Progressive Collapse Analysis of Steel Moment Frames: An Energy-Based Method and Explicit Expressions for Capacity Curves

Abstract

This paper presents a simplified model to evaluate progressive collapse response of steel beam–column substructures in a midspan column removal scenario. The model accounts for the influence of the span:depth ratio of the beam on progressive collapse behavior of substructures. The model was carefully validated against results obtained from rigorous numerical analyses. A single-story analogy was proposed to derive explicit expressions for progressive collapse–resisting capacity curves based on the energy conservation principle. The expressions covering the full range of loading—including interaction between the bending moments and beam axial load—and problem variables likely to be encountered in practice were derived. These explicit expressions can be applied in a step-by-step manner for tracing nonlinear behavior up to failure.