1,721,338 research outputs found
Probabilità e salti mortali: le insidie della validazione della analisi di pericolosità attraverso l'occorrenza di singoli terremoti
No full textPerformance-Based Earthquake Early Warning
No full textSignificant investments are undergoing internationally to develop earthquake early warning (EEW)
systems. So far, reasonably, the most of the research in this field was lead by seismologists as the issues
to determine essential feasibility of EEW were mainly related to the earthquake source. Many of them
have been brilliantly solved, and the principles of this discipline are collected in the so-called
real-time
seismology
. On the other hand, operating EEW systems rely on general-purpose intensity measures as
proxies for the impending ground motion potential and are suitable for population alert. In fact, to date,
comparatively little attention was given to EEW by earthquake engineering, and design approaches for
structure-specific EEW are mostly lacking. Applications to site-specific systems have not been
extensively investigated and EEW convenience is not yet proven except a few pioneering cases,
although the topic is certainly worthwhile. For example, in structure-specific EEW the determination of
appropriate alarm thresholds is important when the false alarm may induce significant losses; similarly,
economic appeal with respect to other risk mitigation strategies as seismic upgrade should be assessed.
In the paper the least issues to be faced in the design of engineering applications of EEW are reviewed
and some work done in this direction is discussed. The review presented intends to summarize the
work of the author and co-workers in this field illustrating a possible
performance-based
approach for
the design of structure-specific applications of EEW
Probabilities and Fallacies: Why Hazard Maps Cannot Be Validated by Individual Earthquakes
No full textIn countries with an advanced seismic technical culture, where best-practice hazard studies (which are therefore necessarily probabilistic) are available, the occurrence of a damaging event often triggers a debate, which is as understandable as it is delicate, aimed toward the verification and/or validation of the ground motion intensity estimates provided by the official hazard maps. Evaluations such as these are typically based either on the comparison of elastic response spectra derived from records of the event in question with uniform hazard (design) spectra, or on superimposing ground motion intensity measures on available hazard curves to retrieve the return period to which they correspond. This short note, using the recent 2012 Mw 6.0 Emilia (Italy) earthquake, discusses a few arguments, according to which this type of exercise should take into account the implications inherent in the probabilistic nature of hazard analyses, in order to avoid the risk of drawing conclusions that may be misleading or that may be likely to cause misconceptions about rationality of the current approach to seismic hazard
Foreword to the Special Issue for the 2019-2021 RINTC (The Implicit Seismic Risk of Existing Structures) Project
No full textThis special issue of Journal of Earthquake Engineering (JEE) follows a previous one from 2018,
which dealt with the results of a research project performed between 2015 and 2017, whose
acronym was RINTC, and aimed at evaluating the seismic reliability of code-conforming
structures in Italy (Iervolino and Dolce 2018). The need for research on this topic, and its
international value, come from the well-known fact that in most building codes, applying multi-
limit-state-based design (sometimes also referred to as a simplified version of the performance-
based design), the structural reliability is not explicitly controlled, and ultimately it is unknown.
This happens even if the ground motion intensity is determined based on the limit state
considered in the design and the corresponding exceedance return period from the probabilistic
seismic hazard analysis (PSHA) for the construction site
Earthquake Engineering by the Beach, A Relaxed Workshop on Performance-Based Earthquake Engineering
No full text
Hazard, ground motions, and code-based structural assessment: a few proposals and yet unfulfilled needs
No full textCode-based structural assessment via nonlinear dynamic analysis requires seismic input believed to be a representation of the seismic threat to the site with respect to the limit-state of interest. Codes often are only slightly more specific than that, except prescribing to match a design spectral shape. Therefore, in record selection, several options, hearsays and beliefs may render the job especially hard for the analyst or, on the other side, heuristically simple, yet potentially inadequate to the scope. This paper, given the current European codes’ procedures, tries to discuss some tools which may help to address some basic issues related to seismic input selection. In fact, some recent achievements are reviewed first, these include: automated selection of real record sets; design earthquake maps from hazard disaggregation; conditional hazard maps to include secondary ground motion intensity measures (IMs) in definition of seismic action; and the use of alternate types of spectrum matching records. Furthermore, possible advancements, desirable to be accounted for by future codes, are also discussed: advanced ground motion IMs, and near-source pulse-like records. Only hints are given herein, while pointing to other papers most of them presented at this same conference
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