Modelado de información y alteraciones geométricas para respaldar el análisis preciso de activos patrimoniales

Abstract

The virtual documentation of the architectural, archaeological and cultural heritage is a field of knowledge with a growing presence in the scientific literature. Geometric data acquisition techniques such as three-dimensional scanning are widely used in research and restoration projects in heritage, since they allow to capture the geometric characteristics of assets. In the latest decades, these techniques have been implemented in Building Information Modeling platforms to create information models of historical buildings and sites (HBIM). However, the excessive simplification in virtual modelling entails failing to reproduce the real conservation status of these assets, which in turn makes it impossible to obtain accurate results in the analyses that can be performed on the assets. Therefore, this doctoral thesis focuses on developing a methodology to generate information models of the architectural, archaeological and cultural heritage in their current conservation status (as-built models) from 3D digitisation, modelling their geometrical alterations, in order to support accurate analysis of these assets to contribute to their conservation. For this purpose, a critical analysis of 3D capture technologies (terrestrial laser scanning and optical scanning) and existing methodologies and their applications in the heritage context is carried out. This involves validating the point cloud meshing process for the constitution of as-built models. Next, a three-step semi-automatic procedure (point cloud — 3D mesh — 3D solid object) is proposed for the virtual reconstitution in HBIM of historical buildings and other heritage assets in their current conservation status. With a view to test and validate the proposed methodology, this thesis addresses the generation of information models of two case studies (the Pavilion of Carlos V in the Real Alcázar of Seville and the columns of the Basilica in the Archaeological Ensemble of Baelo Claudia in Tarifa) for their accurate structural geometrical and numerical analyses. On the one hand, the geometrical analysis consists of studying the displacements, the distortions and the surface deformations of the columns, as well as the distribution of the geometrical alterations. On the other hand, the numerical analysis focuses on the structural behaviour assessment of the most unfavorable column in terms of structural geometrical alterations through the Finite Element Method. These analyses are carried out in different modelling approaches for the case studies based on their geometrical alterations: (1) as-built, (2) simplified and (3) ideal modelling without deformations. The results of both the geometrical analysis and the structural analysis reveal the great impact of the as-built information and geometrical alterations modelling of heritage on the accuracy of the studies on its conservation status. Thus, these as-built models allow for identifying and measuring the elements or areas which show structural and surface weaknesses through the study of the extent of their geometrical alterations and deformations. In this sense, the geometrical analysis of the most structurally unfavorable column in the Basilica, based on the proposed as-built modelling methodology, allows to obtain displacements and distortions of 132% and 235%, respectively, against the rest of the columns and its ideal geometry. In relation to its structural simulation considering the as-built model, a 50% increase in the maximum shear stress is achieved with respect to the simplified model. Therefore, the main contribution of this thesis lies in proposing a methodology for the generation of HBIM information models, based on 3D scanning data, which are useful for diverse analyses and simulations to accurately determine the physical status of the assets for their preservation over time. Notwithstanding, this does not limit the application of the proposed methodology for heritage to other disciplines that can benefit from the as-built modelling of elements, constructions or spaces for subsequent analysis.