Experimental and numerical study on tensile performance of GFRP bar reinforced UHPC members

Glass fiber reinforced polymer (GFRP) bar reinforced ultra-high performance concrete (UHPC) (GFRP-UHPC) members’ tensile performance should be significantly different from that of steel-UHPC members due to differences between GFRP and steel bars in mechanical and bond properties. In this paper, six dog-bone shaped specimens with different types of reinforcement materials, rebar diameters, and quantities of rebars were fabricated and tested under axial tension, and their failure modes, load-displacement curves, and cracking behavior were recorded and investigated. Furthermore, an extensive nonlinear finite element analysis considering the bond behavior between rebars and UHPC was conducted. Finally, formulas were proposed to predict the tensile stiffness and ultimate tensile capacity of GFRP-UHPC members. Results confirmed that bond shear strength (τcs) and stiffness (K) of the GFRP and UHPC interface were the key factors that affected GFRP-UHPC members’ tensile performance: τcs mainly determined the failure mode; increasing K and the reinforcement ratio can improve the post-cracking stiffness and obtain tension hardening behavior; the wedging effect caused the post-cracking curve of the tension member in bond failure mode re-ascend periodically. The proposed formulas could produce accurate and safe predictions after comparing predicted results with experimental and simulation results. This study provides the underlying insights needed to guide the design of GFRP-UHPC members.