Shrinkage effect and mechanical performance of steel-ultra-high performance concrete composite deck under negative bending action

Abstract

Shrinkage effect can result in damages in steel-UHPC composite decks. And these damages may even cause mechanical performance degradations. The details are critical to deck design practice and evaluation theory establishment while not being clearly understood. In this study, static shrinkage monitoring and negative bending tests on two full-scale segmental composite deck specimens (D12 and D16) were sequentially conducted. 12-mm- and 16-mm-diameter reinforcements were respectively embedded in the specimens. Simulation and parametric analysis were executed as well for further understanding. The 90 days static shrinkage monitoring results showed the maximum induced compressive strains on reinforcements of D12 and D16 were 559 με and 328 με. The maximum compressive strains on steel deck plates were 80 με and 82 με. It indicated shrinkage effect cannot be ignored. The bending test results showed the UHPC tensile strain maximums were 1458 με and 1149 με in the two specimens when the maximum UHPC crack width was 0.10 mm. Moreover, the simulation analysis results also showed that the model with 90 days shrinkage effect had a 16% lower bending secant stiffness at the load level equivalent to allowable UHPC crack width. And the reduction increased to nearly 40% when the crack width reached 0.10 mm. In addition, the parametric analysis showed that a strain-hardening feature could be favorable to delay the UHPC damage evolution compared with a strain-softening one with relatively lower tensile strength. These results provided important support to the design practice of steel-UHPC composite decks.