The Force Method

Abstract

Up to this point, we have focused on the analysis of statically determinate structures because the analysis process is fairly straightforward; only the force equilibrium equations are required to determine the member forces. However, there is another category of structures, called statically indeterminate structures, which are also employed in practice. Indeterminate structures require another set of equations, in addition to the force equilibrium equations, in order to solve for the member forces. There are two general methods for analyzing indeterminate structures, the force (flexibility) method and the displacement (stiffness) method. The force method is more suited to hand computation whereas the displacement method is more procedural and easily automated using a digital computer.