Analysis For Temperature Stress Of Superstructure Of Cast-In-Place Simple-Box Double-Cell Bridge

With the development of transportation industry in our country, The bridge construction come into a period of unprecedented prosperity. The prestressed concrete box girder bridge is often chosen as the best bridge scheme because this kind of bridges have many advantages such as large stiffness、large torsional、good overall、driving smoothly and so on. But in recent years,when we use the process of prestressed concrete continuous box girder bridge at home and abroad, we found a lot of bridge cracks. This phenomenon has attracted the attention of a great bridge experts and researchers both at home and abroad. These scholars proved that the temperature stress is a major cause of bridge structure cracks. China’s vast territory, latitude span is big. Bridge structure is decided by the external environment temperature field. So different parts of the bridge structure temperature field, the temperature stress field is also different. There is only a vertical temperature gradient in the existing bridge specification "General Code for Design of Highway Bridge and Culverts"(JTG D60-2004). This lead to a temperature gradient has no value in typical faults. So looking for different parts of the bridge structure accurate temperature gradient distribution patterns has become an important problem for us to solve.This article takes prestressed concrete continuous box girder bridge of Harbin songpu as the research object. I have taken observation on the data of the temperature and stress of the tested beam for a long time. Based on the measured temperature data and stress data, I analyzed the different cross section temperature distribution, the same measuring point temperature change rule, the vertical temperature gradient distribution,the distribution cross the bridge to the temperature gradient, the elevated to temperature stress and the transverse to the bridge temperature stress respectively. I summed up the regular pattern of the test beam temperature and thermal stress distribution and fitted out of the test beam of maximum temperature gradient formula. I find the codes and regulations of test beam load and temperature gradient temperature gradient load has great difference. Using the finite element software ABAQUS, I used the sequential coupling method to calculate the temperature and stress distribution of the test beam.I found the test beam under fitting negative temperature gradient load produced by the tensile stress is greater than in the normal temperature gradient loads occur tensile stress by contrast the test beam temperature gradient in the specification under load and fitting temperature gradient load stress distribution.