Energy flow in progressive collapse of steel framed buildings

This paper provides the methodology for an energy-based progressive collapse assessment of multistory buildings. The progressive collapse of steel-framed buildings is analyzed based on an energy flow perspective. The energy based assessment of structural members is introduced, and compared with conventional force and deformation approaches discussed in the literature. Consecutively, the advantages of energy flow analysis in interpretation of extreme dynamic events are discussed. On the global level, a building can arrest the collapse, and achieve its stable configuration only if the kinetic energy is completely dissipated by the structure. Otherwise, the remaining kinetic energy will cause the collapse to continue. In a conventional building, kinetic energy is dissipated within structural members by the transformation into their deformation energy. Structural members can dissipate finite amounts of energy before becoming unstable. The column deformation energy was shown to be a better stability indicator under dynamic loading than the maximum dynamic force. The energy flow analysis is illustrated with a collapse assessment of a typical steel building.