Analysis Of Shear Lag Of Single-box Multi-cell With Corrugated Steel Web

Sustainable development,light weight,high strength,long span and assembly are a trend of modem bridges.Cracking and midspan deflection of reinforced concrete and pre-stressed concrete bridges and fatigue damage of steel bridges will bring huge economic losses and endanger people's lives in serious cases.Steel-concrete composite structure provides a new choice for modem bridges.PC composite bridge with corrugated steel webs,as a kind of steel-concrete composite structure bridge,can be well applied to various landforms and has a wider application prospect.In recent years,PC composite bridge with eorrugated steel webs has entered a period of rapid construction in China.Domestic scholars have also carried out one of these bridges.The main content of this paper is to study the shear lag effect of PC composite girder bridge with corrugated steel webs with single box and multi-compartment and variable cross-section,which is a relatively new subject.Referring to the relevant information,the research on the shear lag effect of single-box single-chamber corrugated steel webs simply supported beam has been relatively mature,and the research on the shear lag effect of single-box multi-ehamber corrugated steel webs continuous beam with variable cross-section is still in its infancy.Based on the engineering background of Xinyuxi River Bridge in Anhui,the shear lag effect of corrugated steel webs continuous beams with single box and multi-chambers and variable cross-section is studied by numerical simulation.The main research results and conclusions are as follows:(1)Under the maximum cantilever condition of corrugated steel webs,the positive shear lag effect caused by concentrated load is more serious than that caused by uniform load when concentrated load or uniform load acts on the intersection of web and roof of corrugated steel webs.Under uniform load,the shear lag effect of box girder roof along the longitudinal L/4 of the cantilever beam will change sign.This phenomenon does not occur under concentrated loads.It can be judged preliminarily that the form of external load is an important factor causing negative shear lag effect.(2)When corrugated steel webs are in the maximum cantilever state,no matter what kind of eccentric load,the box girder with corrugated steel webs will have obvious shear lag effect.The maximum shear lag coefficient of corrugated steel webs is often located at the loading point of load,and there is a positive and negative change in its shear lag effect,which can not be ignored in design and construction.(3)The change of roof width has the greatest influence on the shear lag effect of continuous beams with corrugated steel webs in the completed bridge state.In this paper,the influence of geometric parameters of corrugated steel webs with four spans,single box and three chambers on shear lag effect is analyzed by finite element model.When the sensitive geometric parameters such as corrugated steel webs thickness,corrugated steel webs wave height,width-height ratio and roof width change,the change of roof width brings the most serious change to the shear lag effect of corrugated steel webs continuous box girders.The influence of parameters on shear lag effect of continuous box girder with corrugated steel webs can be neglected.(4)Regression analysis is made on the most sensitive parameters of corrugated steel webs,and the formula for calculating the effective width of the upper and lower flange plates in the middle of the maximum span is obtained.