Figures of and come from two basic structures in force method

In traditional teaching of force method in structure mechanics, it is needed to carry on at the same basic structure regardless of establishment of fundamental equation or the solution of coefficients and the free items in equations. However, it is shown in this paper that force method could simultaneously solve questions of statically indeterminate structures based on two different basic structures and simplify the calculation process. Through calculation and comparison, the physical and scientific significance are explained with overlay method when two basic structures selected are different. Using this method in teaching is helpful for students to understand the force method deeply.