Seismic Response Analysis of Knee-Braced Steel Frames Using Ni-Ti Shape Memory Alloys (SMAs)

Abstract

Shape Memory Alloys (SMAs) are known as active materials that can be widely used for structural purposes due to their flag-shape behavior under loading and reloading. Their unique characteristics provided a potential solution for civil engineers especially to model buildings with the capability of dissipating seismic energy. In this study, the main purpose is to explore the seismic behavior of Knee-Braced Frames (KBFs) and use SMA materials in the knee member as the reparable member that plays a crucial role in dissipating energy. For this aim, the four, eight, and twelve stories (i.e. 4-Story, 8-Story and 12-Story) structures with lateral resisting systems of Concentrically Braced Frame (CBF), Knee Braced Frame (KBF), and a KBF with SMA member (KBF-SMA) have been modelled using Opensees. To validate the modelling procedure of SMA members, ABAQUS software was used. Then, Incremental Dynamic Analysis (IDA) was performed for seismic response assessment of structures assuming Sa(T1) as intensity measure and maximum interstory drift ratio (IDR) and residual roof drift ratio (RIDR) as Engineering Demand Parameters (EDPs). The results showed that the KBF-SMA system decreased the RIDR by 32.34% at given Sa(T1) from 0 to 2(g), and 41.79% at given Sa(T1) from 2 to 4(g), respectively, compared to the values of CBF system. In addition, compared to the values of the KBF system, the RIDR decreased by 22% at given Sa(T1) from 2 to 4(g), and 87.18% at given Sa(T1) from 4 to 6(g), respectively.