Anchor Knowledge Center SEISMIC DESIGN

SEISMIC DESIGN Anchoring-to-concrete provisions of the ACI 318 code Seismic design using the anchoring-to-concrete provisions of the ACI 318 code includes parameters that are not used when designing for static load conditions. These parameters are defined in ACI 318 Appendix D Part D.3.3 and ACI 318-14 Chapter 17 Section 17.2.3. Similarly, seismic-specific postinstalled anchor parameters derived from testing and evaluation per ICC-ES acceptance criteria and ACI test standards are given in ICC-ES Evaluation Reports (ESRs). ACI 318 anchoring-to-concrete provisions require a reduction factor of 0.75 to be applied to non-steel design strengths. ACI 318-08 Part D.3.3.3 requires this factor to be applied to both tension and shear non-steel design strengths. ACI 318-11 Part D. and ACI 318-14 Section require this factor to only be applied to non-steel tension design strengths. PROFIS Anchor designates the 0.75 reduction as “φseismic”. CSA A23.3-14 Annex D anchorage provisions follow the ACI 318-11 and ACI 318-14 provisions. Clause D. requires a 0.75 factor to only be applied to non-steel tension resistances. Parameters given in ESRs can also be specific to seismic load conditions. For example, Table 4 in ESR1917 for the Hilti Kwik Bolt TZ includes shear nominal steel strength values for seismic conditions, and designates these values as “Vsa,eq”. Mechanical anchor ESRs may include seismic-specific values for pullout, e.g. “Np,eq” in Table 3 in ESR-3027 for the Hilti Kwik HUS-EZ. Reduction factors having the designation “αxx,seis” are applied to adhesive anchor system design parameters. Referencing Table 11 in ESR-3814 for the Hilti HIT-RE 500 V3, note that the factor designated “αN,seis” is applied to the characteristic bond strength (τk,xxxx) when calculating nominal bond strength. Referencing Table 11 in ESR-3187 for the Hilti HIT-HY 200, note that the factor designated “αV,seis” is applied to the shear nominal steel strength (Vsa) when seismic load conditions are being considered. The ESRs for post-installed anchor systems qualified for seismic load conditions will also contain seismic-specific provisions (reference Section 4.1 in the ESR). Post-installed anchor design per CSA A23.3-14 Annex D will utilize the data and provisions given in the ESR for that anchor, including any seismic-specific data and provisions. View all approvals and reports for Hilti mechanical and adhesive anchor products in the US and Canada.