Research Of Temperature Effect Of Short Pier Rigid-frame Prestressed Concrete Continuous Box Gride Bridge

Continuous rigid frame bridge has some remarkable features such as great stiffness, goodstability, large clearance under the bridge, low maintenance cost, which make it extremelysuperior in the choice of bridge across the river valley. Considering the mechanicalcharacteristics of long span continuous rigid frame bridge, form of bridge piers is with highones rather than short ones. This is because the high pier flexibility is big, it can well adapt tothe concrete shrinkage, creep, temperature fluctuation, caused by the tensioning prestressedpier top displacement. However, restricted by bridge scale and hydrogeological conditions,the short pier continuous rigid frame bridge has a big advantage. Short pier continuous rigidframe bridge can adapt to the pier top displacement caused by the load needs furtherdiscussion and research. In this paper, the author will take the Dong guan Channel Bridge forthe engineering background and choose the most representative weather and climate in oneyear in the atmospheric environment and open real bridge to do some observations on thetemperature field of box girder as well as analysis of the temperature field and effect of boxgirder with the aid of finite element software ANSYS and Doctor Bradge. The main contentsand results are as follows:1. Calculation of integrated Short pier continuous rigid frame box girder temperaturetable has been achieved through some relevant meteorological data, related parameters of thetest from meteorological offices and measured data given by some references of temperaturecalculation. The measured temperature data of each panel shows that under the effect of sunradiation, the temperature changes with time by sine law and lags behind temperaturechanges.2. By comparing the field measured data of Dong guan Channel Bridge with thecalculation result figured out with the aid of finite element software ANSYS simulationmodel, we have been informed of a temperature gradient mode of short pier rigid-frameprestressed concrete continuous box girder bridge that is suitable for the regionalcharacteristics. Of all the factors influencing the temperature gradient, solar radiation intensityis the greatest one, then coming the daily maximum temperature difference and terrier axillaryshape, and the rest of the factors such as box girder geometry, as well as bridge azimuth havelittle impact. Of those factors, the solar radiation intensity and the daily maximumtemperature difference have some impact on maximum vertical temperature difference andpositive temperature gradient curve of concrete box girders while the shape of axillary terrier would have affected the temperature gradient curve of concrete box girder. When thetemperature load in this article have been compared with the provisions of temperature load athome and abroad, it will be verified that the result of calculation is reliable, feasible and thuswill provide reasonable suggestions for the modification of specifications.3. Through analyzing the finite element software ANSYS the simulation model, it isconcluded that the temperature effect in construction stage and operation stage of short pierrigid-frame prestressed concrete continuous box girder bridge can not be ignored in the design.Researches have shown that under the unfavourable temperature gradient, the roof surfaceof box girder, outer surface of the web and lower surface of base plate are under pressurewhile surfaces opposite to each plate respectively the tension when they are all under thecondition of cantilever. The box girder displacement would have increased when the length ofcantilever enlarges. Temperature time stress ratio of box girder panel after folded is muchmore complex than temperature self-stress. After shut box girder become warped on thedisplacement with the maximum value near the mid-span of each span.4. With the analysis and calculation about double limb thin-walled short pier of Dongguan Channel Bridge, we have obtained that under the extreme hot weather conditions,maximum tensile stress appears at the top of the pier, up to8.7MPa, the maximumcompressive stress in the pier, ascend up to6.77MPa. While in the extreme cold weatherconditions, however, the maximum compressive stress appears at the top of the pier, up to6.52MPa, the maximum tensile stress in the pier, ascend up to5.09MPa. Therefore, in viewof the temperature stress produced by double limb thin-wall dwarf piers, relevant measures toimprove the stress state of short piers should be taken such as pushing,weight adding andbridge closure order adjusting, etc.