Restoring force model of hollow prefabricated square pier with grouted sleeves connection and high-strength steel bars

Abstract

Seismic-performance investigation of piers under cyclic loading is based on the restoring force model (RFM). In this paper, the seismic performance of a hollow prefabricated square pier with grouted sleeve connections and high-strength steel bars was investigated; and a calculation method for its RFM was established. Based on the plane section assumption and the ideal elastic-plastic material assumption, the stress distribution of the pier's weak sections and the curvature of the pier body at different stress periods were analysed. The coordinates of the characteristic points of the pier's load–displacement curve were obtained. Next, the trilinear model of the pier's skeleton curve was obtained. The residual displacement of the pier under different loading displacements was calculated using a fitting equation for the unloading stiffness of the pier. Based on the principle of maximum point pointing, the loading and unloading paths of the pier under reciprocating loads were determined; and the RFM curve of the pier was finally established. This laid a foundation for the investigation of the pier's performance under reciprocating loads.