In this study, the compressive membrane action (CMA) in the deck slab of I-steel–concrete composite bridges was investigated. Nine static loading tests were conducted, and finite-element (FE) analyses were developed. The FE models were validated by test results and used to conduct parametric studies. The investigation examined the effects of the deck slab dimensions, transverse connection form, restraint conditions, and loading conditions. Through analysis of load–deflection curves, slab end rotation, concrete cracking, bolt strain, and slab lateral expansion, the mechanism and factors influencing the formation of CMA in the deck slab were explored. The results demonstrate that the deconstructable bolted connectors effectively transferred the interfacial shear force, and the CMA effect enhanced the ultimate load capacity by 33%–256% compared to the theoretical bending capacity. The most significant improvement was observed in deck slabs characterized by lower reinforcement ratios, larger thickness, weaker rotational restraint, and two-point loading. Specifically, the increase attributed to the CMA effect in slabs with weak rotational restraint was 4.4–6.4 times higher than that in slabs with strong rotational restraint. To estimate the load capacity of deck slabs considering the CMA effect, formulas for the lateral and rotational restraint stiffness are proposed based on the test and FE analysis results. The comparison of test results demonstrates the effectiveness of the proposed formulas.
Zhu et al. (Fri,) studied this question.