Shear testing of reinforced hybrid composite beams made of SFRELC and partial higher-strength conventional concrete

Abstract

Apart from the flexural performance of reinforced hybrid composite beams made of SFRELC (steel fiber reinforced expanded-shale lightweight concrete) and partial higher-strength conventional concrete, the shear properties are also essential to be understood for reliable application. To bridge this gap, sixteen reinforced hybrid composite beams compared with two reinforced SFRELC beams and two reinforced conventional concrete beams were experimentally studied under four-point test in this paper. The grades of SFRELC and partial conventional concrete were 40 MPa and 50 MPa respectively in cubic compressive strength. The composite depth ratio of conventional concrete to SFRELC varied from 0.3 to 0.5, the shear-span to depth ratio ranged from 1.5 to 3.0, and the volume fraction of steel fiber changed from 0.8% to 1.6%. The shear-cracking resistance, shear crack width, mid-span deflection and shear capacity of test beams were measured, and the crack distribution and failure modes were observed. Results indicate that the composition of SFRELC with higher-strength of conventional concrete confirmed a beneficial effect on the shear-cracking resistance and the shear capacity of reinforced hybrid composite beams. The interface of conventional concrete and SFRELC bonded well without any slip. The shear performance was slightly influenced by the composite depth ratio, and similar to reinforced SFRELC or conventional concrete beams with a varying of the shear-span to depth ratio and the volume fraction of steel fiber. Based on the test results, the tensile strength of SFRELC is used to predict the shear-cracking force of reinforced hybrid composite beams, while the equivalent tensile strength considering the combination of SFRELC and conventional concrete is used to calculate the shear capacity of reinforced hybrid composite beams. Finally, the design method is discussed for the shear capacity with the control of shear crack width of reinforced hybrid composite beams.