THE HISTORICAL PHASES OF THE CHURCH OF SAN LORENZO IN VALENCIA THROUGH THE USE OF THE HBIM METHODOLOGY LAS FASES HISTÓRICAS DE LA IGLESIA DE SAN LORENZO DE VALENCIA A TRAVÉS DE LA UTILIZACIÓN DE LA METODOLOGÍA HBIM

At present, the information about historical buildings is represented as a collection of documents from various sources, elaborated by different professionals. Thus, the inclusion of the HBIM methodology is proposed with the fundamental objectives of streamlining and automating the manipulation of information, facilitating the analysis of complex buildings. This article shows the contributions of the HBIM methodology to the elaboration of the hypothesis of constructive historical phases of the Church of San Lorenzo in Valencia. The working method applied was the proposal of an action model applied to the building, which has its origin in the medieval period and has undergone various transformations throughout its history.


INTRODUCTION: THE CHURCH OF SAN LORENZO
The Church of San Lorenzo in Valencia is part of the first twelve parishes founded after the reconquest of Valencia by Jaume I. Located in the current Plaza de San Lorenzo, its implantation is on an old Arab mosque. The earliest records date to the oldest constrictions in the 13th century.
Since its inception, the original building was modified and expanded on successive occasions. In the 15th century, a side chapel was built, the temple was enlarged and the vaults were built. Later, already in the 18th century, the current tower was built, which has the bell tower in our days, and for almost two hundred years it did not undergo notable modifications until the end of the 19th century when the construction of the Franciscan convent. (Ferrer Orts, 2016) The building is located in the central area defined as " Recinto amurallado de Ciutat Vella y primer ensanche", which has the protection level of Asset of Cultural Interest (Bien de Interés Cultural -BIC) and the category of historical site (DOCV, 1993). In addition, it is part of the catalog of architectural heritage protected as Real estate of local relevance (Bien inmueble de Relevancia Local -BRL), according to the fifth additional provision of Law 4/1998, referring to the Valencian Cultural Heritage. (Fig. 1)

OBJECTIVE AND METHODOLOGY
The Church of San Lorenzo had been studied in 2017 for the subject "Intervención de edificaciones históricas" of the ETSIE of the Polytechnic University of Valencia. The team of teachers formed by Jorge García Valldecabres, Rafael Marín Sánchez and María Concepción López González carried out a high precision graphic survey (Fig. 2) from the laser scanner of the building to form a point cloud. This greatly facilitated the application of the HBIM (Historic Building Information Modeling) methodology in the reconstruction of the historic-constructive phases of the church.
The choice of HBIM was based on the experience of the Church of Santa María in Scaria (Brumana et al., 2013), which sought to reconstruct and study the main transformations and its chronological phases. The process began with the laser scanning of the building in conjunction with photogrammetric surveys to carry out a stratigraphic analysis supported by historical documentation.
HBIM is the extension of the BIM concept and corresponds to a methodology that presents an oriented look for the documentation, conservation, restoration, analysis, and management of historic buildings.
As a starting point for this work, it was considered to exploit the advantages of HBIM to model, manage and visualize the information in a coherent way. The HBIM process, summarily, involves a reverse engineering solution, whereby parametric objects representing architectural elements are mapped based on laser scanner or photogrammetric survey data (Dore and Murphy, 2012). It is a process similar to how one works in building heritage, that is, the application of the science of archeology in architecture and historiographic analysis, as has been developed and implemented in the contributions of Historic England (2017), buildingSMART Spanish Chapter (2018), Castellano-Román and Pinto-Puerto (2019), Santoni et al. (2020). Also relevant, in this sense, are the contributions in archeology by Luis Caballero Zoreda published by the CSIC (Consejo Superior de Investigaciones Científicas).

