Study On Diurnal And Seasonal Temperature Effects Of Thin-walled Hollow High-pier Concrete Structures

Concrete is one of the most common and important materials in engineering.Since the1950 s,people began to realize the critical influence of temperature stress on concrete structure,and more and more engineering accidents also prove its importance.As can be seen from the development history of temperature stress,the initial understanding of temperature field is from simple to complex,from one-dimensional to multi-dimensional,from linear to nonlinear,from steady state to transient,from single influence factor to multiple influence factors,from single subject to multi-subject combination.In this paper,the method of combining actual data collection and finite element numerical analysis is adopted for research.The main work is as follows:1.The mechanism of temperature stress' generation,the basic theory of heat conduction and the finite element method of thermal stress are elaborated systematically and detailedly.The calculation method of boundary conditions of concrete facilities and the calculation method of various parameters involved are also elaborated in detail.2.The annual temperature change process and wind speed change process of the location of Chongqing Sunxi river bridge were obtained through a large number of data collection,and the three most representative temperature models were selected as the temperature load applied on the concrete facilities for analysis.3.Finite element software ANSYS was used to analyze the variation rules of temperature field and stress field of piers of Sunxi river bridge under various temperature modes,and the causes were analyzed.Through the analysis shows that high temperature and high radiation conditions using phase and construction phase of the concrete temperature fluctuations and stress is very severe,low temperature under the condition of the construction phase of the temperature stress under without heat preservation measures will exceed the allowable tensile stress value,the stress value of concrete under cold conditions will continue to increase,if early ripping at construction stage,will produce a large stress mutation.4.The influence of various parameters on the maximum temperature difference wasquantitatively analyzed,and the functional relationship between the parameters and the maximum wall temperature difference was fitted,and then the sensitivity of the maximum wall temperature difference to various parameters was analyzed.The results show that the maximum wall temperature difference is very sensitive to the ambient temperature and the wall azimuth,but not to the convection heat transfer coefficient(or wind speed)and the thermal conductivity of concrete.Except the rest of the parameters of the sensitivity of azimuth are monotonic function,azimuth is around 240 ° surface temperature difference of azimuth Angle is the most sensitive.The functional relationship between concrete and parameters during construction stage and use stage is different or even completely opposite.