Research On Effective Distribution Width Of Long Span Box-girder With Corrugated Steel Webs And Various Cross-section

As a new type composite structure,shear lag effect of composite box-girder with corrugated steel webs is more severe.Theoretical analysis method and finite element method are used to study effective flange width of long span composite continuous box-girder with corrugated webs and variable cross-section in this paper.The main work involved in this dissertation are as follows.Firstly,the research status on shear-lag effect of box-girder in China and abroad is introduced.Then functions of shear-lag warping displacement of composite box-girder with corugated steel webs is defined.Based on the principle of minimum potential energy in Energy Variation Method,computational formulas of longitudinal normal stress and shear-lag coefficient in flanges of three-span composite continuous box-girder with corrugated steel webs are obtained under concentrated load and uniform load respectively.Research shows that,numerical results using computational formulas are in good agreement with those using finite element method.Based on built long span composite continuous box-girder bridge with corrugated steel webs and variable cross-section,finite element analysis on shear lag effect is systematically conducted.Based on finite element software Ansys,influence factors of shear lag effect such as web thickness,width height ratio,width span ratio are analyzed.Finally,the main geometric parameter,influence extent,and variation trend working on shear lag effect are confirmed.Loading type is modified according to engineering prctice.Under actual surface load,effective width ratio with the only factor is obtained based on parameter sensitivity analysis.Then based on polynominal regression method,empirical fomulas and calculation form are raised with the only factor of width span ratio.Based on modern code,modification coefficients for effective flange width ratio are finally put forward.Take built long span composite continuous box-girder bridge with corrugated steel webs and variable cross-section for example,reliability of empirical fomulas and modification coefficients are finally verified.