A 2-STEP METHOD FOR THE OPTIMUM DESIGN OF TRUSSES WITH COMMERCIALLY AVAILABLE SECTIONS

A two-step method is presented for the optimum design of trusses with available sections under stress and Euler buckling constraints. The sh ape design of the truss is used as a means to convert the discrete sol ution into a continuous one. In the first step of the method, a contin uous solution is obtained by sizing and shape design using an approxim ate polynomial expression for the buckling coefficients. In the second step, the member sizes obtained are changed to the nearest available sections and the truss is reconfigured by using the exact values for t he buckling coefficients. The optimizer used is based on the sequentia l quadratic programming and the gradients are evaluated in closed form . The method is illustrated by two numerical examples.