Effect of buckling-restrained brace model parameters on seismic structural response

This paper illustrates the derivation of response sensitivities for a hysteretic model specifically developed for buckling-restrained braces (BRBs) in order to provide a tool that can be used to evaluate the effect of BRB constitutive parameters on structural response as well as a tool in gradient-based methods in structural optimization, structural reliability analysis, and model updating. The adopted BRB model, shown in an earlier study to give accurate predictions of the experimental behaviour of BRBs, is differentiated with respect to its material constitutive parameters using the direct differentiation method (DDM) and the obtained response sensitivities are validated by comparisons with the finite difference method (FDM). Results for a case study consisting of a steel frame with BRBs subjected to seismic input are reported to illustrate the influence on global and local structural response quantities of the BRB constitutive parameters. In addition, the derived response sensitivities are used in a simulated finite element model updating problem to show the efficiency of DDM over FDM. This work opens the way to many applications and potentialities such as sensitivity analysis of complex BRB design solutions, performance-based selection of optimal BRB properties, development and use of optimization-based design procedures.