Author(s)

Alvaro F.M. Azevedo

Abstract

In this paper an integrated formulation for the structural optimization of frames with nonlinear material behavior is presented. Member sizes, generalized displacements and internal forces are treated as variables of the nonlinear program. The objective function is the cost of the structure. Equilibrium equations and plastic hinge complementary conditions are treated as equality constraints. Stresses, displacements and plastic hinge rotations may be limited. Plastic hinges are automatically located in the most critical position. The nonlinear program is solved by a second-order Lagrange-Newton algorithm. The computer implementation parses all the expressions and calculates first and second derivatives of the Lagrangian. The sparsity of the Hessian matrix is taken into account and several nu

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