Improving seismic performance of base isolated structures with a hybrid U-shaped steel damper as an isolator

Current earthquake-resistant design standards emphasize structural resilience by accounting for inelastic behaviour during major seismic events, particularly in steel and reinforced concrete (RC) buildings. This approach typically achieves controlled ductile performance, albeit with some structural damage. To minimize such damage, passive control systems are widely adopted. This study explores an advanced seismic mitigation strategy for RC frame buildings by incorporating a hybrid damping system at the base, which combines a U-shaped damper (USD) with a rubber core functioning as an isolator. The U-shaped elements, constructed from steel and aluminium, are modelled with elastoplastic material behaviour. At the same time, the rubber core is defined using the hyper-elastic Ogden model, ensuring an accurate representation of its nonlinear properties. Strategically positioned at the building's foundation, the USD synergises with the rubber core to enhance damping efficiency and energy dissipation during seismic events. Nonlinear Time History Analysis under four distinct ground motion scenarios was employed to evaluate the structure's seismic performance equipped with the USD-based isolator. The findings reveal a significant improvement in the structure's capacity to endure seismic forces compared to a counterpart without the USD system, demonstrating its superior effectiveness in mitigating earthquake-induced damage.