Recently, the finite element method is often used for structural analysis. This method, however, requires preparation of cumbersome input data and the long running time of a computer for calculation. Accordingly, we intended to develop programs for specific subjects by taking into account the accuracy needed, easy application of the program, etc. Usually, structures are composed of not only beam-elements, but also connection parts of these beam-elements. We developed our program by the finite element method combined with the beam theory for the in-plane stress analysis. In this program, the amount of input data is reduced by treating plate-elements of the same type by common data. These elements can be easily applied for elements rotationed, turned inside out and homologous. The results of calculation are poor in accuracy for some cases, and we studied the nature of the error and established a method to minimize it.
