Study On Temperature Effect Of Thin-wall Hollow High Pier In High Altitude Canyon Area

With the implementation of China's western development strategy,the focus of traffic construction to the western region,the northwest region is high,undulating terrain,more canyons,these unique terrain,geomorphology decided to build a large number of high pier bridge.In the northwest region,alpine,hypoxic,arid,windy and windy,especially in the Qinghai Plateau,the continental climate is characterized by low temperature,large temperature difference between day and night,less rainfall,long sunshine and strong solar radiation.In this construction,the construction of high-pier bridge will face many problems,in which the sunshine temperature effect on the construction and use of thin-walled hollow high pier bridge has a significant impact,due to sunshine radiation caused by hollow high pier uneven temperature field distribution,resulting in a large Temperature stress and deformation displacement,resulting in high pier cracks,affecting the use of the structure,and even lead to safety incidents.In this paper,based on the research project of "Key Technology of High Pier Bridge Construction in High Altitude Canyon Area",this research project is supported by G310 large highway project Wo Longgou No.4 bridge.Through the on-the-spot observation and analysis,the sunshine temperature effect of the thin-walled hollow piers in the high-altitude canyon area is studied deeply.The main contents are as follows:Based on the measured data of the temperature field of the 6 # pier of the bridge,the distribution law of the temperature field of each wall of the hollow pier under sunshine radiation is analyzed,It is found that the temperature rise of the internal concrete is obviously lagging behind the outer surface.The smaller the distance from the outer surface to the outer wall,the position outside the wall from the outer wall to the inner wall is almost free from the sunshine temperature.On the basis of predecessors,the formula for calculating the temperature field distribution of thin-walled hollow piers suitable for high altitude is obtained.Compared with the measured temperature data,it is proved that the formula has certain accuracy.After analyzing the heat transfer boundary conditions of the hollow pier at the bridge site,the surface model of the sunshine temperature field of the hollow pier is established by ANSYS finite element software.The distribution of the temperature field of each wall of the hollow pier is analyzed.At the same time,Data comparison,verify the correctness of the model.Based on the plane model analysis,the stress distribution of the transverse temperature difference of the sun pier was studied,including the transverse bridge stress and the longitudinal stress.Under the sunshine radiation,both of them showed external compression and internal tension,and the greater the temperature difference,the greater the stress value.The finite element model of Wo Longgou No.4 bridge was established by ANSYS.On this basis,the effect of sunshine temperature on hollow pier was analyzed,including vertical temperature stress and temperature displacement.It was found that vertical temperature stress was closely related to temperature displacement.The temperature displacement caused by sunshine temperature difference is very large and the maximum reaches 29.2mm,which exceeds the allowable value of the specification.It is proposed to use stable temperature field method and precontrol method to reduce the sunshine temperature displacement and ensure the vertical degree of pier body during construction.