Study On Shear Lag Effect And Application In Construction Process Of Cable-stayed Bridge With Wide Double-ribbed Girder

The cross-section of the double main ribbed cable-stayed bridge consists of two side main ribbed and wide bridge panels.For the thin and wide beam cross section,shear lag effect is obvious,if in the process of design and construction control ignore the effect of shear lag may cause accidents.By taking Xinan Bridge as project background,through a series of theoretical analysis,finite element model calculations and bridge construction stress monitoring results,this thesis made a deep analysis on the changing situation of such shear lag effect in girder section of double-girder cable-stayed bridge in construction.Following aspects have been completed in this paper.(1)With energy variation method,it further explored shear lag effect happening in double girder section.Supposing longitudinal displacement of flange plate is a quartic parabola,it deduced one ideal shear-lag-effect calculating formula for main-girder flange plate accordingly.(2)By taking Xinan Bridge as study object,it further established the variation trend of shear lag effects of girder part under the forces of girder-body dead weight,tension load,hanging-basket dead weight,pre-stressing load and concrete wet weight with the application of finite element model analysis separately.(3)Considering of sustainable impact in construction,it further analyzed stress variations under the four continuous constructing conditions in subsequent block sections for each section of poured girder.(4)According to the Xinan of the bridge construction process of monitoring cross section of the test point stress of each monitoring data,combined with finite element analysis and calculation results,analysis of main girder cantilever construction process of shear lag characteristics and change(5)Analyze the influence of transverse slope of deck and thickness of section roof shear lag of cross section.