Safety analysis of steel building frames under dynamic wind loading

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Title: Safety analysis of steel building frames under dynamic wind loading
Author: Das, Nirmal K
Abstract: Absolute safety of a structure cannot be achieved because of uncertainties in loading and resistance . Conventional safety factors only qualitatively account for these uncertainties . Thus , the actual risk of failure of a structure designed in accordance with building code provisions remains unknown . Conversely , the probability of attaining a suitably specified limit state is recognized as a quantitative measure of safety . Since such information is needed in determining acceptable risk levels and in decision -making for structural improvements , a method for the evaluation of risk of failure is needed . Traditionally , wind -excited structures have been designed based on equivalent static forces in place of actual dynamic loads . For flexible buildings this may not always provide a reasonable approximation in the response analysis . The objective of this study is to evaluate the lifetime risk of failure of steel building frames subjected to dynamic wind loading . Risk is evaluated in terms of probability of excessive interfloor deflection . The method consists of the following studies : (1 ) estimation of the probabilities of exceedance of significant wind speeds at a specified site (wind hazard ) , (2 ) evaluation of the structural response statistics for a given storm intensity , using multiple time -histories of wind speed ; and (3 ) convolution of the wind hazard with the response exceedance probabilities for each loading intensity considered . The wind field model used is based on the Power Law profile and Davenport's gust spectrum . Wind speeds are generated by a simulation technique . Three steel buildings ranging from three to twenty stories are investigated using shear beam model . An ideal elasto -plastic force -deformation relationship is assumed , neglecting strain -hardening effects . A step -by -step integration method is employed for solving the governing differential equations . This study is restricted to low -rise /moderately tall (up to 20 stories ) rectangular steel buildings having equally spaced , laterally unbraced frames . Only along -wind responses are considered , neglecting wind directional effects .
URI: http : / /hdl .handle .net /2346 /15404
Date: 1988-05


Safety analysis of steel building frames under dynamic wind loading. Doctoral dissertation, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /15404 .

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