Strong axis low-damage performance of rocking column-base joints with asymmetric friction connections

Abstract

This paper presents an experimental and analytical study on the low-damage performance of a steel rocking column-base joint equipped with an asymmetric friction connection (AFC). The AFC is located at the web of the column base with a frictional sliding surface parallel to the weak axis of the column. Cyclic tests with and without axial forces were carried out along strong axis of the column, including initial, aftershock and repair cases. It was found that in the absence of axial force, the column was completely uplifted after unloading, while in the presence of axial force, the joint could be self-centered. The presence of axial force provided a good tendency for the self-centering capacity of the joint. Resilience of the joint is achieved by simply re-tightening the bolts, and its seismic performance can be well matched to the initial run without loss of strength and stiffness. A finite element model was developed to investigate the stress distribution and frictional sliding behavior of the joint. The low-damage characteristics exhibited by the joint were verified at a high drift ratio of 3%. Finally, a simplified flag-shaped analytical model was proposed to predict the mechanical behavior of this type of column-base joint.