Experimental study of deformable connection consisting of friction device 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 friction device (FD) and carbon fiber-reinforced laminated low-damping rubber bearings (RB), denoted as the FD+RB connection. The test results show that the force-deformation responses of the FD+RB connection are stable under quasi-static sinusoidal and earthquake loading histories and dynamic sinusoidal loading histories. The FD+RB connection force-deformation response is approximated with a bilinear elastic-plastic force-deformation response with kinematic hardening. The FD is axially stiff, compact, easy-to-assemble, and able to accommodate the FD+RB connection kinematic requirements. The FD elastic stiffness controls the FD+RB connection elastic stiffness. The FD friction force controls the force when the FD+RB connection force-deformation response transitions from elastic to post elastic. The RB provide predictable and reliable post-elastic stiffness to the FD+RB connection. The machining tolerances for the FD components, the break-in effect, the sliding history, and the dwell time affect the FD friction force. Numerical simulation results for a 12-story reinforced concrete wall building with FD+RB connections under seismic loading show that a reduction of the FD friction force increases the FD+RB connection deformation demand.