Abstract: The section of beam designed according to the internal force envelope diagrams can meet demands of security and economy. But the process of drawing the internal force envelope diagrams of the beams using the classical mechanics methods is overelaborate, especially multispan beams such as continuous beams. So, a new method for arbitrary continuous beam analysis and its intelligent software with singularity functions are introduced. The general expressions of the continuous beams deformation and the internal force are developed, using a method combining singularity functions with Laplace transformations, and binding reactions are determined by boundary conditions and deformation conditions of the beams, then an automatic method to draw the internal force envelope diagrams of arbitrary continuous beams is established on the basis of the general expressions of the internal forces. The method and its corresponding computer program can be universally used for arbitrary multispan continuous beams that bear different kinds of dead loads and live loads: concentrated force, concentrated moment and uniform load.

Key words: Continuous beam, Intelligent software, Internal force envelope diagrams, Singularity function