The Applicability Research Into The Finite Element Equivalent Stress Method For Stress Analysis Of High Arch Dam

The finite element method has a lot of advantages, but the stress results by this method are always involved with great stress convergence. Fortunately in some degree this kind of stress convergence can be eliminated or reduced to a lower level processed with the finite element equivalent stress method. At present it is doubtable to analyze high arch dam stress with the FEM equivalent stress method. Now the FEM equivalent stress method is being used for arch dam analysis at its initial stage, and its feasibility should be studied about more deeply, especially for high arch dams. So it's necessary to study the validity of the FEM equivalent stress method further for the analysis of high arch dam stress. Firstly this paper introduces the FEM equivalent stress method and the nonlinear cracking FEM, and intends to study the applicability of the FEM equivalent stress method as well as its tensile stress criterion contained in the design specification by comparison with the results gained by both of the above methods. The arch dam stress is analyzed with the ANSYS FEM software. Meanwhile it is easy to calculate the equivalent stress of arch dam by running an APDL program on the basis of the ANSYS result data; and it is feasible to analyze nonlinear cracking stress of arch dam using the concrete65 element and concrete cracking principle. Through comparison with two kinds of stress results and crack development the validity of the FEM equivalent stress method and the 1.5MPa of the equivalent tensile stress limit will be researched for the stress analysis of high arch dam.After comparing two sets of results referred above, it is clear that the FEM equivalent stress method can cut down the stress result calculated straight by FEM and eliminate the stress convergence. The stress values gained by both methods are basically close as well as the stress distribution about the dam height. So the equivalent FEM can be used to analyze the stress of high arch dam. On the other hand, from the nonlinear cracking analysis results, cracks only happen at some local positions, and they are all in a steady-going state. It's clear that these cracks have not any important impact on the arch dam's working order. Meanwhile the greatest equivalent principle tensile stress is less than 1.5MPa.So the 1.5MPa of equivalent tensile stress limits by the current design specification is also feasible.