Evaluation of large deformations on Romanesque masonry pillars: The case of Santa María de Arties (XII-XIII) at Valle de Arán, Spain

Abstract

There is a set of Romanesque churches at Valle de Aran that were built between the eleventh and thirteenth centuries; these churches have suffered large deformations and geometrical displacements. These deformations have provoked, in some cases, convex shapes to appear, in relation to the generatrix of the vaults, which have the inverted shape of an arch. Geometrical assessment of the least rigid elements, the pillars, makes it possible to analyse the displacements, which have been the cause of funicular shapes on some vaults. It is possible to deduce the regression plane of the displacements of the pillars of the central nave and to define the deformation vectors over it. Thus, these data reveal the directions of the deformations of vaults and pillars to be determined. The deformations of the pillars are not perpendicular to the directrix of the central vault, so the methodology and results can be very useful to understand the nature of the displacements and to maintain these masonry structures.Key words: Romanesque, masonry, barrel vault, pillar, great deformations, Valle de Arán. ResumenEn el Valle de Arán existe un conjunto de iglesias románicas que fueron construidas entre los siglos XI y XIII; estas iglesias han sufrido grandes deformaciones y desplazamientos geométricos. Estas deformaciones han provocado que, en algunos casos, que aparezcan formas convexas, en relación con la generatriz de las bóvedas, que tienen la forma invertida de un arco. La evaluación geométrica de los elementos menos rígidos, los pilares, permite analizar los desplazamientos, que han sido la causa de las formas funiculares en algunas bóvedas. Es posible deducir el plano de regresión de los desplazamientos de los pilares de la nave central y definir los vectores de deformación sobre ella. Así, esta información permite determinar la dirección de las deformaciones de bóvedas y pilares. Las deformaciones de los pilares no son perpendiculares a la directriz de la bóveda central, por lo que la metodología y los resultados pueden ser muy útiles para comprender la naturaleza de los desplazamientos y para mantener estas estructuras de mampostería.

Methodologic Evolution Assessment of Large Deformations on Romanesque Masonry in Val d‘Aran (XII-XIII centuries), Spain

“…Figure 2. Methodology of the geometrical assessment of Santa Maria Arties pillars' [35] The assessment of the deformations of the elements under its own weight, especially the central and lateral vaults, makes it possible to deduce that external actions, such as snow or seism. These external actions, together with the loss of lime mortar, inasmuch as humidity or vibrations, cause the primitive function fi(x,y,z) of the vaults.…”

“…Figure 1. Santa Maria Arties (XII-XIII) [35] In order to analyse the deformations of the church of Santa Maria Arties (XII-XIII), we used the point cloud extract from the scanner Leica ScanStation P20, with a bandwidth of 808/658, class 1. The scanning ratio is 1,000,000 points, and the noise at 100 is 9.0 mm for black surfaces, 4.30 mm for grey surfaces, and 1.5 mm for white surfaces.…”

“…Thus, pillars have following rows: (P1=26), (P2=26), (P3=27), (P4= 25), (P5= 23) and (P6= 23). Rows are numbered from bottom to top [35]. The identification of pillars' joints was made by means of a manual measurement system, for the reason that the graphical capacity of the software Cyclone, and the program 3DResheaper, does not allow to specify pillar's joints because it constructs it three-dimensionally (Figure 3).…”

Terrestrial Laser Scanner for the Formal Assessment of a Roman-Medieval Structure—The Cloister of the Cathedral of Tarragona (Spain)

“…Many studies have developed simple (and not so simple) to address deformation of ancient structures from point clouds. Examples of it are the studies performed in the church of Santa Maria of Portonovo [15], the Cantalovo church [16], the Palazzo d'Accursio [17] (the three of them in Italy); the church of Santa Maria de Arties [18] or the Cathedral of Tortosa [19] (both in Spain), among many others. TLS surveys and displacement assessments can be also combined with other procedures of structural analysis [20], [21].…”