Experimental study on the tensile-shear coupling performance of fully prefabricated assembled floor slabs with UHPC wet connections

The performance of UHPC wet connections between prefabricated slabs directly affects the overall integrity and resistance performance of the floor system under lateral seismic loads. The core factors are the transmission and failure mechanisms under tensile load, shear load and tensile-shear coupling load. To clarify the mechanical properties of UHPC wet connections, four tensile tests, seven shear tests, and nine tensile-shear coupling tests were conducted to investigate the effects of steel bar overlap length, shear key construction, and loading mode on the failure mechanism of wet connections. The load-displacement curves, failure mode, and strain development curves of specimens corresponding to different parameters were analyzed. The research results indicated that the longitudinal tensile strength and lateral shear strength of the steel bars at the UHPC wet connection could be fully used when the overlapping length of steel bars reached 12 times the diameter. The application of UHPC shear keys could significantly improve the shear resistance of wet connections: even if the steel bar overlap length was lower than 12 times the diameter, the use of shear keys could ensure that the shear resistance of wet connections was greater than that of the prefabricated slabs. In addition, the shear performance of steel bars and shear keys under the tensile- shear coupling load significantly decreased, the larger the level of tensile load, the worse the shear performance of wet connections. Adequate overlap length of steel bars and the application of shear keys were two key factors to ensure that the wet connections were not inferior to the prefabricated slabs under complex load conditions.