Multicriteria optimization of lightweight bridge structures with a constrained force density method

This paper deals with the preliminary shape design of three-dimensional bridge structures. For crossing wide spans, lightweight truss structures are well-suited. Due to their complex equilibrium state involving a geometrically nonlinear behaviour, the generation of an equilibrated system requires numerical form finding methods, namely the force density method for truss structures. To enforce geometric restrictions, a constrained force density method is developed. Then, the scope of the form finding method is extended to the search of optimal configurations by combining the force density method with multiobjective genetic algorithms within an integrated design process. Large scale applications illustrate the proposed strategy.