Energy-based Seismic Collapse Risk Assessment of Structures

Structural collapse is traditionally associated with the exceedance of a target value of inter-story drift or plastic hinge rotation at structural components. However, such an approach may not accurately estimate the structural collapse potential due to load redistribution and variation of structural damage within the structure. Moreover, collapse prediction may be sensitive to such assumed threshold values. Therefore, in this study, energy balance of a structural system is utilized to represent the severe structural damage history that eventually leads to structural collapse. Performing energy-based collapse analyses, a new dynamic-instability based collapse criterion is developed and key collapse measures are identified. Using the results, a new collapse fragility model is then established for estimating and improving structural reliability against collapse. Moreover, extensive parametric studies are performed to investigate sensitivity of collapse fragilities to variability in structural and earthquake parameters.