Study Of Minimum Tie Force Requirements on the Progressive Collapse Resistance of Steel Braced Frames

Abstract

Progressive collapse is a structural phenomenon in which the failure of a single primary load-carrying element triggers a chain reaction of failures, resulting in partial or complete collapse of a building. To prevent such disproportionate damage, improving robustness, redundancy, and alternate load paths in high-rise steel structures is critical. This research presents an original nonlinear comparative study of Buckling Restrained Braced (BRB) frames and Eccentrically Braced Frames (EBF) subjected to column removal scenarios, following the provisions of GSA and DoD guidelines using ETABS software.

Three-dimensional analytical models with identical geometry, loading conditions, material properties, and boundary restraints are developed for both bracing systems to ensure consistent comparison. Nonlinear static (pushdown) and nonlinear dynamic analyses are carried out to examine structural response parameters such as vertical displacement, inter-storey drift, plastic hinge development, ductility ratio, and energy dissipation capacity. The investigation focuses on evaluating how effectively each system redistributes internal forces and limits collapse progression after the sudden removal of a critical column.

The analytical results indicate that BRB systems exhibit stable and symmetrical inelastic behavior with improved ductility and better displacement control, whereas EBF systems concentrate yielding within link beams, allowing efficient energy dissipation through controlled shear mechanisms. Overall, the study provides a clear technical basis for selecting suitable bracing configurations to enhance progressive collapse resistance and improve the overall resilience of high-rise steel buildings.