Experimental study on shear behavior of reinforced concrete deep beams with high-strength bars under uniform load

Abstract

This study aimed to investigate the shear capacity performance for five deep beams with reinforced high strength concrete under uniform load to enable a better understanding of the effects of longitudinal reinforcement ratio and vertical stirrup ratio. The shear behavior test was completed by simulating uniform loading with eight points of concentrated loading. The dimension of five test specimens is 1600 mm × 200 mm × 600 mm. The longitudinal reinforcement ratio is set to 0.67%, 1.05%, 1.27%, and the vertical stirrup ratio is taken to be 0.25%, 0.33%, 0.5%. Through measuring the strain of steel bar, the strain of concrete, and the deflection of mid-span, the characteristics of the full process of shear capacity, the failure mode and the load–deflection deformation curve were examined. Based on this test, a 3D finite element model is established to verify the reliability of the test results. In addition, the calculation formula in the Code for Design of Concrete Structures (GB50010-2010) is used to calculate the shear behavior of deep beams, and the finite element calculation results and the code calculation results are compared with the test values. The results show that three typical failures mainly occur in deep concrete beams under uniform load: diagonal-compression failure, splitting failure, and local-compression failure. With the increase of longitudinal reinforcement ratio, the ultimate bearing capacity gradually increases. The increase of vertical stirrup ratio is helpful to improve the shear behavior of deep beams and inhibit the development of diagonal cracks. The 3D finite element model calculation results are close to the experimental values, and the finite element model can reasonably reflect the stress mechanism of deep beam members. Finally, the average value of ultimate bearing capacity of the experimental values compared with the code (GB50010-2010) calculation results is 2.208, and the results are on the conservative side. The obtained results show the code (GB50010-2010) has sufficient safety reserves.