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.3.3.4.4 and ACI 318-14 Section 17.2.3.4.4 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.4.3.5.4 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.