Analysis Of Temperature Stress Caused By Hydration Heat Of Skew Frame Bridge

The current transportation industry in China is developing at an extremely fast speed,and the number of railroad crossings between railways and highways has increased dramatically.The main form of changing from a level crossing to an intersection is the frame bridge.At this stage,with the increase of the requirements for the size and bearing capacity of the frame bridge,it has already entered the scope of large-volume concrete,and the large-volume concrete will obviously heat up due to the heat of cement hydration during the construction period,resulting in a large temperature difference.It causes temperature stress and is prone to cracks during concrete curing period.Therefore,it is very important to study the variation law of early concrete temperature field and stress field.At the same time,due to the limitations of the original building,the existing route line type or the economic aspect,the frame bridge is often required to adopt the form of skew,so the skewed frame bridge is increasing.The temperature field and stress field distribution are quite different from those of the general frame bridge.Based on the oblique frame bridge project of the South Ring Road of a city,this paper studies the temperature field and stress field caused by the hydration heat of the skew frame bridge.Based on the selection of construction scheme,on-site temperature and stress monitoring,and considering the climatic conditions during construction,the ANSYS finite element analysis software is used to establish a finite element model for the frame bridge at a certain node,and the skew frame bridge is calculated.The temperature field and stress field after the mold is introduced,and analyzed,and the rules and characteristics are summarized.The details are as follows:(1)Review domestic and foreign literatures,summarize the research status of large-volume concrete hydration heat problems,and initially grasp relevant research methods.Combine with the city's Huancheng South Road project to determine the research method and writing outline of this paper.(2)The thermal characteristics of mass concrete materials are mainly described,and the calculation method is selected based on the heat conduction theory and the large-scale concrete heat release model.(3)According to the structure of a railway frame bridge under a certain city,the finite element model of the skew frame bridge is established,the temperature field of the field frame bridge and the stress field caused by the frame are simulated,and the temperature field and stress field are analyzed and summarized during the whole process.The distribution characteristics and the law of change,and use this as a theoretical basis to develop an on-sitemonitoring program.(4)By changing the parameters,the effects of ambient temperature,solar sunlight,mold temperature,skew angle and sidewall thickness on the temperature field and stress field of the large-frame frame bridge after the large-volume frame bridge is introduced into the model are discussed.The finite element results are analyzed.,summarizing the temperature field and stress field characteristics.