Research On Shear Lag Effect In Box Girder Of Cable-Stayed Bridge With Single Tower And Single Cable Plane

Based on the previous analytical theories and methods of calculation of shear lag effect, the bar simulation method and spatial finite element method are presented to study shear lag effect in box girder of cable-stayed bridge with single tower and single cable plane, according to it under combined axial and lateral loading. On the background of one typical cable-stayed bridge with single tower and single cable plane, spatial finite element method was adopted to research shear lag effect in multi-cell box girder of such kind of bridge, and the influence of some factors such as prestress, the transverse acting location of external load, was analyzed. Through the rearch, some conclusions were gained as bellow: as well as spatial finite element method, bar simulation method can analyse the shear lag effect in multi-cell box girder of cable-stayed bridge with single tower and single cable plane accurately; if areas of substitute stringers were calculated accurately, three bar method could also evaluate its shear lag effect approximately, but it has limitation on forecasting shear lag effect in multi-cell box section; under dead and live loads, the shear lag effect in box girder of cable-stayed bridge with single tower and single cable plane is comparatively complex, and the shear lag phenomenon in the top or bottom flange plate at positions adjacent to different web plates is variational; the shear lag phenomenon in section of box girder adjacent to root of tower is comparatively severe, but it decline rapidly in sections near root of tower; when internal forces of main girder of bridge analyzed under live load designed were calculated, an amplificatory coefficient 1.20 should be considered; the transverse acting location of external load has obvious influence on the shear lag effect in box girder of cable-stayed bridge with single tower and single cable plane; the exertion of prestress improve working behavior of main girder of cable-stayed bridge, but has little influence on distribution of longitudinal stress in main girder; under uniformly distributed load, the disposal of cables has obvious influence on shear lag effect in bottom flange plate of box girder of single tower cable-stayed bridge, but disposal of tower has little influence on it; multi-cell box girder, which has large torsion stiffness, and system ,in which tower, girder, and pier are fixed, make up for insufficiency of torsion stiffener of main gird caused by single cable plane.