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AISC (ASD) Allowable Stress Increase for Wind/Seismic 1
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It should be noted that they didn't just remove the 1/3 increase by itself. It goes along with the newer ASCE 7 load combinations that include a 0.75 load factor on load combinations that include more than one transient load. An interesting history lesson on the subject is Ellifritt's article "The Mysterious 1/3 Stress Increase" in the AISC Engineering Journal, 4th Quarter 1977.
VoyageofDiscovery
Structural
0.75 on the load side is the same as 1/3 increase on the capacity side. So is this really a change?
VOD
VOD
It is not the same. The 1/3 increase was applied to stresses due to all types of load, including dead load. The 0.75 factor appearing in some of the ASCE equations only applies to two or more transient loads occuring at the same time, such as full live and full wind plus dead. Combinations such as dead and wind now receive no load reduction and no stress increase.
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Bagman2524
Structural
ASCE 7-98 sec 2.4.3 allows the 0.75 reduction with two transient loads, but if the loading with only one of the transient loads without the reduction produces more severe effect, then that load combination governs.
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