Study On Adjustment Method And Influence Of Environmental Temperature On Installation Alignment Of Steel Tube Arch Bridge

The concrete-filled steel tube(CFST)arch bridge is a typical self-erecting system bridge.After the steel tube arch is closed,the concrete is poured into the steel tube one by one to form the CFST composite structure.Usually long-span steel arch installation time is longer,construction often need to cross the season.Affected by environmental factors such as sunshine and atmospheric temperature,it is difficult to control arch rib alignment.In order to research the adjustment method and influence of environmental temperature on installation alignment of steel tube arch bridge.Based on Qianwei Minjiang Bridge in Sichuan Province,the following research works were carried out:(1)Based on the theory of solar physics and heat transfer,the boundary conditions of hollow steel tube and CFST members under the action of sunlight were studied.Using APDL language of ANSYS finite element software,the calculation program of temperature field distribution in the section of hollow steel tube and CFST under the action of sunlight was worked out.Field tests were carried out on the insolation temperature field of a north-south hollow steel tube member and an east-west CFST member.By comparing the field measured data with the calculated results of the program,the correctness of the developed program was verified,and the distribution law of the temperature field of the hollow steel tube and CFST members under the action of sunlight was obtained.(2)Based on the calculation program,the sensitivity analysis of the parameters of sunshine temperature field on the section of steel tube arch chord was carried out,including the diameter of steel tube arch chord,wall thickness of steel tube,surface coating color of steel tube and inclination Angle of steel tube.The sunshine temperature field of each chord section of steel tube arch under different atmospheric temperature is calculated,and the calculation formula of the sunshine temperature change with time at the characteristic points(top point,bottom point,right point and left point)of each chord section is fitted.Since the insolation temperature field of the steel tube arch chord section is a nonlinear temperature field,the error of directly calculating the gradient temperature through the temperature of the characteristic points of each chord section is large.Therefore,the calculation formula of sunshine temperature equivalent to gradient temperature along section height direction and section width direction of steel pipe arch chord section is deduced and applied to the construction monitoring of a long-span steel arch.(3)Through the analysis of the axis alignment of steel tube arch under sunlight,the influence of sunlight temperature on the axis alignment of steel pipe arch is identified.Combining with the measured results and buckle cable force tension caused by the axis offset,calculate the measured results and the sunshine temperature,deduct the difference between the cable force caused by the axis offset.According to the size of the deviation to axis deviation adjustment measures,solve the problem of the influence of sunshine temperature on the axis alignment of steel tube arch.