Experimental study on mechanical behavior of external prestressed FRP reinforced concrete beams

Abstract

This study proposes to investigate the failure characteristics and load-bearing performance of external prestressed composite reinforced concrete beams by conducting a three-point loading test on 12 full FRP reinforced concrete beams. These external prestressed concrete beams were reinforced with carbon fiber reinforced polymer(CFRP), while the stress reinforcement and stirrup were made of glass fiber reinforced polymer(GFRP). Specifically, the study compares the impact of prestress level, shear span ratio, and concrete type on the bearing capacity of GFRP reinforced concrete beams. derives an expression for flexural bearing capacity to account for the effect of stress increment of prestressed tendons, and is verified by experimental results. The test results indicate that the failure of non-prestressed FRP reinforced concrete beams is primarily governed by deformation, whereas applying prestress can shift the failure mode from deformation control to bearing capacity control. The mid-span deflection of the concrete beam is directly proportional to the increase in prestress. The bearing capacity of FRP beams decreases with an increase in shear span ratio, with particularly significant effect on cracking load. The effect of concrete type on the cracking load of prestressed beams surpasses its impact on the ultimate load, while it exerts minimal influence on cracking and ultimate load of non-prestressed beams. The calculated results for the bearing capacity of prestressed FRP reinforced concrete beams derived in this study align well with the measured values.

Keywords

• external prestress
• frp bars
• bearing capacity limit state
• deformation
• prestress level