The Research On The Thermal Response Of The Super-length Concrete Structure

Lots of large-span, large-area concrete building floors are widely used.As the requirement of integral performance in architecture and structure, seamless system is adopted in many structure styles. To the super-length concrete seamless structure, the important influences of temperature action on structure are taken into account in structure design. The difficulties of calculation are to establish the temperature field of structure under the action of ambient temperature and to calculate the thermal stress and thermal deformation. Exceptly, monitoring on the thermal response is not abundant. So, it is important to study and monitor the integral thermal response of super-length concrete structure. This thesis draws lessons from the research approaches of some scholars on the basis of existing research results and does some reseaches on establishing temperature field, calculating thermal response and analyzing the effect of prestress action by using study methods of theoretical analysis and site test research as the example of the engineering of Lanzhou mobile communication hinges.Firstly, in the sight of basic principle on conductions of heat, Fourier heat conduction differential equation of temperature field is founded. Based on analysis on the influence on variation of environmental temperature and solar radiation, a computation model of inner temperature field in concrete members is built up according to the situation of the thesis and site monitoring. The analytical solution of inner temperature field is done. Considering the heat convection and conduction analysis on the distribution law of inner temperature field in concrete members by using finite element programme ANSYS. From the temperature isopleth of member section, the distribution law of inner temperature field is analyzed.Secondly, the design temperature difference value of super-length building under the action of ambient temperature is ascertained on the basis of the code requirement. The temperature response of structure is calculated by using the three dimension finite element progrmme and simplified method. From the analysis on the deformation and inner force, some conclusions are drawn that the deformation and inner force should be checking computated as the value of work condition 1 and work condition 4 in the design of super-length buildings in order to contral the thermal crack.Thirdly, unbonded prestressing technology is used to solve the temperature problem in this thesis. By comparing the result of analysis on deformation and inner force of structure by using prestressing and non-prestressing under the action of temperature, a conclusion is drawn that this technology is effective. Furthermore, the data of monitoring in site demonstrates the result of theoretical analysis.Finally, some conclusions and suggestions that are important to design are obtained, and which provides a good basis for the further research of structure behavior with the thermal action.