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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Seismic experimental analyses and surrogate models of multi-component systems in special-risk industrial facilities

Nardin, Chiara 22 December 2022 (has links)
Nowadays, earthquakes are one of the most catastrophic natural events that have a significant human, socio-economic and environmental impact. Besides, based on both observations of damage following recent major/moderate seismic events and numerical/experimental studies, it clearly emerges that critical non-structural components (NSCs) that are ubiquitous to most industrial facilities are particularly and even disproportionately vulnerable to those events. Nonetheless and despite their great importance, seismic provisions for industrial facilities and their process equipment are still based on the classical load-and-resistance factor design (LRFD) approach; a performance-based earthquake engineering (PBEE) approach should, instead, be preferred. Along this vein, in recent years, much research has been devoted to setting computational fragility frameworks for special-risk industrial components and structures. However, within a PBEE perspective, studies have clearly remarked: i) a lack of definition of performance objectives for NSCs; ii) the need for fully comprehensive testing campaigns data on coupling effects between main structures and NSCs. In this respect, this doctorate thesis introduces a computational framework for an efficient and accurate seismic state-dependent fragility analysis; it is based on a combination of data acquired from an extensive experimental shake table test campaign on a full-scale prototype industrial steel frame structure and the most recent surrogate-based UQ forward analysis advancements. Specifically, the framework is applied to a real-world application consisting of seismic shake table tests of a representative industrial multi-storey frame structure equipped with complex process components, carried out at the EUCENTRE facility in Italy, within the European SPIF project: Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities. The results of this experimental research campaign also aspire to improve the understanding of these complex systems and improve the knowledge of FE modelling techniques. The main goals aim to reduce the huge computational burden and to assess, as well, when the importance of coupling effects between NSCs and the main structure comes into play. Insights provided by innovative monitoring systems were then deployed to develop and validate numerical and analytical models. At the same time, the adoption of Der Kiureghian's stochastic site-based ground motion model (GMM) was deemed necessary to severely excite the process equipment and supplement the scarcity of real records with a specific frequency content capable of enhancing coupling effects. Finally, to assess the seismic risk of NSCs of those special facilities, this thesis introduces state-dependent fragility curves that consider the accumulation of damage effects due to sequential seismic events. To this end, the computational burden was alleviated by adopting polynomial chaos expansion (PCE) surrogate models. More precisely, the dimensionality of a seismic input random vector has been reduced by performing the principal component analysis (PCA) on the experimental realizations. Successively, by bootstrapping on the experimental design, separate PCE coefficients have been determined, yielding a full response sample at each point. Eventually, empirical state-dependent fragility curves were derived.
2

Shake table Seismic Performance Assessment and Fragility Analysis of Lightly Reinforced Concrete Block Shear Walls

Mojiri, Saeid January 2013 (has links)
<p>This thesis reports on shake table tests on fully-grouted reinforced masonry (RM) shear walls. The test walls covers a range of design parameters to facilitate benchmarking, a thorough performance investigation, and calibration of numerical models as well as development of fragility curves within the context of Performance Based Seismic Design (PBSD). The details of the experimental program undertaken, including general observations in terms of cracking patterns and failure modes of the tested walls and the results on the lateral strength, hysteretic response, dynamic properties, and the contribution of different displacement components to the response of the walls, are presented. More detailed analyses include seismic performance quantification of the walls in terms of inelastic behaviour characteristics, various energy components, and the effective dynamic properties of the tested walls. The analysis is concluded with development of simplified nonlinear response history analytical models and seismic fragility assessment tools for the tested walls. In general, the study results indicated that the displacement ductility capacity of the RM walls and their capability to dissipate energy through plastic hinging are higher than what is currently recognized by the National Building Code of Canada (NBCC). The fragility assessment study further indicated that similar walls are expected to conform to the current drift limits of the NBCC even at high seismic regions in Canada. The results of this study are expected to contribute to the growing Seismic Performance Database (SPD) of RM Seismic Force Resisting System (SFRS), and to the understanding of the lightly reinforced masonry wall system behaviour.</p> / Master of Applied Science (MASc)

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