Bracket Cast Cable-stayed Bridge Main Beam Shear Lag Effect Analysis

Based on traditional theories and ideas that were used to analyze shear lag in trough girder effectively by predecessors, a displacement model of shear lag in II-sectional beams is introduced in this paper. A differential constrain equation of shear lag is educed, which is based upon E.Reissener's Energy Variation Principle. A formula of shear lag is obtained in different boundary conditions.According to mechanics properties of a cable-stayed bridge, the bridge may be separated into a lot of single span continuous beams with elastic supporting subjected to axial load. And then, the continuous beams are dismembered into simple beams at reverse bend points in the bend moment figure. At this time, shear lag can be calculated in simple-beams on basis of Small Deflection Theory and Superposition Principle.In this paper, De-zhou Xinhe River Bridge is selected as an example to analyze shear lag in final state of bridge and in construction state by the finite element software -ANSYS. The computed result shows that severe shear lag locally exists in cable-stayed bridge. Such as in cross-section of main beam. Effects of shear lag of girder-sectional beam in the cable-stayed bridge is related to supporting condition, varies along the span of bridge and is influenced under the inherent stress of main beam, the transverse slope and cross beam.