Shear lag effect of composite cable-stayed bridges under dead and live loads

Abstract

The modern composite cable-stayed bridge always has a wider deck, and the slab has an obvious shear lag effect. At the operation stage, internal forces distribution of the composite girder under live loads differs from that under dead loads only. It is essential to investigate the shear lag of the main beam under dead and live loads. Then, in-situ tests under truck loads were carried out on Xia Zhang Bridge. Considering the superposition of axial forces, a simplified method is proposed to evaluate the effective width. The finite element models (FEMs) of the full bridge using solid shell elements under dead and live loads were established. The longitudinal distribution of the effective widths for concrete slabs under different loading positions and loading forms was obtained. Furthermore, the full-scale variable parameter analysis considering the effects of span lengths and deck widths was conducted by FEMs. The numerical results show that the composite girder segments at the location of the bridge tower and the loading position need to be concerned for shear lag analysis. A generalised verification for a cable-stayed bridge was made, and compared results show that simplified methods can calculate the normal stresses in slabs more accurately than Eurocode 4.