Experimental Study on Basic Performances of Reinforced UHPC Bridge Deck with Coarse Aggregates

Abstract

In order to reduce the self-weight of conventional steel-concrete composite girders and to improve the crack-resisting behavior of normal strength concrete (NC) bridge decks for long-span cable-stayed bridges, an innovative steel–ultrahigh performance concrete (UHPC) composite girder was proposed. Coarse aggregates (CA) were added to UHPC to control shrinkage and cost. On the basis of the Fifth Nanjing Yangtze River Bridge (FNYRB), a 2 × 600 m cable-stayed bridge in China, a series of experimental tests was conducted. The studies aimed to reveal the material properties of UHPC with and without CA and the static and fatigue flexural performances of the reinforced UHPC deck with CA. The test results implied that the UHPC with CA had compressive strength and flexural strength comparable to UHPC without CA, but the former exhibited much lower shrinkage strains under the natural curing condition. The static bending test results showed that the steel fibers and steel reinforcement bars could effectively control the propagation of cracks in UHPC. The average nominal cracking strength of the UHPC bridge deck specimens was 13.8 MPa, about 1.97 times the maximum tensile stress in the design requirement of the FNYRB under serviceable design loads. Further, the fatigue bending test results demonstrated that the cracks in UHPC propagated very slowly under cyclic tensile stresses, and the residual flexural loads were only 7.2% and 10.9% lower than the ultimate loads obtained for specimens free from the fatigue loading processes. Thus, the current study verified the safety of applying UHPC with CA to long-span cable-stayed bridges.