Fragility curves for tsunami loading

Abstract

Vulnerability to structural damage can be characterized by a fragility curve, which is expressed as the conditional probability of reaching or exceeding a particular damage state, expressed by a lognormal cumulative probability distribution, given a certain value of the demand parameter. Such curves have been produced for a variety of damage states in different categories of buildings that have been subjected to tsunami loading in different parts of the world, with the demand parameter taken as inundation depth. Harmonization was sought across these studies with respect to the median inundation depths. Three categories of buildings were identified based on construction material; namely reinforced concrete, masonry and timber. The median inundation depths for the complete damage state decreased from reinforced concrete (5.4-7.3m) through masonry (2.3-2.5m) to timber (~1.6m) structures. The steeper fragility curves for the weaker structures suggest that they display a single failure mode, probably sliding. The fairly narrow ranges above represent a number of different studies and indicate that a common family of curves can be used in damage assessments worldwide. Such ranges were identified for two partial damage states too.