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Title:A Method for the Combination of Stochastic Time Varying Load Effects
Author(s):Pearce, Howard Thomas
Department / Program:Civil Engineering
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Civil
Abstract:The problem of computing the probability of failure of a structure under the combined action of a number of time varying load processes is studied. Loads arrive at points in a Poisson process and are modeled by deterministic shapes for static effects and by continuous random processes for dynamic effects.
Nonlinear limit surfaces are linearized for the computation of the crossing rate of the combined vector process which is then used to estimate the failure probability. Results given by the load coincidence method for combined dynamic processes are compared with those of the point crossing method and also with simplified methods (SRSS and Turkstra) used in certain structural codes. The simplified methods are unable to give consistent results for all probability levels and the point crossing method is found to be more conservative than the proposed load coincidence method. The accuracy of the method is investigated using more accurate estimates of the conditional first passage probabilities and by some Monte Carlo Simulation. Correlation between load intensity, duration, and occurrence is introduced into the model and the formulation modified to compute the failure probability. Correlation of intensities and occurrences between load processes are shown to be the most important dependence effects.
The use of the method studied is suggested in a procedure for developing more consistent risk-based structural codes. The method is found to be relatively simple, accurate and versatile in solving the general load combination problem.
Issue Date:1983
Description:154 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
Other Identifier(s):(UMI)AAI8410018
Date Available in IDEALS:2014-12-15
Date Deposited:1983

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