Simulation of seismic collapse of simple structures with energy-based procedures

Characterization of structural collapse is one of the key components of performance based earthquake engineering (PBEE) design. Usually, in seismic codes, the point of dynamic structural collapse due to earthquakes is based on parameters approaching subjective threshold values. Instead, energy-based formulations have raised as a more physical and robust approach in understanding the balance between the seismic energy input into the systems and the structural energy dissipated. In this paper a comparison between different energy-based methodologies is shown. Particularly, the formulation of a kinetic energy-based methodology is proposed and compared with the gravitational and intrinsic energy-based procedures, and with the results of the pushover analysis. The results show that the collapse state evaluated with the kinetic energy-based criterion is compatible with gravitational energy-based collapse technique in which its results were verified through some experimental tests. While in gravitational energy based method the amount of gravitational force should necessarily be significant, the proposed kinetic energy procedure predicts collapse point regardless of gravitational force. It also predicts local damage and hinge formation reasonably. The methods were investigated using single-degree systems (SDOFs) and a three story steel frame. According to outcomes, the proposed procedure can be used as an acceptable method for determination of collapse time, drift, and local damage.