Method of Combining Mechanisms in Plastic Analysis

Given the collapse load for the independent mechanisms of a structure, the failure load of the combined mechnisms can be obtained by superposition if hinge cancellations are noted. Although this method has been presented previously, a modified type of solution is presented herein and an example is given. This simplified method gives a better understanding of the actual process of combining independent mechanisms and the resulting combined mechanism thereof. Superposition is valid for any number of component independent mechanisms. In the simplification presented, an equation is written for each location of desired plastic hinge cancellation in the combined mechanism. In this "consistent deformation" type of solution, each independent mechanism will bemultiplied by a suitable factor which is obtained from the equations. The collapse load of a combined mechanism composed of four independent mechanisms is found as an illustration of the method.