Analisi dei possibili approcci alla valutazione delle frequenze di rilascio da auna tubazione a seguito di Sisma

Convegno VGR 200

Seismic protection of costructed facilities: optimal use of resources

The problem is tackled of the allocation of the resources assigned for upgrading an ensemble of buildings or other constructed facilities, whose seismic reliability is not considered sufficient. The resources are allocated in order to minimize the predicted value of either the economic losses, the number of endangered persons or the risk of severance of a network. The optimization procedure, although formulated in general terms, is illustrated with reference to simple examples, in which realistic values are attributed to the relevant parameters. These examples refer to masonry buildings, whose damages can be summed with each other to obtain the total damage of the ensemble, and to a highway network, whose critical elements are reinforced concrete bridges. The presence of several discrete quantities and discontinuous relationships requires the use of specific algorithms, and in particular of dynamic programming

Sperimentazione in galleria del vento di elementi strutturali per l'arredo urbano

Il crescente interesse per l’analisi della risposta all’azione del vento degli oggetti di arredo urbano è giustificato da motivi non solo di sicurezza, ma anche economici, entrambi legati al comportamento in condizioni di vento forte. Al momento mancano adeguati riferimenti normativi sulla caratterizzazione del campo di vento in ambiente urbano, ove, oltre all’effetto della rugosità media delle aree circostanti, è essenziale valutare gli effetti locali di schermo o di amplificazione della velocità media del flusso e le modifiche alla turbolenza provocate dalla presenza di ostacoli. Per ovviare a tale lacuna, è stata intrapresa una campagna di prove sperimentali presso la galleria del vento del CRIACIV a Prato; in questa memoria si riferisce sulla sperimentazione in scala 1:100 del modello strumentato di un elemento di segnaletica “a portale”, inserito in un quartiere urbano caratterizzato da un reticolo edilizio regolare

Optimal allocation of resources in reduction of the seismic risk of highway networks

The optimization of preventive upgrading interventions on the bridges of a highway network in an earthquake prone area is tackled. The bridges are assumed to be the vulnerable elements of the network, whose main purpose is to connect two sites. If the probability of collapse of each bridge under an earthquake of given intensity is known, the topology of the network allows us to calculate its reliability, i.e., the probability of maintaining the connection between the source node and the destination node. To increase the reliability, preventive upgrading interventions must be designed: the main purpose of this study is to present a procedure, based on dynamic programming, which is able to distribute the interventions among the bridges so that, for a given total amount of employed resources, the increase in reliability is maximized. The applicability of the procedure is demonstrated by some complete numerical examples. Alternative choices of the objective function and other further developments are also discussed