Optimality Criteria Method for Building Frames

An automated procedure is presented for the optimum design of large frameworks having size, stress and displacement constraints. The main feature of the algorithm is the use of a simple redesign procedure that is based on a generalized optimality criterion derived directly from the Kuhn-Tucker conditions. These conditions define an algorithm for the selection of improved designs for building frames in addition to being the necessary test for optimality. In addition, displacement and stress constraint derivatives are derived for multi-variable elements with several stress components. The energy-based approach for calculating behavior gradients has been extended to include the stess gradients for members of rigid plane frames. This formulation permits gradients to be determined for little cost and thus it complements the efficiency of the new generalized optimality criteria method. The efficiency of the complete algorithm has been demonstrated by optimizing the design for two relatively large frameworks, one having 30 members and the other 105 members.