Experimental and analytical shear evaluation of concrete beams reinforced with glass fiber reinforced polymers bars

Abstract

This paper presents an experimental and analytical study on the shear behavior of concrete beams reinforced with lab produced glass fiber reinforced polymers (GFRP) bars and stirrups. The bars and stirrups are manufactured by double parts die mold using local resources raw materials at lab. A total of ten beams measuring 120mm wide, 300mm deep and 1550mm long were casted and tested up to failure under four-point load. The main parameters were concrete compressive strength and the vertical GFRP web reinforcement ratio in the form of the number of GFRP stirrups (without stirrups and with 8 @ 215, 8 @ 150 and 8 @ 100 stirrups). The mid-span deflection, inclined crack load and GFRP reinforcement bars and stirrups strains of the tested beams were recorded and compared. The test results revealed that the shear capacity increasing by 41% and 82% of the shear carrying capacity of beam without stirrups by using web GFRP reinforcement of 8 @ 215 and 8 @ 100 respectively. The shear capacity increased by 49% and 104% as the concrete compressive strength increased from 25MPa to 45MPa and 70MPa respectively. The maximum value of measured strain in GFRP stirrups reached 0.0095. New approach to calculate FRP stirrups shear strength was proposed and verified throughout an assessment of experimental results of current study and previous works. The shear capacities of the tested specimens were calculated using the strut and tie models (STM) and non-linear finite element analysis (NLFEA). The average ratio of experimental shear capacity to calculated (Vexp/Vpred) using NLFEA and STM were 1.2 and 0.9 respectively.