Loss Assessment of Unreinforced Masonry Buildings

Abstract eng:
Seismic risk is defined as the potential of negative consequences of hazardous events that may occur in a specific area unit and period of time. In particular, the outcome of a seismic risk analysis is the mean annual rate of specific consequences, for example economic loss, which is obtained by the probabilistic convolution of the three components: hazard, vulnerability and exposure. These types of analyses are increasingly directed to the evaluation of the socioeconomic consequences of the earthquake, which represent a critical aspect that requires more research than others components of risk, since in the past most of attention has been addressed to the hazard and vulnerability. For this reason, the paper provides a contribution for the assessment of economic losses in masonry buildings, that implies the definition of a methodology on how to pass from structural seismic response to a response in terms of losses, following a component-based approach from which the direct loss is calculated by summing the losses over all damageable components in the building (structural, non structural and contents). The losses can be defined according to different approaches: passing directly from the intensity measure to repair cost or passing through firstly, the fragility curves, that relates the intensity measure and the engineering demand parameter, and, secondly, the engineering demand parameter and loss functions to estimate the repair costs. The first derives from the definition of a cost function that takes into account the progressing of damage in each structural element and the possible consequence on the reparability of related parts in the building. The procedure proposed is applicable for the detailed assessment of a specific building. The different inherent uncertainties, both aleatory and epistemic, which are involved in the seismic risk assessment (hazard, seismic demand, structural capacity and loss evaluation) are considered in the procedure. It is applied to a three-story unreinforced masonry case study analyzed with two configurations of constructive details aimed to simulate and compare two different in-plane collapse mechanisms that can generate a different losses assessment. These buildings are modeled by the equivalent frame approach (piers and spandrel beams) and analyzed by nonlinear static (pushover) and dynamic analysis following the Multiple Stripe Analysis.

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