Seismic performance of a low-damage rocking column base joint along weak axis

Abstract

This paper presents an experimental and analytical study on seismic performance of a low-damage rocking column base joint equipped with an asymmetric friction connection (AFC). Cyclic loading tests were conducted along weak axis of the column, including INITIAL, AFTERSHOCK and REPAIR cases. Compared with the INITIAL case, the joint exhibited a 2.5% decrease in average moment resistance and a 24.9% decrease in rotational stiffness in the AFTERSHOCK case without any repair taken. By re-installing and tightening the AFC bolts, the moment resistance was completely restored and the rotational stiffness could reach 84.1% of the INITIAL case, achieving resilience and reparability of the joint. Internal forces of the column were effectively limited by frictional sliding of the AFC, and the maximum local equivalent plastic strain at the column base was only 1.0% at a drift ratio of 3%. Axial force, as the main source of restoring forces, provides a favorable tendency for self-centering of the joint. In addition, a finite element (FE) model was developed to quantitatively evaluate damage and sliding behaviors of the joint, and the low-damage characteristics were verified. Finally, a simplified analytical model was proposed to guide the design of this low-damage joint.