Analytical model and design method of corrugated steel-concrete composite girders under torsion

The torsional effect of prestressed corrugated steel-concrete composite girders (PCSCCG) is more prominent due to its low torsional stiffness, which is therefore crucial to be clarified for safe design. This paper proposed a theoretical model based on the combined actions softened-membrane model (CA-SMM) to predict the torsional response of PCSCCG. The equilibrium, compatibility and constitutive equations were established to consider the characteristics of corrugated steel webs (CSW) and prestressing effect, where a reasonable shear strain assumption was presented to determine the force behavior of concrete slabs and CSW, and the thickness of shear flow in concrete slabs was corrected. An optimized algorithm using the gradient descent method was established to improve the insufficiency and stability. Based on this, a simplified design method was proposed to rapidly evaluate the torque and twist of PCSCCG. Finally, the feasibility of the proposed model and simplified design method was verified by available tests. The superiority of the analytical model in predicting the full torsional performance of PCSCCG was proved, and the reasonability and simplicity of the simplified method in capturing the cracking, yield, and ultimate torques and twists were observed.