Peer-to-Peer Standards Exchange

Hello everyone. Are the USD load combinations in ASCE 113 2nd Ed, Table 3-18 limited to 300 year MRI wind speeds or can these load combinations be used in conjunction with wind speeds pertaining to longer MRIs (obtained from ASCE 7-22)? 

Section 3.1.5.4 seems to suggest longer MRIs may be obtained from ASCE 7-22 but the load combinations in Table 3-18 specifically cite 300 yr wind speeds.

#WindandWindLoads
#ASCE7-22
#LoadCombinations

Alexander

I am unfamiliar with the ASCE 113 standard but observe that these load combinations (posted in your email) use somewhat load factors on D and other loads, as compared to ASCE 7 as well as the reduced wind speed.   Both the loads and load combinations specified in ASCE 7 have been calibrated to provide the target reliabilities indicated in Section 1.3 of the Standard.  I am unaware of the reliabilities targeted by ASCE 113, however, the use of reduced loads and load factors relative to ASCE 7 suggests that lower reliability (higher probability of failure) is targeted by the ASCE 113 standard.  If one were to use ASCE 7 wind loads rather than W300, together with the ASCE 113 load combinations, the resulting structure would have higher reliability (for wind-induced failure) but less than that targeted by the ASCE 7 standard.  It is impossible to say how much higher this reliability would be without conducting extensive studies.  I would say in response to your question that is possible and should be permissible to use the ASCE 7 wind speeds with the ASCE 113 standard.  This will result in improved structural performance to an undetermined extent.

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Ronald Hamburger, SE
Consulting Principal
Simpson Gumpertz & Heger
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