Behavior of GFRP-concrete double tube composite columns

Abstract

A novel glass fiber-reinforced polymer (GFRP) — concrete double tube composite column, which consists of an outer filament winding GFRP tube, an inner pultruded GFRP tube and infilled core concrete and ring concrete, is proposed in this study. A total of 20 specimens were tested to investigate the structural behavior of the composite column. High strength concrete (HSC) was used as the core concrete filled in the inner pultruded GFRP tube, while engineered cementitious composite (ECC) or normal concrete (NC) with medium compressive strength was used as the ring concrete. Different outer and inner GFRP tube thicknesses were considered. Test results reveal that overall performance of the GFRP-concrete double tube composite columns, especially the deformability, is effectively enhanced in comparison to the corresponding normal GFRP-confined HSC columns. Axial load–strain responses and dilation behavior of the composite column were carefully analyzed. Based on the test results, equations are developed to predict the ultimate load carrying capacity and ultimate axial strain for the proposed GFRP-concrete double tube composite column.