Experimental and numerical investigations on flexural performance of ultra-high-performance concrete (UHPC) beams with wet joints

Ultra-high-performance concrete (UHPC) wet joint beams with inverted trapezoidal keyed (ITK) joints were tested. A nonlinear finite-element model (FEM) for simulating the mechanical behavior of UHPC wet joint beams was also established. Parametric studies of the UHPC wet joint beams were conducted using the verified FEM analyses. The results indicated that the first visual crack and maximum crack width of the UHPC wet joint beams appeared at the wet joints. Improvements in the reinforcement ratio could significantly limit crack propagation and increase the flexural capacity of UHPC wet joint beams. The initial flexural stiffness of the UHPC beam was insignificantly affected by the wet joints, whereas the flexural stiffness degradation of the UHPC wet joint beams due to cracks was faster than that of the monolithic beam. The joint shape had a significant influence on the flexural performance of the UHPC wet joint beams. Among the keyed joints, the ITK joint exhibited the best flexural performance. The flexural performance of the UHPC wet joint beams with small-sized ITK joints was superior to that of large-sized joints. The difference in the flexural capacity between the UHPC wet joint beams and monolithic beams decreased as the reinforcement ratio increased.