Cyclic compressive behavior and load-strain model of FRP-concrete double tube composite columns

A novel fiber-reinforced polymer (FRP)-concrete double tube composite column, consisting of an outer filament winding FRP tube, an inner pultruded FRP tube and infilled core concrete and ring concrete, has been proposed and experimentally investigated under monotonic compression by the authors. It exhibited obviously improved deformability than the traditional FRP-confined concrete columns. In this study, cyclic compression tests were conducted on the composite column to examine its structural behavior under cyclic loadings. Effects of different outer and inner FRP tube thicknesses and ring concrete types were investigated. Failure modes, cyclic load- strain responses and hoop strain behavior were presented and analyzed. Cyclic load-strain model, including the envelope model, unloading and reloading models, plastic strain equation and stress deterioration equation, was proposed to predict the cyclic compressive behavior of the FRP-concrete double tube composite columns. The proposed model was verified against the test results and exhibited good performance.

Automated summary

This study proposed and experimentally investigated a novel fiber-reinforced polymer (FRP)-concrete double tube composite column. It exhibited improved deformability compared to traditional FRP-confined concrete columns. Cyclic compression tests were conducted to examine its structural behavior under cyclic loadings. Different thicknesses of outer and inner FRP tubes and types of ring concrete were investigated, and a cyclic load-strain model was proposed and verified against the test results.