Experimental study of deformable connection consisting of buckling-restrained brace and rubber bearings to connect floor system to lateral force resisting system

This paper presents experimental and numerical studies of a full-scale deformable connection used to connect the floor system of the flexible gravity load resisting system to the stiff lateral force resisting system (LFRS) of an earthquake-resistant building. The purpose of the deformable connection is to limit the earthquake-induced horizontal inertia force transferred from the floor system to the LFRS and, thereby, to reduce the horizontal floor accelerations and the forces in the LFRS. The deformable connection that was studied consists of a buckling-restrained brace (BRB) and steel-reinforced laminated low-damping rubber bearings (RB). The test results show that the force-deformation responses of the connection are stable, and the dynamic force responses are larger than the quasi-static force responses. The BRB+RB force-deformation response depends mainly on the BRB response. A detailed discussion of the BRB experimental force-deformation response is presented. The experimental results show that the maximum plastic deformation range controls the isotropic hardening of the BRB. The hardened BRB force-deformation responses are used to calculate the overstrength adjustment factors. Details and limitations of a validated, accurate model for the connection force-deformation response are presented. Numerical simulation results for a 12-story reinforced concrete wall building with deformable connections show the effects of including the RB in the deformable connection and the effect of modeling the BRB isotropic hardening on the building seismic response. Copyright (c) 2016 John Wiley & Sons, Ltd.