Research On The Shear Lag Effect Of Thin-Walled Box Girder

Shear lag phenomena or the nonuniform distribution of bending stress across wide flanges of beam cross section have long been recognized and studied.First studies were mainly concerned with stiffen beam of I shape in aviation engineering,while later concerned with civil engineering. Some research outcomes about shear lag problems were attained and part of project problems were solved during the twenty years.with the development of communication there are still many problems which need farther research.In this dissertation,shear lag effect is studied.The main contents are the followings.1.A general potential energy equation is derived according to the principle of minimum potential energy and a set of differential equations with different boundary conditions are derived according to variational principle method considering the deformation properties and longitudinal displacement functions of constant depth box girders.The shear lag effect of simple supported beam will be studied with an exaraple.The method of substitute variable is applied to study the shear lag effect of continuous box girders with variable depth.2. The negative shear lag effect of the cantilever and continuous girders is studied and the parameters which influence the shear lag effect is analysed.3.Combining with the experiment of Yibin Zhongba Jinshajiang cable-stayed bridge concrete model,this dissertation analyses the shear lag effect of the cable-stayed bridge.By the work of this dissertation ,more safer and more reasonable design and analysis method for box gerder have been offered.