Composite Floor Systems under Column Loss: Collapse Resistance and Tie Force Requirements

This paper presents a computational assessment of the performance of steel gravity framing systems with single-plate shear connections and composite floor slabs under column loss scenarios. The computational assessment uses a reduced modeling approach, while comparisons with detailed model results are presented to establish confidence in the reduced models. The reduced modeling approach enables large multibay systems to be analyzed much more efficiently than the detailed modeling approaches used in previous studies. Both quasistatic and sudden column loss scenarios are considered, and an energy-based approximate procedure for analysis of sudden column loss is adopted after verification through comparisons with direct dynamic analyses, further enhancing the efficiency of the reduced modeling approach. Reduced models are used to investigate the influence of factors such as span length, slab continuity, and the mode of connection failure on the collapse resistance of gravity frame systems. The adequacy of current structural integrity requirements is also assessed, and based on the computational results a new relationship is proposed between the uniform load intensity and the tie forces required for collapse prevention. (C) 2014 American Society of Civil Engineers.