Study on numerical seismic performance evaluation of 3D building frame with smart self-centering BRBs system

Structures are generally designed to withstand the applied loads safely. However, in order to secure the stability of structures from earthquakes, which are unpredictable natural disasters, seismic damage reduction technology is required, and various technologies are being developed so far. Recently, to resist seismic loads, new materials are used to reinforce structural members, or technologies to control vibration by applying seismic devices are being developed. In particular, Shape Memory Alloy (SMA), also known as a smart alloy, has a unique re-centering capacity that exhibits a flag-shaped hysteresis curve, so when applied in a structural system, it can provide safer structural performance with higher serviceability. In this study, to prove the structural stability of the SMA buckling restrained brace (BRB) system to which the seismic isolation is applied, a study was conducted to evaluate the seismic performance according to the structural material, type, and device. Response of SMA BRB and base isolation system has been calibrated by following quasi-static and dynamic loading test and substantially matches empirical results. A prototype steel frame has been designed by following standard code which has a single-story basement assumed to be surround by well graded sandy soil. In addition, two different column system has been considered namely as, Hollow Steel Section (HSS) and Concrete Filled Steel Tubes (CFST). For the nonlinear dynamic analysis, two sets of 11 bidirectional artificial earthquakes were considered, and the interstory drift ratio (IDR) and residual interstory drift ratio (RIDR) were considered as main performance evaluation parameters. In moderate ground motion, the performance of the SMA BRB was found to be higher compared to the steel BRB and base isolation system due to its superior self-centering capacity. However, in strong ground motions, periodic damage degrades the performance of the SMA BRB, which was found to be nearly identical to the steel BRB, but still superior to the base isolation system. This performance evaluation study will help to understand design aspects of seismic protection systems for similar types of building frames.