Topology Optimization of Steel Shear Fuses to Resist Buckling

Shear-acting structural fuses are steel plates subjected to in-plane lateral displacements during extreme loading events such as earthquakes, that dissipate energy through localized shear or flexural yielding mechanisms. Although previous studies have reported that fuses with specific geometry can develop a stable hysteretic behavior, their small thickness makes them prone to buckling which reduces strength and energy dissipation capacity. In this work, topology optimization using a genetic algorithm is performed to find optimized shapes for structural fuses to yield while resisting buckling. The objective function uses the fuse's shear buckling load (VB) obtained from an eigenvalue analysis, and shear yield load (VY) obtained from a material nonlinear, but geometrically linear 2D plane stress analysis. The two types of analysis are shown to be computationally efficient and viable for use in the optimization routine. A new set of optimized topologies are obtained, interpreted into smooth shapes, and analyzed to evaluate their effectiveness. The computational results show that the optimized topologies present a stable hysteretic behavior through cycles of large drift angles with well localized yielding mechanisms.

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