Papers by Ramon Gonzalez Drigo
Infrastructures
Several methodologies for assessing seismic risk extract information from the statistical relatio... more Several methodologies for assessing seismic risk extract information from the statistical relationship between the intensity of ground motions and the structural response. The first group is represented by intensity measures (IMs) whilst the latter by engineering demand parameters (EDPs). The higher the correlation between them, the lesser the uncertainty in estimating seismic damage in structures. In general, IMs are composed by either a single (scalar-based IMs) or a group of features of both the ground motion and the structure (vector-valued IMs); the latter category provides higher efficiency to explain EDPs when compared to the first one. This paper explores how to find new vector-valued IMs, which are highly correlated with EDPs, by means of multi-regression analysis. To do so, probabilistic nonlinear dynamic analyses have been performed by considering a seven-story reinforced concrete building as a testbed. At a first stage, 30 scalar-based IMs have been correlated with 4 EDP...
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Este estudio recoge los principales resultados del trabajo sobre modelización de la anelasticidad... more Este estudio recoge los principales resultados del trabajo sobre modelización de la anelasticidad en la Península Ibérica a partir de ondas de Coda correspondientes a una selección de 935 registros sísmicos digitales registrados en 27 estaciones equipadas con instrumental de corto periodo y pertenecientes al Instituto Geográfico Nacional (IGN). Tras la selección, se ha aplicado sistemáticamente la corrección por respuesta instrumental sobre todas las señales a analizar. Los sismos disponibles para este estudio ocurrieron en el intervalo 1997-1999 y se sitúan en las siguientes tres áreas en las que se concentra la sismicidad natural de la Península Ibérica: El Noroeste Peninsular (Galicia); El Noreste Peninsular (Cataluña, Aragón, Navarra y, parcialmente, el sur de Francia); El Sur Peninsular (sur de Valencia, Murcia, Andalucía y, parcialmente, el sureste de Portugal).Mediante métodos basados en la dispersión simple se ha calculado el factor Q de coda y su dependencia frecuencial en ...
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Heritage
Structural damage detection is an important issue in conservation. In this research, principal co... more Structural damage detection is an important issue in conservation. In this research, principal component analysis (PCA) has been applied to the temporal variation of modal frequencies obtained from a dynamic test of a scaled steel structure subjected to different damages and different temperatures. PCA has been applied in order to reduce, as much as possible, the number of variables involved in the problem of structural damage detection. The aim of the PCA study is to determine the minimum number of principal components necessary to explain all the modal frequency variation. Three estimators have been studied: T2 (the square of the vector norm of the projection in the principal component plan), Q (the square of the norm of the residual vector), and the variance explained. In the study, the results related to the undamaged structure needed one principal component to explain the modal frequency variation. However, the high damage configurations need five principal components to explai...
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2018 17th International Conference on Ground Penetrating Radar (GPR), 2018
Corrosion is a common pathology in modernist (art nouveau) structures due to the employment of me... more Corrosion is a common pathology in modernist (art nouveau) structures due to the employment of metallic reinforcement in masonry or mortar elements. This pathology can be the cause of important damage. Therefore, detection of corrosion is important in the cultural heritage assessment. Moreover, these cultural heritage structures are usually fragile and must be assessed with the minimum intervention, being non-destructive test (NDT) usually applied to these studies. However, detection of corrosion using NDT is difficult and only specific zones can be analyzed. Therefore, in most cases, results are incomplete. In this study, GPR was applied to obtain information to evaluate of the corrosion damage. The application of this methodology provides results from vast areas with a fast survey acquisition. GPR, as an NDT technique, covers large areas of study while other methods are constrained to a small areas or specific points. In this paper it is presented the study of the mosaic roofs in the Park Giiell, in Barcelona. This park is one of the most key Modernista (Art Noveau) complexes in this city. It is characterized by structures with roofs and banks with tessellation. Some of these structures are most likely supported by metallic elements, and seepage cause significant damage observed over the tessellation. The objective of the study was to define the possible existence of those metallic targets, determining their location. In the case of existence of metallic elements it determines which are the zones more affected by corrosion. Results demonstrate the existence of metallic supports in many parts, as well as some defined areas that could be damaged.
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Remote Sensing, 2019
In this study the main results of a detailed analysis of an actual building, which was severely d... more In this study the main results of a detailed analysis of an actual building, which was severely damaged during the Mw 5.1, May 11th 2011, Lorca earthquake (Murcia, Spain) are presented. The dynamic behavior of the building was analyzed by means of empirical and numerical approaches. The displacement response of the building submitted to ambient noise was recorded by using a Real Aperture Radar (RAR). This approach provides a secure remote sensing procedure that does not require entering the building. Based on the blueprints and other available graphical information about the building, a numeric 3D model was also set up, allowing obtaining capacity spectra and fragility curves in the two main resistant directions of the building. The main purpose of this study was to check out the feasibility of the RAR-based method to detect the safety state of a damaged building after an earthquake, without the need of entering unsafe structures. A good consistency of the numerical and experimental...
