Test Research On Temperature Field Of Railway Hollow Bridge Pier

Many hollow piers are used in railway bridges as many railway lines have been built in our country. Under natural environment, these big and high bridge piers bear natural air temperature and solar radiation for long time. Affected by natural air temperature and solar radiation changes and because of its bad heat conduction difference of concrete, the temperature of the piers fast rises or falls down, but their inner temperature maintains, so there will be a large temperature contrast in the concrete structure, and then different parts of concrete structure will be in different temperature state. So the temperature deformation creates large temperature stress when the structure is restrained by the strength in and out. Sometimes, this temperature stress will be larger than load stress on bridges, so sometimes it can directly affect the safety of bridge. But railway bridge rules do not definitely define the temperature load for hollow bridge pier, so it has practical engineering values to do some research in the temperature of railway hollow bridge pier.With Niu Jiao-ping super bridge 3 pier and Xin Yang-jia-wan super bridge 7 pier as engineering background, and on the basis of model test and field actual measurement, this paper studies the heat of hydration temperature field of railway super hollow pier, common solar temperature field of railway hollow pier as well as the effects of air hole on the temperature contrasts in and outside of the hollow pies.The research methods of temperature field of railway hollow pier chiefly used in this paper is the model test in lab and field actual measurement. First it simulates the model test in lab, and then measures the hollow pier temperature field. And at last after contrasting and analyzing the test results, the actual measurement results and the calculation results gets the following conclusions:①The result of the heat of hydration temperature field calculated by ANSYS is reliable and it can be used as reference data before concrete pouring of bridge piers and it can provide information for temperature control method as well as site.②The time of strike form board after concrete pouring should be selected appropriately, and then some corresponding method to reduce the jump of temperature contrast inner and out side should be adopted to reduce the possibility of the crack out of the bridge piers.③For super wall thickness hollow pier, in order to reduce concrete heat of hydration hazard it is necessary to install a certain number of cooling water pipe in the piers to conduct circulated cold water cooling.④The depth influenced by the effect of sunlight on bridge pier temperature field is usually less-than 0.9m of one day. In another word, the temperature field of pier inside will not be influenced by the effect of sunlight with a distance of 0.9m or longer.⑤The temperature contrast in bridge pier generated by the effect of sunlight is an exponent curve generated by the effect of sunlight, which can be expressed as this experience equation:⑥The effect of sunlight itself on the inner and outside temperature contrast of the hollow piers is limited, so usually it cannot yield controlling effects on pier designs.⑦The methods of air hole location in《Bridge Rules》have obvious effects on reducing the inner and outside air temperature contrast of the hollow pier, which is caused by environmental temperature changes and it is for the piers.