Arch Boundary Temperature And The Transient Stress Calculation And Analysis

As an important dam type, arch dam occupys very prominent position in water conservancy and hydropower construction, have been widely used at home and abroad with reasonable structure, beautiful shape, high security and economic advantages.Because of its own high order hyperstatic structure speciality, the influences of temperature changing on the body to stress is significantly. Measured data shows that the temperature load impact to the dam overall stress is the same order of magnitude with that of design, as the self-determination of the dam and the hydraulic load, so it is particularly important to accurately calculate the temperature load on the arch dam design. Boundary temperture is the basic to caculate the arch dam temperature loads accurately, especially the temperature of upstream under-water part that is the reservoir water temperature. Traditional methods of reservoir water temperature are all empirical formula such as DongKan method, Zhu Bofarig method and Statistics method in accordance with the measured data, which reflect the statistics rule of the water temperature changing, while there is no similar built reservoir project, the difference between prediction and actual is large, with much limitations in application. In this paper, according to the mixed water temperature mechanism of the reservoir, given that vertical temperature distribution of one-dimensional mathematical model, derived from the thermal balance principle and gained its Galerkin finite element method solutions.Arch dam is a spatial shell structure with variable thickness, curvature and complex boundary conditions, and the stress condition in operation period is more complicated. therefore, calculating arch dam transient stress of run-time and analyzing the most adverse load combination play a decisive role in arch dam design. At present, normal arch dam stress analysis methods are mostly multi-arch beam method and finite element method. Finite element method theory is much relatively precise, improved and advanced than multi-arch beam method. In this paper, using finite element analysis software ANSYS10.0 as a platform, adopting Boolean operation method to create a solid model in accordance with the dam geometric equation, formed grid of finite element model with SOLID98 unit (a kind of 10-node quadratic tetrahedral space coupling unit, each node with four freedom degrees, X,Y,Z direction of displacement and temperature, adapt to complex boundary surface).While caculating transient stress of arch dam, imposing the transient nonlinear temperature load and other constraints with direct coupling thermal-structure method in ANSYS software, solved the arch dam transient temperature field and stress field in one time, and checked that with the norm working condition of temperature rising and dropping.This paper generalizes the traditional methods of prediction to upstream underw-ater temperature and carries out the finite element solution of its mathematical model, recalled the principle of finite element analyzing arch dam stress. Compared with different water temperature prediction methods using ANSYS software, finally calculated the arch dam temperature field, stress field and displacement field in transient boundary conditions, analyzed contrastively the calculational results.