Polidoro, Barbara (2014) Some seismic-cluster-based models for risk analysis of structures. [Tesi di dottorato]

Preview

Text Polidoro_Barbara_26.pdf Download (2MB) | Preview

Collection description

This thesis focuses on some time-variant aspects having an impact the seismic hazard and analysis on the life-cycle assessment of structures. Probabilistic seismic hazard analysis (PSHA), is usually computed through the homogeneous Poisson process (HPP), which is a stationary-increment memory-less model. However, when a single fault is of concern and/or the time scale is different from that of the long term, other models may be more suitable to represent the random earthquakes generation. Hence, after Chapter 1, which is the introduction, Chapter 2, provides a brief review of the most important assumptions of some history-dependent processes, which may be used for seismic hazard assessment. Attention is focused on renewal processes, which are usually adopted when characteristic earthquakes are of concern, that is, when it is assumed that the considered source tends to produce characteristic magnitude events and, on other models which also allow to include a relationship between the time and the magnitude of the earthquake (both are considered as random variables). Traditional PSHA only refers to the occurrence of mainshocks, that is, prominent magnitude earthquakes possibly identified within a sequence of events concentrated both in space and time (i.e., clusters). Within the sequence, according to some models, aftershocks may be seen as triggered by the mainshock. On this basis, some authors developed the aftershock-PSHA to evaluate the aftershock hazard expressed in terms of rate of exceedance of a ground motion intensity measure threshold. Starting from these studies, in Chapter 3, it is shown how it is possible to analytically combine results of PSHA and APSHA to get a probabilistic seismic hazard analysis for mainshock-aftershocks seismic sequences (SPSHA). Finally, still accounting for the effect of the whole cluster, in Chapter 4, a stochastic life-cycle damage accumulation model for earthquake resistant structures is developed. In particular, it is assumed that the occurrence of earthquake clusters is regulated by a HPP characterized by the same rate considered for the mainshocks. Within the cluster, mainshocks follow a HPP while aftershocks follow a NHPP according to APSHA. The model also accounts for the fact that the structure may suffer damage both in the mainshock and in the following aftershocks and that not all events are strong enough to damage it. It is also added the case in which damage in a single cluster is susceptible of gamma and inverse Gaussian representation whose reproductive property allows a closed- and/or approximate-form solutions for absolute and conditional reliability problems.

Downloads

Actions (login required)

View Item