Title: Isolamento e controllo attivo nella progettazione fondata sulla minimizzazione delle perdite 

Abstract: Performance-based design was first envisaged in the early 1990s and has become a mantra in conceptual seismic design. However, practical approaches to be possibly introduced in codes of practice are not readily available, to say the least, though some can be found in the literature. What is essentially missing is some correlation between structural response parameters and expected monetary losses, at a level of simplicity comparable with the force- or displacement-based approaches applied to designing in everyday practice. The basics of a formulation that may evolve into such a practical loss–based approach will be discussed, with a focus on some essential practical questions: is it possible to design for very low expected loss and what will be the associated parametric investment cost? 

In this context, seismic isolation plays a peculiar role, being one of the most accredited candidates to allow a credible design approach for strategic constructions, in which case extremely contained losses could be aimed at, even for low probability ground motions. Some examples derived from the recent 2023 Turkey earthquake will be introduced and discussed as case studies. 

The potential application of active control for the same purpose will be briefly touched. This technology is still in its infancy but seems to be promising in specific areas of application. 

Title: Ricostruire l’Appennino Centrale tra Innovazione e Sicurezza

Abstract: Il territorio italiano ha un primato assoluto in Europa: quello della maggiore sismicità continentale. Su 1.300 terremoti distruttivi di cui si ha memoria e documentazione nel secondo Millennio, nell’area del Mediterraneo, almeno 500 hanno interessato il nostro Paese. Insomma, l’Italia è un Paese quasi totalmente esposto al rischio sismico, cambia solo la frequenza attesa e la potenza liberata.

La ricostruzione da un terremoto costa in genere circa 10-100 volte di più che realizzare un adeguamento o un miglioramento antisismico. Dal terremoto del Belice in poi si stima che le ricostruzioni post sisma siano costate fino a 200 miliardi, senza contare i danni economici indiretti. 

È la prima volta che, nell’ambito di una ricostruzione post sisma di vasta portata come quella dell’Italia Centrale (la sequenza sismica 2016-2017 ha interessato un’area di 8000 kmq, distruggendo edifici per un valore di circa 28 miliardi di euro), viene pianificato un lavoro di analisi sistematica, con controlli sul campo e l’uso di tecnologie avanzate sulle aree di dissesto individuate. 

Ricostruire in sicurezza vuol dire aver sciolto definitivamente quella visione datata e irrealistica della ricostruzione “dov’era, com’era”. Dopo le indicazioni univoche offerte dalla conferenza di Sendai oggi l’attenzione si è spostata, opportunamente, sulla necessità di migliorare la comprensione del rischio di disastri in tutte le sue dimensioni di esposizione, vulnerabilità e caratteristiche di pericolosità; la responsabilità per la gestione del rischio di disastri deve avere l’obiettivo di "ricostruire meglio", laddove sia possibile e sicuro farlo. 

Nella ricostruzione in atto nel più grande cantiere edile d’Europa abbiamo due “case histories” all’avanguardia: Arquata del Tronto e Castelluccio di Norcia. Due esempi di questo innovativo percorso di messa in sicurezza prima di ricostruire. Due progettazioni ormai diventati oggetto di studio in Italia e all’estero.

Title: Large Ship Impacts on Bridge Piers

Abstract:The Key Bridge in Baltimore stood for more than half a century until it collapsed when a massive ship it was never designed to withstand collided with it. Ship collision design provisions established in 1991, well after the bridge was built, suggest that the chance of collision was extremely low, estimated to be around 1/100,000. This risk assessment, which ultimately proved to be overly optimistic, likely contributed to a false sense of security about the bridge’s vulnerability and may have impeded proactive measures to reinforce the structure.  Collapse of this bridge also highlighted the need for critical investigation through complex simulations using impact of large ships into bridge piers to determine the sufficiently of current AASHTO guideline and development of simulation tools to investigate safety of bridge piers from large ship impacts.  This presentation will highlight various critical aspects of the impact of large ships on bridge piers.

Title: Bradiseism and volcanic hazard at Campi Flegrei, Italy

Abstract: The Phlegraean Fields (Campi Flegrei) are a volcanic caldera formed by the eruptions of the Campanian Ignimbrite (39,000 years ago) and the Yellow Tuff (15,000 years ago). Subsequently, three periods of activity can be distinguished, during which about 70 eruptions occurred, separated by long periods of quiescence. The most recent eruption took place in 1538, and it is well documented through images and historical documents. The typical hazardous eruptive phenomena include the generation of pyroclastic flows, the dispersal and fallout of volcanic ash, and lava flows. More recently, the "bradyseism risk" has been officially recognized, referring to ongoing ground deformation and associated earthquakes in the area. An additional hazard that is now being discussed is the potential occurrence of phreatic explosions, which may be triggered by the rapid depressurization of shallow portions of the hydrothermal system. The presentation will illustrate the various hazards related to the possible opening of new eruptive vents and volcanic eruptions, as well as the damage associated with seismic activity, ground deformation, and gas emissions that occur during bradyseismic crises, such as the one that has been ongoing since 2005.

Title: Performance of Seismically Isolated Structures in Earthquakes.

Abstract: many seismically isolated structures have been constructed, ranging from houses, apartment buildings, hospitals, emergency facilities, architecturally and historically significant structures and tall buildings to large bridges and offshore platforms.  The observation of performance of such structures in earthquakes provides valuable information on the validity of design procedures and on the lifetime behavior of isolators and delivers lessons on actions that are needed to avoid problems and enhance reliability.

The presentation will start with a discussion of design procedures for seismically isolated structures, uncertainty and reliability in design.  This guides the audience to a better understanding of the observed performance of several seismically isolated structures that are presented next.  It is concluded that, in general, the performance of seismically isolated structures is very good but dependent on proper analysis and design, provisions for increased capacities of isolators and superstructures to meet reliability objectives, effective peer review, testing (prototype and production) of isolators, proper construction and inspection.