On the 6th of April 2009, a devastating earthquake struck L’Aquila causing the partial collapse of the S. Maria di Collemaggio Basilica, one of the most important church in the area in terms of historical and artistic value. Among the serious damages that could be observed, the 12th-century nave’s columns showed serious cracking throughout their height. Therefore, a retrofitting intervention was planned with the two purposes of, first, enhancing the seismic structural behavior of the columns and, second, protecting these valuable elements from future additional damages. In this work, the procedure aimed at unloading the columns in order to allow the restoration intervention is described and analyzed stage by stage. The mentioned procedure had two crucial requirements: first, altering as less as possible the existent state of stress and, second, be easily executed at the construction site. In order to assess the first condition, a 3D FE model of the colonnade and the supported wall has been realized and a construction stage non-linear analyses implemented. The geometry was modeled through the acquisition of the results of a laser scanner survey in order to reflect faithfully the Basilica’s irregularities (lack of verticality of the wall, eccentricities, different dimensions from one column to the other..). Moreover, elastic-brittle constitutive laws were assigned to the model’s materials to reproduce the intrinsic non-linearity of the masonry. The results of the analyses have been attentively analyzed, monitoring the eventual occurrence of cracks or excessive displacements. The stresses, throughout the whole procedure, never exceed the materials’ ultimate strengths. To validate the model, a comparison between the numerical results and the values measured during the intervention has been executed. An acceptable deviation between the values was observed and, therefore, the reliability of the model was assured. Furthermore, the construction site phases of the renovation intervention have been described in detail.
La Basilica di Collemaggio, monumento di inestimabile valore artistico storico e religioso, è stata duramente colpita dal sisma dell’Aquila, verificatosi il 6 Aprile 2009, che ne ha provocato il crollo parziale. Tra gli elementi strutturali fortemente danneggiati, si trovano le colonne in pietra della navata centrale che presentano fratture lungo tutta la loro estensione. Un intervento di recupero e rinforzo strutturale è stato quindi pianificato col duplice obiettivo di preservare il valore delle colonne, originali del 1200 d.C., e al contempo, aumentarne la capacità resistente. In questo elaborato, l’intervento, comprendente lo scarico delle colonne, il restauro e la successiva fase di ricarico, è descritto in dettaglio e analizzato fase per fase. E’ stato realizzato un modello 3D a elementi finiti del colonnato per poter eseguire un’analisi per fasi e monitorare l’andamento di sforzi e spostamenti durante l’intero processo. La geometria del modello è stata ricavata da un rilievo laser-scanner in modo da poter riprodurre il più fedelmente possibile le irregolarità. Inoltre, agli elementi in muratura e pietra sono stati assegnati legami costitutivi di tipo elasto-fragile con limitata resistenza a compressione per rispecchiare la non-linearità intrinseca dei materiali. L’analisi per fasi eseguita sul modello ha riportato risultati soddisfacenti sia in termini di sforzi che di spostamenti. In particolare, non si sono sviluppate fratture in quanto la resistenza ultima del materiale non è stata mai raggiunta. Per validare il modello, è stato svolto un confronto tra i risultati numerici e i valori ottenuti attraverso il monitoraggio eseguito in cantiere durante lo scarico di una delle colonne. L’errore medio risultante dal confronto è pari al 4% e di conseguenza l’affidabilità del modello si può considerare soddisfacente. Inoltre, è stata verificata la fattibilità dell’intervento tramite un’analisi delle varie fasi di cantiere.
The renovation of Santa Maria di Collemaggio basilica : the intervention on the nave's column
CATELLACCI, LAVINIA
2015/2016
Abstract
On the 6th of April 2009, a devastating earthquake struck L’Aquila causing the partial collapse of the S. Maria di Collemaggio Basilica, one of the most important church in the area in terms of historical and artistic value. Among the serious damages that could be observed, the 12th-century nave’s columns showed serious cracking throughout their height. Therefore, a retrofitting intervention was planned with the two purposes of, first, enhancing the seismic structural behavior of the columns and, second, protecting these valuable elements from future additional damages. In this work, the procedure aimed at unloading the columns in order to allow the restoration intervention is described and analyzed stage by stage. The mentioned procedure had two crucial requirements: first, altering as less as possible the existent state of stress and, second, be easily executed at the construction site. In order to assess the first condition, a 3D FE model of the colonnade and the supported wall has been realized and a construction stage non-linear analyses implemented. The geometry was modeled through the acquisition of the results of a laser scanner survey in order to reflect faithfully the Basilica’s irregularities (lack of verticality of the wall, eccentricities, different dimensions from one column to the other..). Moreover, elastic-brittle constitutive laws were assigned to the model’s materials to reproduce the intrinsic non-linearity of the masonry. The results of the analyses have been attentively analyzed, monitoring the eventual occurrence of cracks or excessive displacements. The stresses, throughout the whole procedure, never exceed the materials’ ultimate strengths. To validate the model, a comparison between the numerical results and the values measured during the intervention has been executed. An acceptable deviation between the values was observed and, therefore, the reliability of the model was assured. Furthermore, the construction site phases of the renovation intervention have been described in detail.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/131511