Mean Recurrence Intervals of Ultimate Wind Loads

Published

July 1, 1998

Author(s)

Emil Simiu, A N. Heckert, T Whalen

Abstract

The attention of wind engineers and extreme value climatologists has been focused in the last few decades on estimates of basic windspeeds, that is, wind speeds with 50 year or 100 year mean recurrence intervals (MRIs). Recently, however, efforts have been reported on MRI estimation for speeds inducing the design strength or causing member failure. These efforts have benefited from progress in extreme value theory, notably the development of peaks over threshold methods used in conjunction with the Generalized Pareto Distribution. According to results based on such methods, extreme wind speeds are best fitted by extreme value distributions of the reverse Weibull type. Unlike other distributions used in the past, these distributions have finite upper tails, as may be expected from the fact that, for physical reasons, storm intensities have finite upper bounds. We note results according to which the ASCE 7-93 Standard and its 1980s predecessors specify wind load factors that place structures in hurricane-prone regions at substantially higher risk than structures in non-hurricane regions, and comment on changes required in Standard provisions in this respect. We also review results on the effects of wind directionality. On average, estimates of wind loads with relatively short MRIs, obtained by disregarding wind directionality effects, are conservative in relation to estimates that take directionality into account. However, the conservatism decreases as the MRIs increase and may become marginal for speeds associated with wind-induced failures. We report and comment on the result that estimated tails of distributions that best fit samples of hurricane wind speeds are somewhat shorter than estimated tails for samples of squares of hurricane wind speeds. An Appendix provides instructions for accessing electronic files containing wind speed data and computer program listings.

Proceedings Title

Offshore Mechanics and Arctic Enginering (OMAE), 17th International Conference. Proceedings. American Society ofMechanical Engineers

Conference Dates

July 1, 1998

Conference Title

American Society of Mechanical Engineers

Pub Type

Conferences

Keywords

building technology, extreme values, statistics, structural engineering, ultimate loads, wind engineering

Citation

Simiu, E. , Heckert, A. and Whalen, T. (1998), Mean Recurrence Intervals of Ultimate Wind Loads, Offshore Mechanics and Arctic Enginering (OMAE), 17th International Conference. Proceedings. American Society ofMechanical Engineers (Accessed April 19, 2024)