Mechanical Character And Experimental Research On Shear Lag Effect In Cantilevered Composite Box-girder With Corrugated Webs

Composite box-girder with corrugated webs comes from the idea that reduces the thickness of webs, lightens the weight of box-girder,shortens the pre-stressed steel. In the past 20 years, some research about box-girder with corrugated webs were obtained and part of practical problems were solved in some country. But some new problems about box-girder with corrugated webs appear continuously, even some of them don't start and need further research. Now the thesis is based on one scientific fund project ,and some research and experiments are studied about cantilevered composite box-girder with corrugated webs. The main contents are listed as follows:1. Under a balanced or eccentric load test at the elastic stage, the strain with plane section assumption distribution along depth basically is concluded,and the characteristic resistance of bending moment and shear is analyzed.2.As to the approach to shear lag effect in cantilevered composite box-girder with corrugated webs of constant depth under a load, a set of equations with different boundary conditions are derived in response to the longitudinal displacement functions with the calculating method of wraping function,and the principle of minimum potential energy considering the energy deformation properties. As for the variable depth cantilevered box-girder,the equations are derived according to the differential equations of the constant depth cantilevered box-girder. Then calculating formulas for shear lag effect in cantilevered composite box-girder with corrugated webs of constant depth and variable depth are deduced.3. Comparing to the data analyses of load test, FEM and calculation,the results are accordant. Based on it ,the variation studies of shear lag effect in cantilevered composite box-girder with corrugated webs are generalized and different main parameters are analyzed, which are put forward for parametric calculation of shear lag effect in cantilevered composite box-girder with corrugated webs.4.Under a uniformly-distributed load, the negative shear lag effect of the cantilever girders appears due to the symbolic change of the additional bending moment caused by shear lag effect. But the region of negative shear lag is different between composite box-girder with corrugated webs and box-girder,and the longitudinal distribute rules of negative shear lag effect are analyzed.