3,968 research outputs found
Seismic vulnerability of existing buildings:observational and mechanical approaches for application in urban areas
No full textPast and recent earthquakes have shown the high seismic vulnerability of old and historic down-town: the 2009 L’Aquila earthquake is one of the last dramatic examples, in which several historical centres (such as – besides L’Aquila - Onna, Castelnuovo, Villa Sant’Angelo,etc.) were severely struck, with heavy damages extended to the whole built-up areas and collapses of large portions (sometimes even of the totality) of many urban blocks. It follows the relevance of providing reliable vulnerability and risk analyses from the economic, cultural and life safety point of view. In this chapter, after some explanations on the damage levels and buildings type classification, some models to be used for vulnerability analyses are presented considering both the macroseismic and mechanical approaches and both unreinforced masonry (URM) and reinforced concrete (RC) buildings. In particular, in case of the macroseismic approach, the model proposed in Lagomarsino and Giovinazzi (2006) is discussed. In case of the mechanical one, the DBV-concrete and DBV- masonry (Displacement Based Vulnerability) methods proposed in Lagomarsino et al. 2010 have been adopted as reference; the DBV- masonry method starts from the model originally proposed in Cattari et al. (2005), whereas the DBV- concrete one from the DBELA method proposed in Crowley et al. (2004). In both cases, starting from the original formulations, some significant modifications have been introduced by the Authors
Analisi non lineari per la simulazione del danno di un fabbricato in San Felice sul Panaro (Emilia, 2012)
No full textNell’articolo è illustrata la simulazione numerica della risposta sismica di fabbricato sito in San Felice sul Panaro che ha subito danni significativi a seguito del terremoto che ha colpito l’Emilia nel Maggio del 2012. La simulazione è eseguita adottando l’approccio di modellazione a telaio equivalente tramite il software Tremuri (Lagomarsino et al. 2012) e svolgendo analisi non lineari statiche e dinamiche. Il confronto con il danno reale occorso e il potersi avvalere di una caratterizzazione della domanda sismica basata su registrazioni reali costituiscono un elemento fondamentale per potere validare i risultati ottenuti nonché, più in generale, l’attendibilità degli strumenti impiegati per la valutazione della sicurezza sismica del costruito in muratura. I risultati evidenziano una notevole accuratezza degli strumenti proposti nella capacità di previsione della risposta sismica
Damage assessment of churches after L’Aquila earthquake (2009)
No full textL’Aquila earthquake, which occurred on April 6, 2009, proved the high vulnerability of cultural heritage, with particular reference to churches. Damage assessment in the emergency was carried out on more than 700 churches with a methodology aimed at recognizing the collapse mechanisms in the different architectonic elements of the church. The method was developed after the earthquake in Umbria and the Marches (1997) and has been widely used in the last decade; this approach is also very useful for seismic prevention, as it allows one to single out the most vulnerable structures. Some examples are presented in this paper, representative of recurrent damage in the main elements of the church: the façade, the roof, the apse and the belfry. It emerges that, for a correct interpretation of damage and vulnerability, it is necessary a deep knowledge of local construction techniques and of the historic transformation sequence. Moreover, the bad behaviour of churches strengthened by modern techniques, such as the substitution of original timber roofs with stiff and heavy r.c. slabs, was observed. Starting from the observation of some case studies, the paper achieves some worth results, which may be useful for correctly driving future strengthening interventions
Mechanical models for the vulnerability assessment of existing reinforced concrete buildings
No full textVulnerability assessment at large scale requires referring to reliable models which are able to establish a
correlation between hazard and structural damage. Among the different approaches proposed in literature, the
attention is focused on mechanical models based on the displacement-based approach, which describe the
inelastic response of buildings by capacity curves able to provide essential information in terms of stiffness,
overall strength and ultimate displacement capacity. In the paper an extensive sensitivity analysis is carried out
by considering the various expressions proposed in literature for these entities (in order to define the more
reliable ones) and by evaluating how each parameter (e.g. strength and ductility of materials, structural element
dimensions, interstorey heigt, ...), which mechanical models may be founded on, affect the structural response (in
terms of main parameters which define the capacity curve). Particular attention is paid to the model adopted in
Lagomarsino et al. (2010) by proposing some improvements as pointed out from the sensitivity analyses results
Proposta di un aggiornamento della formulazione NTC-08 per gli spettri di piano e sua applicabilità nella verifica dei meccanismi locali
No full textLa valutazione della risposta sismica di un’appendice non strutturale o di una porzione strutturaleposti in quota o sommità rispetto alla struttura principale ètradizionalmente affrontata seguendo due approcci: i) il “Floor response spectrum approach”, che si basa sull’ipotesi di poter trascurare l’interazione dinamica tra i due sistemi ed opera per sottostrutture; ii) il “Combined Primary-Secondary system approach”, che studia il sistema nel suo complesso includendo esplicitamente gli effetti di accoppiamento. Nell’ambito del primo approccio, il problema si riduce alla corretta definizione dello spettro di piano, per il qualenumerose formulazioni analitiche semplificate sono proposte in letteratura ed adottate nelle normative nazionali ed internazionali. Tali espressioni includono tuttavia in alcuni casi la dipendenza da un numero molto limitato di parametri, non sufficiente a cogliere tutti gli aspetti fisici che possono influenzare il fenomeno di interazione. In questo contesto, l’articolo si pone due obiettivi: i) la verifica dell’attendibilità e la definizione dei campi di applicabilità delle tradizionali procedure per sottostrutture; ii) il confronto tra alcune formulazioni proposte in letteratura per gli spettri di piano e la proposta di un aggiornamento di quella proposta in Lagomarsino 2015(e da cui deriva la formulazione NTC-08), che si è dimostrata dal confronto quella più affidabile
Vulnerabilità e risposta sismica delle chiese aquilane: interpretazione del danno e considerazioni sul miglioramento strutturale
No full text
Seismic assessment of rocking masonry structures
No full textThe seismic assessment of rocking masonry structures is a complex task, due to the high sensitivity of the behavior to the characteristics of the input motion. The paper compares the results offered by different models and the reliability of widely used intensity measures. A displacement-based approach based on an incremental limit analysis of rigid blocks is proposed for the performance-based assessment of rocking masonry structures, such as: rocky structures (archeological remains, obelisks, columns, trilithons), arch-piers systems (e.g. triumphal arches, belfries), out-of-plane mechanisms of walls (standing out walls, façades in buildings or churches etc.) or artistic assets prone to overturn (pinnacles, statues etc.). The method is compatible with the format of the PERPETUATE performance-based assessment method for cultural heritage assets
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