Research Spotlight: Loss-of-Stability vs Yielding-Type Collapse Mode in 3D Steel Structures Under a
2017 Annual Stability Conference Preview
Session S6 – Stability of Assemblages and Systems Thursday, March 23, 2017 10:15 am
Loss-of-Stability vs Yielding-Type Collapse Mode in 3D Steel Structures Under a Column Removal Scenario: an Analytical Method of Assessing the Collapse Mode
Progressive collapse of structures is the phenomenon of an initial failure mushrooming into global level, resulting in total or partial damage of the structure. Aiming to reduce the potential for progressive collapse, current guidelines have proposed a variety of design procedures. Among these, the threat-independent “alternate load path method” is most commonly employed, according to which a key-component is removed from the structural model and the capability of the remaining structure to withstand this loss is assessed. The current paper develops a detailed 3D numerical model of a prototype 10-story steel framed composite building and investigates its response as interior gravity columns are removed along the height of the structure at each floor individually in-turn. The primary focus of the study is the investigation of the correlation between the column removal location and the corresponding collapse mechanism. Two failure modes are taken into consideration, namely the “yielding-type” and the “stability” one. The former is a ductile mode associated with excessive vertical deformations of the beams and slabs above the column removal, while the latter is a brittle mode which manifests through column buckling. Numerical results clearly indicate that column removal scenarios at the lower part of the structure trigger the stability collapse mechanism, which is considered highly undesired. The importance of accurate connection modeling was highlighted and it was shown that even with very conservative connection modeling assumptions the stability mode is dominating the collapse after the removal of the ground floor column. The ultimate aim of the authors is the development of an analytical solution to describe the progressive collapse behavior of a 3D structure and ongoing research is focusing towards this direction.
Panos Pantidis and Simos Gerasimidis, University of Massachusetts, Amherst, MA