Multidisciplinary Approach for the Analysis of Structural Heritage at Risk: The Case Study of Stylite Tower at Umm ar-Rasas (Jordan)

The results of multidisciplinary research carried out on the Byzantine Stylite Tower in Umm ar-Rasas archaeological site (Jordan) are presented in this paper. The study is grounded on the precarious structural conditions of the tower, assessed by UNESCO since 2008. In 2019, during an archaeological campaign, an aerial photogrammetry survey was performed, allowing for the creation of a detailed 3D model of the tower. This new dataset was compared with existing Geomatics surveys (collected in 2016 with Terrestrial Laser Scanner) within a common reference system, showing that the tower leans dangerously in the northwest direction. With the combined use of the photogrammetric and historical investigations data, the structural vulnerability of the building was analysed in-depth. Starting from the new point cloud dataset, a multi-step geometrical modelling strategy was performed to define the structural model based on the actual geometry of the tower. 3D documentation with aerial photogrammetry made it possible, for the first time, to account for the actual 3D geometry of the upper cell in the structural analysis of the tower. Several possible out-of-plane mechanisms involving the upper cell walls and portions of the tower façades were analysed via kinematic analysis using the floor response spectra. The study revealed a new critical and risky scenario, which suggests a prompt intervention for the safe conservation of the tower.