Shear lag effect of composite girders in cable-stayed bridges under dead loads

Abstract

The shear lag effect is a common phenomenon among civil infrastructures, which is also a critical issue for composite girders. For composite girders in large-span cable-stayed bridges, there is a large proportion of internal forces caused by dead loads, and the shear lag effect of the concrete slab under dead loads is significant. To investigate the normal stress distribution at the construction and service stages, systematic in-situ stress monitoring of composite girders was performed on a cable-stayed bridge under dead loads. Then, the finite element models were built for numerical modeling. The theoretical analysis model was proposed to evaluate the shear lag effect of composite cable-stayed bridges under dead load. Then the law of the stress ratio and the shear lag effect was analyzed by contrasting the test data and simulation results. Meanwhile, the calibrated FE models were used to do the full-scale parametric analysis of the factors including span length, slab width, and cable spacing. The results show that the main girder segment near the bridge tower and the mid-span are critical sections at the construction and service stages for analyzing the shear lag effect. The cable spacing and slab width are the main factors affecting the shear lag effect under dead loads. The effective width coefficients are positively correlated with the stress ratio.