Performance of steel moment resisting frames with RBS connections under fire loading

• Finite element analyses of steel frames with RBS connections under fire loading were conducted.
• The global behavior and local response of the frames under single bay fire were evaluated.
• The global response shows small shear forces developing at the basement level of frames.
• The global stability of the frames is not affected by single bay fire exposure.
• Localized behavior includes large axial forces, mid-span deflection, and column buckling.

Understanding the behavior of steel frames under fire loading is critical since many recent events have demonstrated the vulnerability of steel frames to such hazard. Extensive numerical and experimental studies have been performed to investigate the behavior of various types of individual steel structural members, connections, and frames under fire conditions. However, the response of steel moment resisting frames with Reduced Beam Section (RBS) connection has not been previously studied under fire conditions. In this paper, a set of numerical models are developed and analyzed to assess the performance of low-, medium-, and high-rise moment resisting frames with RBS connection under single bay fire exposure. Global system response and local behavior of the heated beams, columns, and RBS connections are considered. The analyses demonstrate that global stability of the steel frames is not affected by single bay fire exposure. However, large axial force and deflection in the beams, yielding in the RBS connections, and buckling in the columns are observed at elevated temperatures. The results of the analyses can aid engineers in understanding the local and global response of steel moment resisting frames with RBS connection under fire loading.