This dissertation applies 3 - d finite element theory to development of the shape functions and stiffness matrixes of the triangular prism isoparameter elements ( 6 to 15 nodes ) . a calculating method for gaussian integral in triangular prism is presented . the stress field in welded steel structures can be computed by the triangular prism isoparameter elements ( 6 to 15 nodes ) and hexahedron isoparameter elements ( 8 to 21 nodes ) 本文应用三维有限元理论，构造了一类五面体6 15节点单元的形函数，提出了在五面体单元内的gauss积分处理方法，建立了相应的单元刚度矩阵，将其与六面体8 21节点单元结合，可用于计算焊接钢结构的应力场。
