Steel Truss-concrete T Rigid Frame Composite Bridge Structure Temperature Effect Analysis

The continuous composite steel-concrete bridge is a new type of composite structure ofconcrete box girder bridge panel and steel truss joint force, Because of its high rigidity, lowstructure weight, good integrity, low noise and driving comfort and a series of advantages,has been widely used in the highway and high speed railway in various countries. But theimpact of sunshine or climate change, steel truss and concrete will produce different degreesof temperature stress and deformation, so it is easy to lead to concrete cracking problems.From the existing research, bridge experts and scholars have done a lot research for thetemperature effect of concrete box girder bridge, accumulated a lot of valuable experience,however, for steel truss-T rigid frame composite bridge effect of temperature and crackproblem has not received enough attention. This paper combined with the new high-speedrailway of a Yellow River Bridge main span single T rigid frame and stiffened steel trusscomposite structure on Da-xi Passenger Dedicated Line engineering, further research on steeltruss-concrete T rigid frame composite bridge temperature field distribution, improving thetheoretical calculation of temperature effect and the test research of real bridge, analysis thecracking mechanism of the steel truss-T rigid frame composite bridge and gives the crackcontrol measures. Based on the above analysis, this paper basis of the previous studies usingthe finite element software to carry on analysis and calculation the composite bridge, somework and achievements in the research as follow:1. Through the analysis of the steel truss structure of sunshine temperature fieldmonitoring and meteorological data, we get the temperature distribution of sunshine andextreme temperature load distribution of the steel truss. According to the temperaturedistribution, analysis of the impact of the steel trusses in the sunshine, extreme temperatureloads, combination of the extreme temperatures and dead and live loads of three load cases.2. Establishment of a Yellow River Bridge main span single T rigid frame and stiffenedsteel truss composite structure finite element model, Analysis and calculation of the bridgesupport vertical reaction force, truss stress and concrete stress and displacement variation ofthe steel truss respectively in the three conditions. We obtained in linear temperature loads,supports vertical reaction force and trusses stress and concrete stress are all linear change. Under the extreme temperature loads, opposing V-shaped steel truss diagonals are always sideby side and pull pressure, heating loads leads the main beam up-warp, cooling load leads themain beam down-warp. Under combination of the extreme temperatures and dead and liveloads, we obtained the most unfavorable situation of bridge as well as the truss stress andgirder stress and deflection change.3. Studied the junction of the connection type of steel truss-concrete composite bridge.Get the mechanism of the influence of temperature changes on truss and concrete joints stress.Establish binding sites dimensional solid finite element model, analyzed the extremetemperature load and combined effects of two kinds of the most unfavorable conditions, gotthe maximum stress position of binding site of the concrete stress situation and crackcondition.4. In this paper, according to the calculation results with related literature, analysis of thecauses and characteristics of temperature crack of Steel Truss-concrete T rigid framecomposite bridge, then puts forward temperature cracks control measures of SteelTruss-concrete T rigid frame composite bridge and guide the design and construction of thiskind of bridge.