Research On Shear Lag Effect For Straight Box Girder Jointless Bridges

Jointless bridges are becoming more popular and were used widely because of many advantages and little limitations.A lot of reaearches had been done on shear lag effect for bridges with joint by many specialists and scholars.Many important conclusion had been drawed such as, for negative shear lag ,the displacement of border is interior factorand the form of outside load is exterior foctor.Furthermore,for jointless bridges,because of the change of border displacement and taking pile-soil effect into account and inherent structure traits,the internal force state is different in contrast to bridges with joint.As a result,the theories on shear lag for bridges with joint are incapable to reflect the actual state of shear lag for jointless bridges.So researches on shear lag and finding out the appropriate finite element calculate methods are essential to popularize jointless bridges. The main contents of the paper are described as follows: 1) In this paper,with taking pile-soil effect into account, an appropriate method of setting up finite element model of jointless bridges with integral abutment is found out in order to set up a representative single-box-single-cell box girder model which is used to carry out static calculation.And then in contrast to a simple-supported box girder with the same forms of loads and section,the particular rules on shear lag of jointless bridges are got.At the same time ,many calculation methods on shear lag are listed in this paper to further the study on shear lag effect for jointless bridges. 2) A polymethyl methacrylate model test is performed to validate the finite element model and the conclusions made in first step. 3) Parameters of influencing shear lag effect for jointless bridges are discussed,which include boundary conditions of box girder,forms of loads,parameters of box girder.And the main influencing parameters were picked up. 4) A chart about shear lag factors for straight box girder jointless bridges is presented in this paper, which is developed by taking into account the main parameters based on engineering practice.