Historic masonry buildings may present different wall structures as a function of their typology and their use. Thus, according to the role of the building, a different masonry typology, with different constructive technique, could be observed in each historical construction. The worst structural defect of a masonry wall, mainly in seismic area, can be the lack of monolithic behaviour and this can happen in case of poor quality and morphology, for instance when the wall is made by multiple leaves even well ordered but not mutually connected. These problems are observed mainly in stone masonry, which is the most variable one. Therefore it’s extremely important, when approaching a historic building, the analysis of its masonry structure, not only considering its single components but also evaluating the whole masonry and its quality. There are different levels to approach the matter, starting from a description based on a visual inspection, that can be carried out with the help of a template, till the parameters definition achieved by in situ investigation tests. Only the last Italian seismic code (NTC 14.01.2008 and annexes) started to stress the importance of the masonry quality analysis, classifying it among some typologies reported in one table and attributing different mechanical parameters useful for the structural evaluation. Serious mistakes can be made in the structural evaluation of a historic stone masonry if the definition of the masonry typology is incorrect. In several cases a masonry texture can appear externally good and regular while the cross section is poor with non connected multiple leaves, or, on the contrary, the masonry texture appears irregular from the prospect with small irregular stones of different dimensions while the cross section shows a well interlocked masonry with long stones used as connection among the leaves. Some examples will be presented in this paper, such as the case of the XIX cent. ex-hospital of Savona, a three storey masonry building, where diagnostic tests showed a reliable mechanical behaviour despite the appearance of the masonry texture. On the contrary, a poor irregular stonework may be poor also in its cross-section, as a large number of historic masonry buildings in the Abruzzo region (area hit by a large number of past earthquakes, till the last in 09.06.2009). Even if the traditional diagnostic tests results classified it as a real poor masonry, the tradition accepts the same masonry typology also for important constructions over the centuries. Several parameters may be thus important to be determined in order to evaluate properly a masonry. The results of the experimental investigation (with a comparison between NDT and MDT tests) and a methodology for the analysis of the masonry quality, according to the standard suggestions for the knowledge levels, reporting all the pros and cons of all methods, are here presented.

Guidelines for the masonry quality evaluation in built heritage

CARDANI, GIULIANA;BINDA, LUIGIA
2013-01-01

Abstract

Historic masonry buildings may present different wall structures as a function of their typology and their use. Thus, according to the role of the building, a different masonry typology, with different constructive technique, could be observed in each historical construction. The worst structural defect of a masonry wall, mainly in seismic area, can be the lack of monolithic behaviour and this can happen in case of poor quality and morphology, for instance when the wall is made by multiple leaves even well ordered but not mutually connected. These problems are observed mainly in stone masonry, which is the most variable one. Therefore it’s extremely important, when approaching a historic building, the analysis of its masonry structure, not only considering its single components but also evaluating the whole masonry and its quality. There are different levels to approach the matter, starting from a description based on a visual inspection, that can be carried out with the help of a template, till the parameters definition achieved by in situ investigation tests. Only the last Italian seismic code (NTC 14.01.2008 and annexes) started to stress the importance of the masonry quality analysis, classifying it among some typologies reported in one table and attributing different mechanical parameters useful for the structural evaluation. Serious mistakes can be made in the structural evaluation of a historic stone masonry if the definition of the masonry typology is incorrect. In several cases a masonry texture can appear externally good and regular while the cross section is poor with non connected multiple leaves, or, on the contrary, the masonry texture appears irregular from the prospect with small irregular stones of different dimensions while the cross section shows a well interlocked masonry with long stones used as connection among the leaves. Some examples will be presented in this paper, such as the case of the XIX cent. ex-hospital of Savona, a three storey masonry building, where diagnostic tests showed a reliable mechanical behaviour despite the appearance of the masonry texture. On the contrary, a poor irregular stonework may be poor also in its cross-section, as a large number of historic masonry buildings in the Abruzzo region (area hit by a large number of past earthquakes, till the last in 09.06.2009). Even if the traditional diagnostic tests results classified it as a real poor masonry, the tradition accepts the same masonry typology also for important constructions over the centuries. Several parameters may be thus important to be determined in order to evaluate properly a masonry. The results of the experimental investigation (with a comparison between NDT and MDT tests) and a methodology for the analysis of the masonry quality, according to the standard suggestions for the knowledge levels, reporting all the pros and cons of all methods, are here presented.
2013
Online Proceedings of Conference Built Heritage 2013 - Monitoring Conservation and Management
978-88-908961-0-1
Stone masonry walls; masonry quality; crack pattern; sonic test; flat jack test.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/871955
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