Variable Energy Ratio Method for Structural Design

Minimum weight design of trusses and frames by a method involving the maximization of the member energy ratios is treated. The energy ratio of a member is the ratio of the strain energy stored in a member when the structure is subjected to a particular load condition to that which could be stored in the member. A theorem which justifies the maximization of the energy ratios to minimize weight as well as heuristic algorithms to effect this maximization are presented. These algorithms have been tested using a number of truss and frame structures subjected to multiple static loads, simple harmonic dynamic loads, and considering stress, local buckling, and displacement constraints. The results indicate that the method is very effective in obtaining minimum weight designs of trusses and frames.