Conservation and strengthening intervention at the ¨C¨ Tower in the Castle of Durrës, after the earthquake in November 2019

Fig.2 Kulla ¨C¨ pas tërmetit të Nëntorit 2019

Built cultural heritage is irreplaceable and very complex; it evolves in time with many elements and systems of heritage. These assets (elements and systems) are becoming very vulnerable due to the unprecedent changes related to rapid development of towns, seismic activity, climate changes etc… Such is the case of the ¨C¨ Tower in the surrounding walls of the ancient city of Durrës.

The tower was built in the late 4th and early 5th century as part of the defensive walls of Durrës and has undergone different changes starting with the collapse of the east wall in the 13th century, to the reconstruction of the Angevin wall and followed by the exterior overall new layer added during Ottoman ruling period (Fig.1).
The 2019 earthquake that hit Durrës’ city caused severe damages on built cultural heritage and ¨C¨ Tower is listed among the damaged ones, with its partial collapse (Fig.2).

In 2019 CHwB-Albania, through the financial support of Ambassadors Fund for Cultural Preservation (AFCP), Swedish International Development Cooperation Agency (SIDA) and the scientific support of World Monuments Fund and Ministry of Culture, began the restoration process that follows three phases of activities:

  • Phase 1- Emergency stabilization
  • Phase 2 – Design of conservation measures
  • Phase 3 – Implementation of conservation measures

Currently, phase 1 (Fig.3,4) and 2 are finalized and phase 3, the implementation of conservation measures, is ongoing.

In order to design the conservation proposal, a series of studies were conducted as follows: i) geological (fig.5); ii) geo radar documentation; iii) building materials (Fig.6); iv) archaeological survey (Fig.7) and v) seismic analysis through Kinematics (Fig.8) and numerical calculations applied to define the capacity of the structure. Then, the FEM analysis of relative movement was conducted (Fig.9), due to differential settlements, to compare the existing cracks in the structure with the ones generated by the numerical model (Fig.10).

The result gave a clear picture of the collapse causes; the cavity in the foundation led to the development of vertical cracks, rotation of detached block, and consequently out-of-plumb deformation, while the earthquake caused the overturning of the wall affected by rocking phenomena (Video. 1).

Finally, conservation and strengthening proposals are designed based on the interpretation of the results streaming from the analysis. These proposals consist in the consolidation and repair of the foundation wall through traditional techniques, rebuilding of the collapsed wall with the fallen wall blocks (Fig.11), installation of stainless-steel ties to improve the global behaviour of the structure and cleaning and repairing of the wall to restore ¨C¨ Tower (Fig.12).

To learn more about the conservation process visit us in Durrës at the temporary structure ¨Qoshku¨ located in the construction site.

Video.1 Collapse mechanism through Discrete Element Method analysis.