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Structural Research Series 533PDF


Title:Reliability-Based Structural Optimization Under Stochastic Time Varying Loads
Author(s):Kim, S.H.; Wen, Y.K.
Subject(s):Load combination
Abstract:Most optimization studies have been concerned with member or system geometry of structures under loads which are static or deterministic or both. The objective of this study is to develop a method for design under multiple stochastic loads based on optimization. The objective function such as cost is minimized under the constraint that the probabilities of various limit states being reached are within allowable limit. The loads are treated as random processes and their possible combined effect evaluated by the load coincidence method. The limit states considered are either yielding or first plastic hinge at the member level or plastic collapse at the system level. A penalty function approach and a Sequential Unconstrained Minimization (SUMT) method are used. Sensitivity studies with respect to the loading parameters are carried out. It is found that an optimization-based design satisfying the constraints at the member levels, may not have desirable system reliability and vice versa. A balanced design using a bi-level (member and system reliability constraints is proposed and shown to yield more risk consistent results. Also current design formats are examined. An improvement is introduced by adding a load combination formula including all loads under consideration.
Issue Date:1987-02
Publisher:University of Illinois Engineering Experiment Station. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Civil Engineering Studies SRS-533
Genre:Technical Report
Sponsor:National Science Foundation Grants CEE 82-07590 and DFR 84-14284
Date Available in IDEALS:2009-11-04
Identifier in Online Catalog:1186130

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