Novel design method for reinforced concrete decks in composite girders considering compressive membrane action

The deck slab in composite box girder is laterally and rotationally restrained, and the compressive membrane action (CMA) improves the stiffness and capacity of the slab under the vertical load. However, a rational design method for the slab in composite box girder is still lacking. The purpose of this paper is to establish theoretical models to predict the behaviors of the laterally and rotationally restrained slab at ultimate and serviceability limit states. First, a nonlinear whole process mechanism analysis of a laterally and rotationally restrained deck slab is conducted. Compared with previous studies, this research considers additional factors such as the rotational restraint stiffness, the lateral restraint eccentricity, two lateral restraints and the thickness variation of the deck slab. Subsequently, key performance indicators for the ultimate and serviceability limit states are proposed and investigated by a comprehensive parametric study. The parametric analyses results indicate the appreciable impacts of the rotational restraint stiffness, lateral restraint eccentricity and thickness variation of the deck slab. Furthermore, simplified formulas of the key performance indicators are obtained by regression. Finally, based on the mechanism analysis and the parametric study, design methods for predicting the load capacity and the load corresponding to the control crack width of the deck slab are proposed and then validated by the finite element analysis and test results.