Study On Solar Radiation Temperature Field And Effect Of Hollow Concrete Pier

Due to the effect of long-term environmental factors such as air temperaturevariations and solar radiation, concrete bridge structures induce time-varying non-lineartemperature distribution, resulting in thermal stress and temperature deformation. Insome cases, the stress generated by thermal load is larger than others, leading to theemergence and development of the structural cracks in concrete bridge, which canseriously affect the normal use of the structure, and even endanger the safety of thestructure. Therefore, studying on the temperature load and thermal stress is veryimportant for controlling the cracks of the bridge structure.This paper, supported by "Technology Research on High Pier Structure Design ofMountain High-speed Railway Bridges", with engineering background of XinfuyuanReservoir Bridge, combined with temperature field observation experiments of solarradiation on pier models, deeply analyzes the temperature effect of solar radiation onconcrete hollow piers. The main research contents and conclusions are summarized asfollows:The boundary condition model in concrete pier subjected to solar radiation aresystematically defined by using of the FEM package（ANSYS）, and a more refinedmodel are established for analyzing solar radiation temperature field. The observedtemperature data are compared with the finite element results of temperature field in thepier segment model. It is proved that the ANSYS computational model and theboundary condition model of heat transfer are accurate and applicable. Throughanalyzing the solar radiation temperature field in the background bridge piers, thevariation of temperature difference during one day between the inside and outsidesurface of each slab is obtained. The influence caused by the changes of bridge axisazimuth on solar radiation temperature field in piers is studied. It shows that thetemperature distribution in pier wall is closely related to bridge position and orientationof pier wall surface.The variation and distribution laws of solar radiation transverse thermal stresses inpiers and the effects of thermal stresses in respect of geometry size of pier section andtapered haunch are studied. The two-way temperature difference combination should beconsidered when calculating the solar radiation transverse thermal stress and the effectof two-way temperature difference combination on transverse thermal stresses in the afternoon is more significant than that in the morning. It seems that the change of eachslab thickness has great influence on transverse thermal stresses. If the tapered haunchis out of consideration when calculating the transverse thermal stress, the results will beunsafe and divorced from reality.The variation and distribution laws of solar radiation vertical thermal stresses inpiers are analyzed. The thermal stress and temperature deformation caused bytemperature gradient of the southwest side(T_y=17e^-5.7y)and the northwest side(T_y=14e^-7.0y) in the pier are calculated. When the pier is under temperature gradientof the southwest （or northwest） side, the vertical stress distribution on eachcross-section of the pier is similar and the vertical stresses changes severely onsouthwest （or northwest） pier wall. However, the vertical stress on the rest pier wallsis more evenly distributed. When taking the top of pier is unconstrained intoconsideration, a greater bending will be induced on piers in the transverse （orlongitudinal） direction.