Experimental study of deformable connection consisting of friction device and rubber bearings to connect floor system to lateral force resisting system

Abstract

Summary 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.

Shake‐table test performance of an inertial force‐limiting floor anchorage system

“…This positive result, not always anticipated in earlier analytical research, is attributed to the nature of rocking wall structure response, a combination of low LFRS overstrength and low‐rise structures, and the stiffness and strength of the GLRS, and requires further examination through analytical simulation. The force‐limiting components within the IFAS, both FDs and BRBs, provided well‐controlled strength, good energy dissipation, and sufficient deformation capacity to serve as effective devices for the IFAS. Some remaining issues for using a full‐scale FD in an actual implementation are reported in Tsampras et al The IFAS assemblage, FD or BRBs, RBs and bumpers, was able to perform as intended as a system, including the FD and BRB providing controllable force limiting and energy dissipation under the complex kinematics of an eccentric rocking wall structure; the RBs providing LFRS stabilization and restoring forces to minimize floor residual displacements; and the bumper limiting the relative displacement of the floor. The feasible design space identified from analytical parameter studies successfully produced an effective IFAS design and can be used as the basis for developing a design procedure for the IFAS and IFAS structure.…”

“…The force‐limiting components used for the shake‐table specimen are FDs and BRBs (Figure 8). These elements were selected, after careful review of many candidate devices and full‐scale testing, to provide the stable hysteretic energy dissipation, deformation capacity, and controllable strength required of the IFAS.…”

“…The FD assembly involved (Figure 8A): (1) clamped steel plates, consisting of a slotted internal sliding plate and 2 fixed external plates; (2) 8 friction bolts (A325, 19‐mm diameter) with lubricated bushings to reduce friction on the slots and Belleville washers for even preload; (3) a pair of thin AFT‐200 composite shim plates between the internal and external plates to better control the FD slip force; and (4) guiding plates to prevent rotation. The FD strength is easily adjusted by changing the bolt pretension force.…”

“…The force-limiting components used for the shake-table specimen are FDs and BRBs (Figure 8). These elements were selected, after careful review of many candidate devices 4 and full-scale testing, 27,28 to provide the stable hysteretic energy dissipation, deformation capacity, and controllable strength required of the IFAS. The FD assembly 27 involved ( Figure 8A): (1) clamped steel plates, consisting of a slotted internal sliding plate and 2 fixed external plates; (2) 8 friction bolts (A325, 19-mm diameter) with lubricated bushings to reduce friction on the slots and Belleville washers for even preload; (3) a pair of thin AFT-200 † composite shim plates between the internal and external plates to better control the FD slip force; and (4) guiding plates to prevent rotation.…”

Optimal Damper Slip Force for Vibration Control Structures Incorporating Friction Device with Sway‐Rocking Motion Obtained Using Shaking Table Tests

“…Wu et al have conducted an experimental study on reparability of an infilled rocking wall frame structure with rotational and translational friction devices [9]. Tsampras et al have experimentally investigated on deformable connection consisted of a friction device [10].…”