The main effort on the buckling-restrained braces (BRBs) has been paid to find the strength and stiffness of the BRB cover. On the other hand, influence due to both friction and clearance between a steel brace and a BRB cover has not been investigated regaradless of important factors to influence the capability of BRB. The objectives of this study are to investigate the influence of friction and clearance between a steel brace and a BRB cover on the buckling-restrained brace behavior by using the finite element method. Obtained results through numerical analysis showed that the clearance make more influence compared to friction. Some obtained analytical results, which are relationship between applied force and deformation of steel braces of BRB covers, are verified through some experiments. The analytical results give good agreement with the results of the experiments. Finally, a simple design expression for BRB covers is proposed through analytical results.