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Journal of Physics: Conference Series, 2018
This paper reports the use of an interferometric radar to support the detection of the main vibra... more This paper reports the use of an interferometric radar to support the detection of the main vibrating frequencies of a building damaged after the Mw 5.1, May 11th 2011, Lorca earthquake (Southeast Spain). The surveyed building, a reinforced concrete structure, was located in the San Fernando neighbourhood of the city of Lorca, where the earthquake caused severe damages. The radar survey was carried out some months after the earthquake. To assess the building capacity and fragility, a pushover analysis has been carried out. The building has been modelled by using the SAP2000 software. The goal of the study is to detect changes of the main natural frequencies of a specific building after the earthquake and, through a comparison of the building frequencies before and after the earthquake, to estimate the effect of the earthquake on the monitored building.
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2015 8th International Workshop on Advanced Ground Penetrating Radar (IWAGPR), 2015
This paper describes the application of ground penetrating radar (GPR) in the study of the shallo... more This paper describes the application of ground penetrating radar (GPR) in the study of the shallow geology of urban environments, applying the survey in Barcelona city. The objective is to determine the existence of clusters of granular materials that could be related to paleochannles or subterranean streams. The method proposed for this study is to evaluate the signal to noise ratio (SNR) in radar data, caused by the backscattered energy as consequence of small targets. Laboratory tests and previous works indicate that variations of the SNR allow the detection of these sedimentary structures. The results will be used in the design of a detailed grid of points where soil vibrations must be measured. The combined methodologies allowed the construction of precise seismic microzonation maps of the city.
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2015 8th International Workshop on Advanced Ground Penetrating Radar (IWAGPR), 2015
The Santa Creu and Sant Pau hospital is a monumental ensemble built in Barcelona between 1901 and... more The Santa Creu and Sant Pau hospital is a monumental ensemble built in Barcelona between 1901 and 1930 on the site where six small medieval hospitals were founded in 1401. It is a complex of buildings which represent the art nouveau architecture in Barcelona. It was declared World Heritage site by the UNESCO in 1997. In the previous eight decades of clinical activity, modernist buildings have experienced numerous architectural modifications that have affected both their structures and ornamental elements. The deterioration of the buildings became apparent in 2004. In this situation, in 2006 a master plan to assess the state of the hospital evidenced the critical state of many of its pavilions, and therefore a complete rehabilitation project for the entire ensemble was approved. The assessment of some specific structural elements, that is spandrels and columns, located in the Pharmacy pavilion and in the hospital church, has been performed and evidenced the presence of metallic elements, sub-structures and, in some cases, corroded iron elements, embedded in the masonry structure. A detailed description of these embedded elements and some damaged areas inside the columns was performed through a non-destructive prospection with ground penetrating radar. A 1.6 GHz nominal center frequency antenna was used in this assessment.
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IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2016
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2015 8th International Workshop on Advanced Ground Penetrating Radar (IWAGPR), 2015
The Museum of Contemporary Art of Valdivia is located in an area characterized by high seismic vu... more The Museum of Contemporary Art of Valdivia is located in an area characterized by high seismic vulnerability. The building and the surrounding area were truly affected by the 1960 earthquake. The edification, built in 1855, is next to the River Valdivia, which undergoes high fluctuation in the salinity. Moreover, the structure suffers of lack of maintenance and the visual inspection denotes different types of damage in different zones. Previous to the rehabilitation, the structure was evaluated with Ground penetrating radar (GPR). The two main objectives of the survey were determining structural arrangement of walls, floor and roof, and to detect possible damage. Visual inspection indicated that some of pathologies were sunken layers, cracks and zones affected by high water content. Many of the damage could be caused by the seismic hazards in the area, and the humid climate. The GPR assessment was carried out with a shielded 800 MHz centre frequency antenna, covering all the different zones of the building.
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Journal of Cultural Heritage, 2008
... Vega Pérez-Gracia a , Corresponding Author Contact Information , E-mail The Corresponding Aut... more ... Vega Pérez-Gracia a , Corresponding Author Contact Information , E-mail The Corresponding Author , Francisco García b , E-mail The Corresponding Author , Lluis G. Pujades c , E-mail The Corresponding Author , Ramón González Drigo a , E ... [1] H. Lorenzo Cimadevila, MC ...
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Detection of corrosion is important in cultural heritage assessment. Many structures contain meta... more Detection of corrosion is important in cultural heritage assessment. Many structures contain metallic targets embedded in masonry or mortar, and corrosion cab cause important damage. However, detection using nondestructive methods is difficult and highly localized, providing in most cases incomplete results. In order to obtain a more extended analysis, GPR was applied and evaluated to detect damage as consequence of corrosion. This technique is a non-destructive method that covers a large area of study while other methods are constrained to a small areas or specific points. Therefore, some controlled laboratory tests were designed to determine possible differences in radargrams obtained in the case of corroded and non-corroded targets. These analysis allowed to observe that the corrosion seems to increase the attenuation of the radar signal, being difficult to detect targets near the damaged bars.
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Papers by Ramon Gonzalez Drigo