Numerical Study on Performance of Single-Keyed Dry Joint of Ultra-High Performance Concrete (UHPC) Under Combined Shear and Torsion Load

Under the vehicle load, segment joints are subjected to coupling effects of bending, shear, and torsion, while for dry joints, they are mainly subjected to a combination of shear and torsion, making them more prone to failure. In this study, to investigate the performance of single-keyed dry joint of ultra-high performance concrete (UHPC) under combined shear and torsion load, finite element model (FEM) was carried out considering the effect of confining pressure. Then AASHTO code equations was chosen to predict the shear-torsion capacity of UHPC single-keyed dry joints. The results of FEM indicated that the increase of confining pressure can effectively improve the shear-torsional load capacity of the dry joints. Whereas the increase of confining pressure has little effect on the improvement of stiffness. From the failure mode of specimens, the specimens are damaged in the root of the shear key when confining pressure is less than 18 MPa. However, in view of the high confining pressure (when the confining pressure is greater than 18 MPa), the damaged surface of the specimen changes from the root of the male key to the feminine key. In addition, the evolution of AASHTO equation shows that the AASHTO code equations were overestimated the ultimate capacities of UHPC single-keyed dry joints under shear-torsion load.