GENERATION OF THE HBIM MODEL
To generate the model, Autodesk Revit software was used because it had the advantage of linking different types of files from the survey. In principle, the work template was developed and all the project data and the model configurations were incorporated into it.
In the next step, the documents to be used as a reference to start the modeling were imported, being vital at this stage to determine the levels and construction axes of the building. These documents can be 2D and 3D images or geometry, such as CAD files or point clouds.
Once the work template was determined, the geometry of the construction elements of the Church was generated and, for this, it is necessary to define the level of development of the 3D-HBIM model, that is, the degree of accuracy of the geometry and the modeling strategies (LOD). masonry, the arches, and vaults (Fig. 5). In parallel to this process, the dimensions and materials that make up each of the envelopes were configuredthat is, the data from the field survey as well as the historical references in the elements were loaded. In this step, information from survey materials tests could also have been incorporated, such as their physical information. As a result, the families of constructive elements that make up the building were modeled, which can be individual objects or groups. For this case, it was necessary to model the bell tower, the observation balcony, the two façades, the friezes, the oval windows of the facades, among other elements (Fig. 6).
The final product corresponds to a 3D-HBIM geometric model that contains the dimensional and material information of the building, in addition to the parameters assigned to each of the construction elements, and the relationship of the geometric information with the information from image files, plans, tables, texts, etc. (Fig. 7).

RECOGNITION OF HISTORICAL CONSTRUCTION PHASES
From the data collection and the understanding of the information collected mainly composed of historical cartographies, plans, and documents, the hypothesis of the most representative phases preceding the current state of the building is made. This is possible through digital tools, for example with Revit's construction phase determination. In this way, the elements are dated and chronologically arranged.
The tool is adapted to consider the constructive historical phases of the building, thus allowing to visualize and virtually recreate the different states through which the building has passed and provide an easy analysis that allows to understand the causes of current problems. For this case, a total of ten historical landmarks have been distinguished based on the analysis of the building and related documents.
In the development of this research, some applications were experimented in the case of the Church of San Lorenzo as a central information model, resulting in different graphic documents (Fig. 8).

RESULTS
The study and the modeling of the church also facilitated the reconstruction of the building's historical phases, which are extremely useful to understanding some of the current pathologies and to the ability to respond more efficiently to them.
The model shows the original structure of the Church of San Lorenzo, the same one from its origin, which responded to a type known as reconquest, made up of wide, slightly pointed diaphragm arches made of stone or brick, as well as partition walls., two-slope roof, side door, and chapels. After the modifications of the seventeenth century, it went from its medieval to baroque configuration, the arches being demolished to the impost line, preserving buttresses, and building the current slightly lowered partitioned vaults with lunettes.
Finally, the volumetric aggregations that are product of the expansion of the Church and the construction of the Franciscan monastery on the annexed site where an old church cemetery was located are visible. (Fig. 9-10).
The preparation of the 3D-HBIM model, thus, demonstrated one of the various applications it has in the field of information organization to facilitate the understanding of a heritage asset.

CONCLUSIONS
It is observed that the main contributions of the incorporation of HBIM to the architectural heritage correspond to the exploration of its utilities in the study of historical phases, stratigraphies, mapping of pathologies, and the approach of singular elements of the buildings. These are fundamental products for understanding the current state, diagnosing, and proposing conservation and restoration tasks.
The models generated through HBIM thus constitute the starting point for a more complete understanding of historical architecture. They facilitate the understanding of the time and state variables and the possibility of addressing isolated parts or the entire construction.
Among the potentialities presented by HBIM is, in particular, the development of tools that enable to relate of all the geometric information and its data, so these can be managed on specific bases and linked with others. With this, better information management could be obtained for different utilities, such as modifying the model in real-time through, for example, data collection by sensors. El edificio se encuentra dentro del área central definida como "Recinto amurallado de Ciutat Vella y primer ensanche", que posee el nivel de protección de Bien de Interés Cultural (BIC) y la categoría de conjunto histórico (DOCV, 1993). Además, forma parte del catálogo de patrimonio protegido como Bien inmueble de Relevancia Local (BRL), según la disposición adicional quinta de la Ley 4/1998, referente al Patrimonio Cultural Valenciano. (Fig. 1)
Entre las potencialidades que presenta HBIM se encuentra, en modo particular, el desarrollo de herramientas que posibiliten relacionar todas las informaciones geométricas y sus datos para que estos puedan gestionarse en bases específicas y ser enlazados con otros. Con esto se podría obtener una mejor gestión de la información para diferentes utilidades, como la modificación del modelo en tiempo real a través, por ejemplo, de la toma de datos por sensores.