A Structural Analysis of the Agios Petros Tower for its Historic Preservation

Abstract

“The conservation and restoration of monuments must have recourse to all the sciences and techniques which can contribute to the study and safeguarding of the architectural heritage.” - Article 3 of The Venice Charter [36] This thesis aims to evaluate the structural integrity of the Agios Petros Tower in its current state and use this assessment to understand the plans that must be developed for its preservation. The Agios Petros Tower on the island of Andros in Greece is an example of a historic structure. Built out of dry-stack stone masonry during the Hellenistic Age and used for an assortment of purposes throughout its lifetime, the tower represents an immense structural accomplishment, given that it continues to stand more than two millennia later. Despite its resilience, at present, the tower is in a precarious state as there are missing stones and entire sections, as well as masonry in extremely poor condition, which is concerning for its future preservation. As described in Article 3 of The Venice Charter, it is the job of engineers to utilize all possible resources to maintain architectural heritage. Thus, it is necessary to obtain a comprehensive understanding of the structure by both contextualizing its historical background as well as assessing its structural behavior. A thorough visual investigation was conducted, including a Masonry Quality Index test to gauge the overall condition and to gain an understanding of the mechanical properties of the material. Its structural performance was further analyzed through Finite Element Modeling (FEM), utilizing a macro-modelling approach. Subject to different loading conditions including various combinations of gravity, wind, and seismic actions, the results of the FEM simulations closely matched the analytical results and showed tensile stress in the tower. This is highly concerning for its future conservation as the structure is entirely made of stone masonry, a material with an extremely low tensile capacity. The loading conditions involving seismic actions exhibited behavior most detrimental to the state of the tower, however, even under solely gravity loads, the tension experienced in the tower far exceeds the tensile capacity of dry stack masonry. Future work could involve taking a micro-model discrete element modeling approach in order to better understand the interactions of the individual masonry units. However, this thesis numerically and analytically examines the overall behavior of the structure, while considering a qualitative understanding of the material quality and demonstrates the necessity to preserve the tower. The final portion of this thesis therefore explores various possibilities for the tower’s future preservation to ensure that it can be appreciated for future generations.