The Calculation And Research With 3D Finite Element Method On Arch Dam Equivalent Stress

Arch dam is three dimensional elasticity shell structure. The scale shape, boundary condition and stress state of arch dam is very complex. Therefore it is very difficult to compute the stress state of arch dam with strict theory. Before 1970s, crown cantilever method is usually used in China. After 1970s, multiple arches and cantilevers method and finite element method is popular. And finite element method is more and more used in stress analysis in China, but the result computed by finite element method always greater on the place between dam body and bedrock due to stress concentration ,this is unconformity practical considerations. This paper based on the concept of equivalent stress, synthesis cross section internal force with result on the place between dam body and bedrock computed by finite element method, then solved the corresponding linear stress, expected to eliminate the grid effect and stress concentration.This paper Combined with the practical project, calculation and analyzes the three dimensional finite element equivalent stress. The capital work of this paper are as follows: Based on the data, the paper summarizes development situation of arch dam, the actuality of stress analysis methods and finite element analysis method; The paper introduces the basic theory, deduces the basic formulae, and states the units and suitable condition of finite element method; Based on ANSYS, the paper studies the finite element equivalent stress of arch dam.. Three dimensional finite element models are established. According to the different condition of project, the results which is advantaged to the project is gained;The result Indicate: under basic load combination, the max is 1.31MPa,lessthan 1.50 MPa; under particular load combination, the max equivalent tensile stress is 1.85MPa,lessthan 2.00MPa;this result meet the design specification of concrete arch dam about the prescription of equivalent stress, under basic load combination and particular load combination, the max equivalent compressing stress all lessthan 5.0 MPa, meet the control standard of design stress.Compared with the result computed by finite element method and multiple arches and cantilevers method (four direction adjust), the regularities distribution of stress is substantial agreement: under basic load combination and particular load combination, the max compressing stress appeared at arch crown of upstream face, dwindle away to side banks ,the tensile stress is bigger at arch abutment; the max compressing stress appeared at arch abutment of downstream face, dwindle away to arch crown, the tensile stress appeared at arch crown and adjacent areas.