The Temperature Effect Of The Steel-concrete Composite Cable-stayed Bridge During The Construction Phase In Arctic-alpine Region

It is an important premise to speed up the development of the western region to build a more perfect traffic network in the arctic-alpine region.There is more alpine and rivers in the Western Plateau,so the proportion of bridge and tunnel is very large.Steel-concrete composite structure is the development of two common structural forms of steel structure and concrete structure.It fully exerts the respective advantages of steel and concrete.The steel has high tensile strength,good ductility,and the concrete has high compressive strength and rigidity.The steel-concrete composite girder cable-stayed bridge has a good technical and economic benefit,and it is more competitive between 300 m ~ 600 m span.The construction of steel-concrete composite girder cable-stayed bridge in the western alpine region has a great development prospect.As to the special geographical environment and climatic conditions of the plateau in the western,the construction of bridges is difficult in the condition,and the construction period is long and the temperature effect is significant to the structure during construction.It has practical significance to study the temperature effect of the steel-concrete composite girder cable-stayed bridge due to its large span and more flexibility,which cause big displacement and internal force during construction stage.This article,which is based on the Wa Jiatan Yellow River bridge and the meteorological data of Xi ning station nearly five years,uses ABAQUS to analysis the temperature field of composite girder,cable and tower of the composite cable-stayed bridge.And take a truss model to consider the temperature effect of the composite bridge during its construction stage.Sum the temperature field distribution characteristics under the conditions of sun radiation in four seasons and the influence of the temperature to the displacement of composite beam and tower,the force of the cable and the beams.The effect of maximum double cantilever condition and maximum single cantilever condition is analyzed emphatically.The results show that: temperature difference is big between deck and cable,it is 10.8 ? in summer,7.3 ? in winter.Bridge tower and cable temperature difference is 10.2? in summer,8.3 ? in winter.Temperature gradient of composite beam is the largest,followed by the bridge tower,and the cable temperature gradient is small.Under the action of temperature,the control parameters for construction such as the composite beam elevation,the tower top offset,the force of cable and so on,change significantly during the day.The displacement of girder is up to 87 mm,the tower offset is 32 mm,cable force changes up to 4.1% of the control force,and the steel girder bending moment changes 32.9% of the construction.The first step is to set up the steel girder of the composite cable-stayed bridge,and then install the prefabricated deck,and pour vertical and horizontal wet seam.Before the wet seam concrete reaches its strength,the cable force and the deck weight act on the steel girder.When the wet seam concrete achieves the design strength,the steel girder and the concrete deck form a combination section,and then the load acts on the composite beam.In the process of the wet seam achieving its strength,the change of the nonlinear temperature field of the composite beam is disadvantageous to the wet seam.This paper analyzes the changes of temperature stress in a standard segment(E5 segment)during the solar diurnal variation.The results show: In the process of forming the strength of the wet seam concrete,the sunshine temperature stress will exceed the tensile strength value,and the daily variation of the tensile stress is larger,up to 3.8MPa.The results of temperature effect analysis can provide a reference for the temperature effect of similar bridges.