Blast Performance of Steel Frames Equipped with NiTi SMA Bolts: Design Procedure and Numerical Evaluation

Abstract

This study evaluated the performance of smart steel moment-resisting frame structures (MRFs) equipped with nickle titanium shape-memory alloy (NiTi SMA) connection systems subjected to blast overpressure. A total of five NiTi SMA–based connections were designed conforming to current European standards, and their numerical models were developed. To study the effect of number of parameters, e.g., section profiles, bolt diameter, and bolt preload, a parametric study has been conducted on NiTi SMA–based connections. The numerical models were validated against experimental data, and key design procedures have been proposed. A simplified Kingery blast calculation framework was adapted to determine the blast reflected overpressure profile. The strength of the NiTi SMA bolts and steel components were adjusted due to a high strain rate of blast loading. Four MRFs equipped with a NiTi SMA–based connection were designed with different heights. Global-level transient analyses were performed on the MRFs subjected to blast overpressure. The results showed that in addition to relatively large maximum interstory drift ratio, the NiTi SMA–based connections significantly reduced the residual interstory drift ratio compared with the steel bolted connection system counterpart. The results also revealed that the proposed key design procedures are essential to emphasize the role of NiTi SMA bolts.