Experimental and numerical study on the tensile behaviours of wet joints in steel-UHPC composite decks using a novel tensile test setup

A composite deck system composed of ultrahigh performance concrete (UHPC) and an orthotropic steel deck has been proposed to solve fatigue cracking and corrosion problems in traditional orthotropic steel deck systems. In a prefabricated steel-UHPC composite deck system, a wet joint is usually formed between two adjacent prefabricated UHPC layers. The interface between the prefabricated UHPC layer and cast-in situ UHPC is defined as a wet joint. To investigate the tensile behaviours of the wet joint, a novel tensile specimen configuration simulating the wet joint was initially proposed. The effects of reinforcement diameter and embedment length were experimentally investigated. The test results revealed that increasing the embedment length could enhance the crack resistance at the wet joint, but the influence could be neglected when the embedment length is greater than 10 db (db = diameter of reinforcement). Based on tensile tests, three-dimensional FE models were developed to simulate the tensile behaviours of the wet joint, and their accuracy was confirmed by the test results. With the validated FE model, the effect of UHPC thickness on the tensile behaviours of wet joints was investigated. Finally, specific design parameters were recommended according to the test and numerical results.