CBC modifications and additions to ACI 318 (see e.g., the 1909A series and other seismic-related sections). Always check Chapter 19 amendments in addition to the basic ACI 318 text when designing by reference to ACI 318 under the CBC .

If my enforcement agency has OSHPD/DSA authority, does that change this coordination?

Possibly. The CBC text includes supplemental notes and restrictions for OSHPD/DSA in various places; those jurisdictions add or restrict some uses of ACI provisions. Check the applicable local supplements in Chapter 19 (and the A-appendices) for site‑specific or occupancy‑specific modifications .

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