The 2025 California Building Code (CBC) adopts ASCE 7-22, and the most consequential changes for nonstructural component anchorage and certification live in Chapter 13. If you manufacture seismically certified equipment for California hospitals or you are a Design Professional in Responsible Charge (DPOR) on an HCAI project, the way you calculate the horizontal seismic design force Fp has changed — and so have the documents you submit to the Department of Health Care Access and Information (HCAI).

What changed in the Fp equation

Under ASCE 7-16, the horizontal seismic component force was familiar to nearly every preapproval engineer:

Fp=0.4 · ap · SDS · Wp·1 + 2·z/hRp / Ip
ASCE 7-16, Eq. 13.3-1

ASCE 7-22 replaces it with:

Fp=0.4 · SDS · Ip · Wp·HfRμ·CARRpo
ASCE 7-22, Eq. 13.3-1

The familiar upper and lower bounds — Fp,max = 1.6 · SDS · Ip · Wp and Fp,min = 0.3 · SDS · Ip · Wp — are unchanged. What is new is that Fp is now an explicit function of the building's Seismic Force Resisting System (SFRS).

The four new variables, in plain English

  • Hf — height amplification factor that replaces the old (1 + 2·z/h) term.
  • Rμ — ductility-based reduction factor tied to the building's SFRS (Table 12.2-1).
  • CAR — component resonance / amplification coefficient.
  • Rpo — component over-strength factor, replacing the lumped Rp.

Why preapproval capacities can no longer be expressed as just SDS + z/h

Historically, an OPM or OSP could publish a capacity table indexed by SDS and z/h. That is no longer sufficient. Per ASCE 7-22, capacity must also reflect Hf / Rμ, which depends on the host building's SFRS — information the manufacturer doesn't know in advance.

OSHPD's response is the component design force coefficient CP:

  • OPMs (analytical): CPm = 0.4 · SDS · Ip · (Hf/Rμ) · (CAR/Rpo) — used for supports and attachments.
  • OSPs (tested): CPs derived from AC156-style RRS accelerations — AFLX-H, ARIG-H, AFLX-V, ARIG-V.

Two DPOR roles, two responsibilities

  • Preapproval DPOR — publishes capacities in a form that lets project teams check demand against capacity efficiently across the full range of SFRS, height, and component conditions.
  • Project DPOR — calculates project-specific Fp using the actual SFRS, building height, and component location, then verifies it falls within the preapproval's published envelope.

Existing OPM/OSP under the 2025 CBC

Existing ASCE 7-16 preapprovals don't disappear — but they need to be evaluated for use under ASCE 7-22 demand levels. Force comparisons swing meaningfully in either direction depending on the SFRS and the component's location. New submittals must be prepared directly against the 7-22 framework, with Tables 13.5-1 and 13.6-1 providing the new component coefficients.

What to do now

  1. Audit your existing OPMs and OSPs. Identify components at risk of capacity shortfall under 7-22 demands.
  2. Restructure capacity tables. Move from SDS/z/h indexing to a CP-based envelope.
  3. Plan testing for new OSPs. AC156 RRS targets must be set against 7-22 floor accelerations.
  4. Document the SFRS assumption clearly.

How PANACHE ENGINEERING can help

Our team supports manufacturers through every stage of the OPM and OSP lifecycle — from preapproval calculations and capacity envelopes to AC156 shake table witness testing, fixture and restraint engineering, and project-side anchorage submittals. See our ASCE 7-22 Chapter 13 deep-dive or talk to an engineer.