Optimal design of the seismic retrofitting of reinforced concrete framed structures using BRBs

This paper studies the optimization process through the metaheuristic algorithm known as Simulated Annealing (SA) applied to a dissipative system formed by Buckling-Restrained Braces (BRBs) to improve the seismic behavior of existing RC framed buildings. The optimization algorithm is aimed at finding the solution with the minimum cost of the dissipative structure. During the process different aspects such as the distribution of the BRBs in the frame, the use of either short or long core BRBs, and other geometrical characteristics of the core were simultaneously considered. The seismic performance of all proposed designs was evaluated using the Capacity Spectrum Method. The SA algorithm was implemented in Matlab, creating a link between it and OpenSees, to allow the transfer of information during the optimization process. The use of both platforms proved to be efficient in the optimization of complex structures using metaheuristic algorithms. The results indicate that the proposed procedure is capable to find solutions with a significant saving of materials, used in the dissipative structure (up to 65%), compared to the solution obtained by a design method specialized in this kind of systems.