Seismic behavior of self-centering column base with replaceable stiffener angle steels

Abstract

An innovative performance-recoverable self-centering column base with replaceable stiffener angle steels was proposed to achieve the restoration of structural functionality after earthquake. The column base was assembled using a steel connector and a web friction device, post tensioned strands and stiffener angle steels were also employed to provide self-centering ability and replaceable ability respectively. Quasi-static tests were conducted on six group specimens to explore the seismic behavior of this kind column base. And the ability of resisting aftershocks, the effects of replacing stiffener angle steels as well as replacing stiffener angle steels accompanied by re-tensioning post tensioned strands after earthquake on the recovery of seismic performance under different axial compression ratio for this kind column base were also investigated. During the tests, the column base performed an excellent seismic behavior, and the damage was concentrated in stiffener angle steels. The test results indicated that the proposed column base had satisfactory seismic redundancy, which still presented a good load carrying capacity after being damaged by an earthquake; Replacing stiffener angle steels could significantly recover the seismic performance, which was a fast low-cost post-earthquake repair method with high cost performance; Replacing stiffener angle steels accompanied by re-tensioning post tensioned strands could recover the seismic performance to the level before earthquake, which was a perfect post-earthquake repair method; Under the larger axial compression ratio of 0.3, the column base showed higher bearing capacity, initial stiffness and energy dissipation, but the loss of prestress was more severe and the self-centering ability was relatively poor. A novel design philosophy of “elastic under minor earthquake, self-centering under moderate earthquake and replaceable under major earthquake” could also be realized well by proper design. A moment calculation method which could distinguish the gap opening was also proposed, and the calculated results agreed well with the experimental results.