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ANSI A58.1-82 Seismic loads - Service or strength level?

ANSI A58.1-82 Seismic loads - Service or strength level?

(OP)
I have a building that is now covered by IBC 2006/ASCE7-05 and results in a Seismic category D. I am extending a mezzanine one bay beyond the existing bracing and adding a piece of equipment that is about 100 tons. I need to determine if my new loads will increase the existing brace forces by more than 10%. But I have no idea if the ANSI A58.1-1982 (the predecessor to ASCE7) seismic loads are strength or service level, and what the load combination were.

Does anyone have a copy of this entire specification or the seismic portion?

Unfortunately if the loads are more than 10%, I have to use a SCBF since OCBF are not allowed in D!

Thanks!

RE: ANSI A58.1-82 Seismic loads - Service or strength level?

pinballtime

My guess is that anything "US seismic" before 1994(The northridge event) was service level. In my copy of UBC'94 the load combination is simply dead + floor live + seismic or dead + floor live + snow + seismic, all unfactored. System behavior then was Rw, about 1.4 times the value we use now for R. Thus for steel OMF it was 8 compared to 5.6 we use now.

respects
ijr

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