Cyclic behavior of recycled-lump-concrete-filled GFRP tubular columns: Experimental investigation and numerical modeling

Abstract

A fiber-reinforced polymer (FRP) tube offers the advantages of lightweight formwork, external confinement, and non-corrosive reinforcement for recycled lump concrete (RLC), creating an attractive opportunity for structural applications of this green material. While prior research has predominantly focused on the axial compressive behavior of RLC-filled FRP tubular columns, this study addresses the implications of using such members in seismic areas. Six large-scale RLC-filled Glass FRP (GFRP) tubular columns were tested under constant axial compression and quasi-static reversed lateral loading to examine the impact of crucial parameters on their cyclic behavior. Additionally, the study discusses the numerical modeling of such columns using a fiber beam element approach. The findings indicate that the replacement rate of recycled lumps (<33%) has limited impact on the cyclic behavior of the columns. Reducing the GFRP tube thickness and simultaneously adding a minimum amount of longitudinal steel reinforcement can improve the hysteretic response. An off-axis tube with a fiber orientation close to 50° appears more suitable for structural use compared to 80°. Moreover, even with a tube diameter-to-thickness ratio of 100, the columns still meet the code requirement for lateral drift limit of flexural-dominated members. Overall, the study contributes to instilling confidence in the scaling-up applications of RLC-filled GFRP tubular columns in earthquake-prone areas.