Why does PROFIS Anchor permit input of a variable value for the parameter Π nonductile when designing with ACI 318-08 seismic provisions? Per ACI 318-08 Part D.3.3.6, the reduction for brittle failure modes equals 0.4.
*Posted on behalf of a Hilti customer.
Dear Customer,
thank you for your question. The reduction applied to brittle failure mode design strengths that is referenced in ACI 318-08 Part D.3.3.6 is designated Πnonductile in PROFIS Anchor. The default value given in D.3.3.6 = 0.4; however, D.3.3.6 also permits use of a value = 0.5 for anchorage into a stud bearing wall. Section 1908.1.9 in the 2009 IBC waives the requirement to apply a reduction factor to brittle failure mode design strengths when anchoring a nonstructural component. It is also possible for a designer to utilize a reduction factor of their own choosing for brittle failure mode design strengths, based on the values for other seismic-related reduction factors and overstrength factors they have determined to be relevant for their anchorage design.
Therefore, PROFIS Anchor permits users to input a value designated “Πnonductile“ when designing per ACI 318-08 D.3.3.6 that ranges from 0.4 to 1.0. PROFIS Anchor defaults to a Πnonductile value of 0.4 when ACI 318-08 D.3.3.6 is selected as a seismic design option. Inputting a Πnonductile value of 1.0 would correspond to the 2009 IBC Section 1908.1.9 value for nonstructural components. Inputting a Πnonductile value between 0.4 and 1.0 could be used for an anchorage in a stud bearing wall, or when it has been determined to be relevant for a specific seismic anchorage design. I hope I have answered your question. If there is anything else, please let me know.
Kind Regards
Zachary