Flexural Crack Performance of the Steel–GFRP Strips–UHPC Composite Deck Structure

Abstract Concrete cracking is one of the important factors affecting the safety and durability of composite bridge structures. While the existing crack width calculation methods cannot accurately predict the crack width of ultrahigh-performance concrete (UHPC), this paper aims to investigate flexural crack performance (e.g., failure mode, crack width, and crack spacing) of an innovative composite deck structure comprising an I-steel beam and glass fiber‒reinforced polymer (GFRP) strips‒UHPC composite deck. Three GFRP‒UHPC composite slabs and two steel‒GFRP strips‒UHPC composite beams are designed to explore the cracking behaviors in transverse and longitudinal directions, respectively. The effects of reinforcement ratio and the steel fiber content on flexural cracking behavior are analyzed. The results showed that increasing the reinforcement ratio restricts the formation and growth of cracks and reduces the crack width and average crack spacing in the UHPC plate. However, the impact of steel fiber content is small. The steel‒GFRP strips‒UHPC composite beams fail owing to the yield of the I-steel beam and longitudinal reinforcement bar in the UHPC plate, while the GFRP‒UHPC composite slabs collapse as a result of the yield of reinforcement bar in the UHPC plate. Based on the existing test results, the formulas are proposed to estimate the reinforcement stresses and the maximum crack width in the steel‒GFRP strips‒UHPC composite deck structure, and the findings have indicated good agreement with the measured ones.