Application Of A Simplified Model To The Out-Of-Plane Behaviour Of Masonry Structures With Frictional Resistances: The Ancient Citadel Of Al-Baleed

Starting from early 2007 a team of structural engineers of the University of Pisa has been involved in the consolidation of the Fortress of Al Baleed in Salalah (Sultanate of Oman), erected about 1100 A.D., within an UNESCO archaeological excavation process managed by the Institute of Archaeology of the Missouri University. A simplified model to evaluate the behaviour of the out-of-plane loaded masonry walls both during excavation and after consolidation has been performed assuming that the failure mechanism occurs through the rotation of macro blocks about cylindrical hinges. The solutions in terms of either maximum collapse height of excavation or maximum free height of restored walls are found by means of the kinematical approach of limit-state analysis, also accounting for the interactions of frictional shear forces and torsion moments arising along the crack lines. A numerical application to six different walls has been carried out, together with a parametric analysis considering two different climate conditions typical of this geographical area (rainy season, named Kareef, and dry season). Set of diagrams containing the results are presented and discussed to remark the influence of the main physical and geometrical parameters on the collapse conditions