Risk-Informed Mean Recurrence Intervals for Updated Wind Maps in ASCE 7-16

摘要

ASCE 7 is moving toward adopting load requirements that are consistent with risk-informed design goals characteristic of performance-based engineering (PBE). ASCE 7-10 provided wind maps that correspond to return periods of 300, 700, and 1,700years for Risk Categories I, II, and combined III/IV, respectively. The risk targets for Risk Categories III and IV buildings and other structures (designated as essential facilities) are different in PBE. The reliability analyses reported in this paper were conducted using updated wind load data to (1)confirm that the return periods already in ASCE 7-10 were also appropriate for risk-informed PBE, and (2)to determine a new risk-based return period for Risk Category IV. The use of data for wind directionality factor, Kd, which has become available from recent wind tunnel tests, revealed that reliabilities associated with wind load combinations for Risk Category II structures are, in fact, consistent with the reliabilities associated with the ASCE 7 gravity load combinations. This paper shows that the new wind maps in ASCE 7-16, which are based on return periods of 300, 700, 1,700, and 3,000years for Risk Categories I, II, III, and IV, respectively), achieve the reliability targets in Section 1.3.1.3 of ASCE 7-16 for nonhurricane wind loads.