Layout, Construction and Surveying of Curvilinear Ribs in Late Gothic Vaults. The Case of Priego

Abstract

This paper addresses the study of curvilinear ribs-those with a curved plan- in Gothic vaults, called combados in Spain, from the point of view of their constructive configuration. The objective is to establish relationships between layout, construction and surveying of these members that feature certain formal complexity, through the analysis of the procedures included in 16th century Spanish written sources and the study of the crossing vault of the parish church of Priego in Cuenca (1531–1541). The methodology is based on the analysis of the rib spatial path and the cross-sections that form the actual joints of the curvilinear ribs in the Priego vault, based on a specific photogrammetric and topographic data collection, and its comparison with the methods found in written sources. The work focuses on the geometric control of curvilinear ribs, taking into account both the spatial path and the design of the voussoirs profiles, which in the case of being twisted, allow the rib to follow the inclination of the vault, do not give different height on each flank, and the rib is vertically orientated, without occultations in its plan projection. The hypothesis of a curvilinear rib profile twist depending on that of the main rib from which it springs, which is fulfilled in the procedures by Vandelvira or Rodrigo Gil de Hontañón, does not seem to have been applied exhaustively in Priego, where one type of curvilinear ribs is not twisted and the rest seems to follow a common constant inclination.