Effects of the Tensile and Shear Properties of Bolts on the Shear Properties of Bolted Rock Joints

The mechanical properties of bolts are important factors affecting the shear behavior of bolted joints. In this study, tensile and pure shear tests were conducted on five kinds of bolts made from different materials to measure their tensile and shear parameters. Direct shear tests were conducted to analyze the effects of tensile and shear strength parameters on the shear behavior of bolted joints. The test results showed that the mechanical properties of bolts made from different materials were clearly different and that these differences mainly affected the plastic deformation stage of the bolted joints. The larger the bolt elongation was, the larger the joint shear displacement at bolt failure. The tensile and shear strengths of the bolts were positively correlated with the shear strength of the bolted joints. According to the standard regression analysis, the bolt shear strength had a greater influence than the bolt tensile strength on the bolt contributions when the bolts were perpendicular to the joint surface. Based on the empirical equation for the bolt contribution proposed by Spang, the maximum shear loads in the pure shear test were introduced, and a new equation was established to predict the contributions of bolts. The prediction results obtained using the modified equation were in good agreement with the experimental results.