Hybrid U-shaped steel dampers for advancing seismic isolation in building structures

Abstract

Modern seismic design codes prioritize structural resilience by accommodating inelastic deformation, especially in steel and reinforced concrete (RC) buildings. While this approach allows for ductile behaviour under strong earthquakes, it often results in structural damage. To reduce such damage, passive energy dissipation systems are increasingly utilized. This study introduces an innovative base isolation technique for RC frame structures, employing a hybrid U-shaped damper that integrates steel, shape memory alloy (SMA), and a rubber core. The U-shaped components, made from steel and SMA, exhibit elastoplastic and super elastic behaviour, respectively, enhancing energy absorption and self-centring capabilities. The rubber core, modelled using the hyper elastic Ogden formulation, contributes flexible isolation and nonlinear damping. Positioned at the base, the hybrid system enhances seismic performance by combining the isolating properties of rubber with the damping and recentring benefits of steel-SMA elements. Nonlinear time history analyses using four earthquake records confirmed that the hybrid isolator significantly reduces structural responses compared to systems without it.