Flexural behavior of ultra-high-performance concrete beams with various types of rebar

This study describes the behavior of ultra-high-performance-concrete (UHPC) beams with GFRP and steel reinforcements. The experimental results were presented and the influences of parameters, including reinforcement ratio and longitudinal rebar type on the flexural performance of the UHPC beams, were investigated and discussed. The test results show that increasing the amount of GFRP reinforcements results in the enhancement of their flexural behavior, including load bearing capacity, post-cracking stiffness, and deformation capacity. The ductility decreased when greater GFRP reinforcements were designed. Compared to steel reinforced beams, the UHPC beams with GFRP rebars performed more rapid stiffness degradation and crack width development. The use of steel reinforcements by replacing GFRP rebars in the beam contributed to the improvement of some flexural behavior, including cracking load, post-cracking behavior, displacement, and ductility. The bond strength and ability to retard crack development between GFRP rebars and UHPC are worse than that between steel rebars and UHPC. The design equations recommended by the design codes showed that existing codes may over-estimate the ultimate flexural capacity and crack width of the GFRP-UHPC beams. The increasement of GFRP reinforcement ratio will cause the calculated displacement based on the codes less than that obtained from experiment.