Buckling-restrained braces（BRBs）model and its sensitivity analysis algorithm based on direct differentiation method（DDM）are carried out using OpenSees.This model is able to predict the nonlinear behavior of BRB systems

and the DDM analysis results can provide the effect of constitutive parameters on structural response and show its relative importance.The research is useful for any gradient-based methods like structural optimization

structural reliability analysis

and model updating.A non-moment resisting 4-storey steel frame with BRBs subjected to accelerograms is studied to verify the correctness

accuracy and efficiency of the DDM algorithm. The influence of the constitutive parameters of each BRB on global and local response is also analyzed in this paper.In addition

response sensitivity results are used in updating a finite element model to verify the effect of the results on improving the algorithm efficiency.