Research On Transverse Distribution Coefficients Of Composite Box-Girder Bridge With Corrugated Steel Webs

Box girder has superior performance on the bending and torsion strength, corrugated steel webs replacing concrete web not only can reduce girder structure’s weight, but also improve the utilization of prestress. Composite box-girder with corrugated steel webs is widely used in the medium and small span beam bridge because of the mechanic advantages. Considering the construction, width and aesthetic property, multi box single cell section is common in bridges of mountain and urban. Given this, the paper has studied transverse distribution coefficients of bridges of multi box single cell girder, combining with the mechanical characteristics of the corrugated steel web plate. The following are main contents in this thesis:(1) Methods of rigid transverse beam and rigid-connected beam were adopted to calculate transverse distribution coefficients in the mid-span section of composite box-girder with corrugated steel webs. Compared to the calculation results of finite element method, it was indicated that rigid transverse beam method has large calculation error. Comparing the lever method with the finite element method showed that the lever method is more appropriate to calculate the load transverse distribution in the section of support point of composite box-girder with corrugated steel webs.(2) The variation rule of transverse distribution coefficient along the span was studied with finite element method. Calculations manifested that for simple-supported box girder bridge with corrugated steel webs, the lever method is appropriate for section of support point while sections between one thirty second and thirty one thirty second of one span have the approximate tansverse distribution coefficients as that of mid-span section and the coefficients of rest sections present rule of linear transition.(3) Based on the energy variational method and considering the restrained torsion effect of box girder with corrugated steel webs, the expression of constructing influence line of transverse distribution of loads was deduced.3-D finite element model was established to verify the accuracy of the theoretical formulas. The result made it clear that theoretical formulas met the requirements of precision.(4) Both theoretical formula and finite element method were used to research the the factors’ influence on transverse distribution coefficients, which includes shape parameter of corrugated steel web plate, diaphragm density, thickness of corrugated steel web plate and web inclination. Shape parameter of corrugated steel web plate has little impact on transverse distribution coefficients while diaphragm density makes tansverse distribution coefficients well-distributed. Increasing thickness of corrugated steel web plate can improve torsional rigidity obviously. The change of the web plate inclination mainly affects the width of the top and bottom deck of box girder while web inclination can improve torsional behavior of cross section and impact the transverse distribution coefficients.