Every stamped seismic anchor calculation in California traces back to two documents working in tandem: ASCE 7-22 §13.4 sets the seismic demand on the anchor, and ACI 318-19 Chapter 17 sets the anchor's capacity. Mix them up — or apply one without the other — and the calculation fails plan-check.

Why two codes, not one?

ASCE 7-22 is a loading standard. It tells you how big the seismic force on the nonstructural component is (the Fp equation) and when to amplify that force for over-strength (Ω0p). ACI 318-19 is a capacity standard. Once the force gets to the anchor, ACI 318-19 Chapter 17 governs every limit state — steel rupture, concrete breakout, pullout, side-face blowout, pryout, and the §17.8 combined tension–shear interaction. A complete PE-stamped seismic anchor calculation package satisfies both.

The hand-off: Ω0p from ASCE to ACI

The clean hand-off between the two codes happens at one specific clause: ASCE 7-22 §13.4.2. When the anchor's strength is governed by a brittle concrete failure mode (breakout, pullout, side-face blowout), ASCE requires the anchor force to be amplified by the over-strength factor Ω0p from Table 13.5-1 / 13.6-1. That amplified force is what you carry into the ACI 318-19 §17.6 and §17.7 checks. Steel-controlled checks (§17.5) use the un-amplified Fp.

Then ACI 318-19 §17.10.6 imposes an additional 0.75 reduction on the concrete-governed nominal strength when the structure is in SDC C–F. Skip this and you're over-stating capacity by 33%.

The 8-section cheat sheet

Print this. It's the spine of every stamped seismic anchor calculation:

  • ASCE 7-22 §13.3.1 — Fp horizontal seismic force on the component.
  • ASCE 7-22 §13.3.2 — Fv vertical seismic component (±0.2·SDS·Wp).
  • ASCE 7-22 §13.3.3 — Fp,min and Fp,max bounds.
  • ASCE 7-22 §13.4.2 — Ω0p amplification for concrete-controlled anchorage.
  • ACI 318-19 §17.5 — Steel strength of anchor in tension and shear.
  • ACI 318-19 §17.6 / 17.7 — Concrete breakout, pullout, side-face blowout, pryout.
  • ACI 318-19 §17.8 — Combined tension–shear interaction (the final D/C check).
  • ACI 318-19 §17.10.6 — 0.75 seismic reduction on concrete-governed strength (SDC C–F).

Three places engineers most often miss the hand-off

After reviewing hundreds of calculation packages from contractors and OEMs, three failure patterns repeat:

  1. Forgetting Ω0p on post-installed anchors. Many spreadsheets assume the steel limit state governs and skip the amplification. If the breakout governs (very common with shallow anchors near edges), the calc is non-conservative. See our Ω0 over-strength amplification guide.
  2. Using uncracked concrete by default. ACI 318-19 §17.6.2.6 requires the cracked-concrete assumption unless analysis proves otherwise. See our cracked vs uncracked concrete guide.
  3. Skipping the §17.8 interaction. Each anchor must pass tension and shear individually, then the combined ratio must satisfy (Nua/φNn)5/3 + (Vua/φVn)5/3 ≤ 1.0.

What a stamped package looks like

A complete PE/SE stamped seismic anchor calculation from PANACHE traces every value back to one of the eight sections above. No black-box outputs, no proprietary spreadsheets without code traceability. Every page carries the wet stamp and every limit state is shown — even the ones that don't govern — so the AHJ reviewer can verify the design path in a single read.

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