FAILURE MECHANISM AND STRENGTH CALCULATION OF COMPOSITE SHEAR STEEL FIBER RECYCLED CONCRETE

To investigate the mechanical behavior of steel fiber recycled concrete under a composite shear condition, 102 standard cubic specimens were designed for the composite shear test with a substitution rate, with normal stress and with steel fiber content as changing parameters. The failure modes of steel fiber recycled concrete under direct shear and compression shear were observed, and the shear stress-displacement curves of the whole process were obtained. The influences of substitution rate, of normal stress and, of steel fiber content on the shear strength and on the peak displacement of steel fiber recycled concrete were analyzed in depth. The research shows that shear strength increases with the increase of normal stress. The shear strength of recycled concrete with steel fiber content of 0% decreases with the increase of substitution rate. The shear strength of recycled concrete with steel fiber content of 1% increases first and then decreases with the increase of substitution rate. The average shear strength of steel fiber recycled concrete with the content of 1% increases by 10.77% compared with the steel fiber recycled concrete with the content of 0%. The shear strength formula is presented, and the calculated results agree well with the test results.