Performance assessment under multiple hazards

Structural vulnerability and associated methodologies for its assessment have been identified as a key research field in structural engineering. Vulnerability itself can be defined in multiple ways and it can be evaluated using widely different formats that are typically inconsistent with each other, especially when considering different hazards. For example, it can be defined either deterministically or probabilistically, it can be based on the concept of one or more limit-states or performance levels and it can be evaluated using static or dynamic methods including or ignoring aleatory randomness and epistemic uncertainty. Thus, at least for frequent actions from well understood hazards such as wind, fire or snow, there are several methods to estimate it, some complex and other simplified, some of which are deeply entrenched in the professional practice, forming a cornerstone of past, current and forthcoming design codes and guidelines. On the other hand, infrequent actions from extreme natural hazards, such as floods, hurricanes, volcanoes, avalanches, tsunamis and earthquakes are often less well understood, and researching methodologies for their assessment is an ongoing project. With the emergence of multi-hazard assessment concepts, it is now important to collectively discuss such methods, understand their merits and attempt to cast them in a format that is suitable for integration within a single practical assessment framework. Therefore, in the sections to follow we will present a review of existing methodologies for structural vulnerability assessment under earthquake, tsunami and wind actions.