Study On Temperature Field Distribution And Its Influence On Alignment Control Of Extradosed Bridge

In bridge engineering,the effect of temperature always has been one of the key concerns for designers.The effect of temperature in longitudinal as well as transverse produces stresses which can cause cracking and pose threat to the safety of the structure.In bridges,the longitudinal temperature at the deck top is almost uniform while the temperature gradient produced in transverse direction may be large.There have been studies on effect of the temperature gradient produced due to various reasons but most of the researches have been limited to the simplified two-dimensional approach which holds sufficient accuracy for traditional bridge under a range of conditions but for modern bridges which continue to evolve into complex structure,and are often subjected to erratic temperature variations is deemed insufficient.The prediction of temperature effect in three-dimensional temperature field is complex and there is no concrete theoretical/empirical method that is fit for all situations.The metrological parameters that dictate the temperature field greatly vary from site to site as the bridges are constructed in varied topoclimate.Furthermore,in many cases the metrological stations lack the data required to consider temperature field that further makes it difficult to take into account the impact of temperature from early stage of construction.Thus,there is a need to investigate and establish a reliable theoretical model to calculate the metrological parameters for the site topoclimate.The main work is as follows:(1)According to the theory of solar astronomical model,the radiation intensity on different parts of bridge was calculated with the aid of program developed in Python.The influence of various variables(longitude,latitude and azimuth)on amount of solar radiation on bridge is also calculated and analyzed.(2)The temperature distribution of the representative bridge span was simulated in the finite element software ABAQUS by using the radiation value as the boundary condition with convection and radiation.(3)The value of uniform temperature and temperature gradient was obtained from Abaqus analysis and was applied in Midas civil model of the bridge to see the impact of the temperature on pylon and box girder.(4)From the analysis of the model in Midas civil the deflection caused by temperature was obtained,and the basis to obtain amount of correction in formwork elevation during pouring concrete at any time of the day was found.