Abstract: In this paper the use of the mixed finite element method for stress analysis of reinforced conical branch pipe junctions subjected to internal water pressure is presented, branch pipe junction being considered as an intersection body of two thin conical shells. For the purpose of computing a large number of branch pipe junctions with different geometrical varieties, an automatical meshing routine has been put up in the mixed FEM program with 3 geometrical parameters of the junctions to be varied, i.e., the angle included between axes of the main pipe and the branch pipe,the thickness of the wall of the shell and that of the reinforcing pad and the ratio of diameters of the branch pipe to that of the main pipe. The computer program has been provided functions to distinguish 8 kinds of different meshes and 12 sorts of elements, and to lay automatically coordinates of nodes as well as different boundary conditions of elements. In this way, stress analyses of 101 junctions have been carried out and results of computations are excellent.

Key words: shallow shell of variable thickness, nonlinear stability, modified method of multiple scales