Optimal Retrofitting of Structures Using Braces

Abstract:

The paper presents a mathematical programming based approach for the efficient retrofitting, with braces, of structures subjected to multiple load cases and serviceability limitations, simultaneously. The method is based on a simple ground structure concept that generates within a design domain all possible cross braces, and then automates the decision as to which brace members are retained or eliminated using unknown 0-1 variables. The optimization minimizes simultaneously the total number and volume of design braces. The governing problem takes the form of a disjunctive and combinatorial optimization program, cast as a mixed integer nonlinear programming (MINLP) problem. We propose a two-step optimization algorithm to solve the MINLP, in which the first step processes a standard nonlinear programming (NLP) problem by relaxing the binary variables to a continuous bounded system, the results of which form an initial basis for the second and final solve of the MINLP problem with binary variables.

• Periodical: Applied Mechanics and Materials (Volume 553)
• Pages: 807-812
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.553.807
• Online since: May 2014
• Authors: Sawekchai Tangaramvong*, Francis Tin-Loi
• Keywords: Brace Design, Ground Structure, Mixed Integer, Multiple Load Cases, Optimal Retrofit

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