Research on Flexural Performance and Crack Width Calculation Method of Ultra-High Performance Concrete Link Slab

In order to resolve the cracking problem of reinforced concrete(RC)link slabs used in simply-supported girder bridges with continuous decks, the ultra-high performance concrete(UHPC)link slab with high tensile strength and strong crack resistance is proposed and the flexural performance of the UHPC link slab is studied. The experimental tests on the link slab specimens under bending were carried out to compare the load-midspan deflection curves, crack propagation, deflection distribution in the longitudinal direction, concrete strain and reinforcement strain of the UHPC and RC link slabs. The key design parameters of the UHPC link slab were analyzed by finite element method. Based on the measured data, the method to calculate the maximum crack width of the UHPC link slab was studied. The results indicate that the crack resistance and flexural stiffness of the UHPC link slab are better than those of the RC link slab. The utilization of UHPC link slab can lead to the reduction of the localized flexural strain of the link slab. The steel fibers in the UHPC link slab can restrict the crack propagation and help the concrete and reinforcement work together. The thickness of the UHPC link slab and the debonding layer also influence the ultimate bending moment of the UHPC link slab, either increasing the thickness of link slab or reducing the debonding layer thickness can improve the ultimate bending moment. By comparing different specifications or references, it is concluded that to calculate the bending-induced maximum crack width of the UHPC slab, the method to calculate the maximum crack width of the UHPC link slab in the steel-UHPC lightweight composite deck is also an alternative.