Composite Action of Concrete-Filled Rectangular GFRP Tubes

Abstract

This paper investigates the composite action and performance of rectangular concrete-filled glass fiber–reinforced polymer (GFRP) tubes in four-point bending. The study compares the performance of three different concrete-filled beam configurations with different levels of adhesive bonding of the concrete core to the GFRP tube. The three different configurations include (1) unbonded, (2) bonding of the flanges, and (3) bonding of the flanges and webs. The results show low composite action for the unbonded beam configuration up to full composite action for the completely bonded beam configuration. An analytical study is presented to provide insight into the failure mechanism for the fully bonded beam configuration and to predict ultimate capacity. For evaluation, the stiffness and strength of the fully bonded concrete-filled GFRP tube considered in this study is compared with a conventional steel reinforced concrete beam, concrete-filled steel tube, and concrete-filled GFRP tube with carbon FRP (CFRP) tension flange of the same dimensions.