Controlling Out-of-Plane Buckling in Shear-Acting Structural Fuses through Topology Optimization

Abstract

Shear-acting structural fuses rely on steel plates subjected to in-plane lateral displacements that dissipate energy through shear yielding or may have cutouts that result in shear or flexural yielding of ductile local mechanisms. However, the relatively high slenderness of the plates makes them prone to buckling, reducing the strength and energy dissipation capacity. The current study aims to facilitate local yielding mechanisms in shear structural fuses while resisting buckling. First, a genetic algorithm is implemented to find optimized topologies for structural fuses with a square domain and constant thickness. An objective function is formulated using the elastic shear buckling load obtained from a 3D eigenvalue analysis and the shear yield load obtained from a material nonlinear, but geometrically linear 2D plane-stress analysis. The ratio of shear yield load divided by shear buckling load is used as a way to control the amount of yielding expected before buckling. The set of new optimized topologies are interpreted into smooth shapes and analyzed using finite element models to evaluate their effectiveness. The finite element simulations show that the optimized geometries can resist buckling through inelastic displacement cycles with up to five times larger displacements than those that cause buckling in previously studied structural fuse shapes.