Study On Sunshine Temperature Effect Of Corrugated Steel Web Composite Box Girder Bridge In Northwest Arid Area Based On Field Measurement

The current design code for bridges and culverts mainly considers the unified temperature gradient formula for the temperature design of bridges and culverts in various regions of the country.However,meteorological,geographical and other factors have a significant impact on the bridge temperature,especially for the northwest arid areas with large solar radiation intensity,large sunshine temperature difference,dry climate and little precipitation,the sunshine temperature has a more unfavorable impact on the safety and durability of composite beams.Based on this,in order to study the temperature field and temperature effect of composite box girder bridge with corrugated steel webs in northwest arid area,the following aspects are studied on a composite girder bridge with steel floor,corrugated steel webs and concrete roof in Lanzhou New District:(1)Analyze the existing research methods and conclusions of bridge temperature field and temperature effect;This paper introduces the relevant provisions on the temperature gradient of composite beams in the design codes of bridges and culverts in various countries.Summarize the main unsolved problems in the study of temperature effect of composite beams so far.(2)From the angle of temperature transfer of composite beams,three common methods for solving temperature field are introduced.The second-order differential equation for transient thermal solution of composite beams is emphatically analyzed,and suitable initial conditions and boundary conditions are selected for finite element solution of temperature field.(3)Taking a bridge in Lanzhou New District as the engineering background,the temperature observation test is carried out,and the measured temperature field of the composite beam is obtained by sorting out the data;The most unfavorable temperature field is selected,and the measured temperature data are fitted by least square method to obtain the semi-theoretical and semi-empirical formulas of the most unfavorable vertical and horizontal temperature gradient of composite beams.(4)Establish a refined finite element model of the whole bridge,and set up five load conditions,namely,overall temperature rise,overall temperature drop,temperature gradient based on actual measurement,temperature gradient in China’s highway specification and temperature gradient in British BS-5400 specification,and load the finite element model under various conditions to find out the corresponding temperature effects under various conditions,and make a comparative analysis.(5)The meteorological parameters in Lanzhou in recent ten years,including atmospheric temperature difference,solar radiation intensity and wind speed,were collected by the Meteorological Bureau,and the data were statistically analyzed to obtain the standard values of meteorological parameters in a certain recurrence period;By changing the meteorological parameters in the finite element model and the section size of the composite beam,the influence of various factors on the temperature field of the composite beam is explored.