Comparative seismic performance of building with Cu-Al-Be and Ni-Ti SMARB base isolation system using particle swarm optimization

ABSTRACT This study deals with the optimal performance of a five-storeyed shear frame building, base isolated with shape memory alloy rubber bearing (SMARB), under a set of real earthquake data. Nickel-Titanium (Ni-Ti) as well as Copper-Aluminum-Beryllium (Cu-Al-Be) is used as SMA material, and the responses are compared for both systems. The variations of optimized responses of the building are obtained for changing various structural and isolator parameters. A numerical study is taken where the optimization problem is considered to minimize the top floor acceleration by obtaining the optimal value of normalised forward transformation strength (F S0 ) of SMA using the particle swarm optimization (PSO) algorithm, which is an advanced bio-inspired optimization technique and relies on an intelligent swarm of particles which search for the solution in the problem space. The study shows that Cu-Al-Be-based SMARB system is more efficient than the traditional Ni-Ti-based base isolation system in reducing the top floor acceleration of the building at a marginal cost of isolator displacement. The optimal F S0 is considerably higher for Cu-Al-Be SMA device in practical conditions. Overall this study shows that Cu-Al-Be is a better choice for SMARB isolated buildings for mitigating seismic vibration compared to Ni-Ti SMARB system.