Mean Recurrence Intervals of Failure Wind Loads

Published

August 1, 2008

Author(s)

Dat Duthinh, Joseph A. Main, Amelia P. Wright, Emil Simiu

Abstract

The Commentary to the ASCE Standard 7-05 states that the nominal mean recurrence interval (MRI) of the wind speed inducing the design strength is about 500 years if the specified load factor is 1.5, as in early versions of ASCE 7, and somewhat higher than 500 years if the specified load factor is 1.6, as in ASCE 7-05. However, the Commentary also states, it is not likely that the 500-year event is the actual speed at which engineered structures are expected to fail, due to resistance factors in materials, due to conservative design procedures that do not always analyze all load capacity, and due to a lack of a precise definition of failure. In this paper we propose a working definition of failure for steel structures using nonlinear finite element analysis, and we present a methodology for estimating the MRI of failure under wind loads that accounts in a detailed and rigorous manner for nonlinear structural behavior and for the directionality of the wind speeds and the aerodynamic effects. The methodology uses databases of wind tunnel pressure (database-assisted design), nonlinear finite-element analysis, and directional wind speeds from the NIST hurricane database augmented by statistical techniques. As a case study to illustrate the methodology, we consider a single frame of a steel industrial building. Under the assumption that uncertainties with respect to the parameters that determine the wind loading and to the material behavior are negligible, the minimum MRI of failure for the steel frame being investigated was found to be of the order of 100 000 years, which corresponds to a probability of 1/2000 that the frame will fail during a 50-year lifetime.

Citation

American Society of Civil Engineers Structures Journal

Volume

134

Issue

8

Pub Type

Journals

Download Paper

https://doi.org/10.1061/(ASCE)0733-9445(2008)134:8(1383)

Keywords

database-assisted design, failure, finite elements, mean recurrence intervals, nonlinear analysis, steel structures, wind direction effects, wind loads

Citation

Duthinh, D. , Main, J. , Wright, A. and Simiu, E. (2008), Mean Recurrence Intervals of Failure Wind Loads, American Society of Civil Engineers Structures Journal, [online], https://doi.org/10.1061/(ASCE)0733-9445(2008)134:8(1383) (Accessed April 19, 2024)