SEISMIC STUDY OF HISTORICAL CASTLES AND THE EFFECT OF SOIL STRUCTURE INTERACTION : CASE STUDY OF THE CASTLE OF BASHTOV

Abstract

Historical buildings and monuments of built heritage in Albania suffered great damages during the earthquake of 26 November 2019. Most of them have a structural system of traditional load bearing stone masonry. Field observations and the overview of past interventions of several objects, suggested that the reported damages might have underlying causes, which triggered the main damages during the earthquake. This article focused on the study of damages of stiff masonry walls in castles and their relationship with the earthquake. We took as a case study the Castle of Bashtova, which is one of the few Albanian Castles located in flat terrain and on poor soil conditions. The purpose of this paper is the study of the link between the recorded damages through the history of the structure, the reported damages and the numerical analysis performed for the purpose of structural consolidation interventions. The analysis performed was the linear dynamic analysis with the response spectrum procedure for the calculation of stresses, displacements and their distributions, along with checks of the overall stability of the most critical sections with the Virtual Work Principle. The physical and mechanical properties of the materials were determined in laboratory and in-situ. The study showed that most of the damages reported after the earthquake were due to local effects of soil deposits or soil-structure interaction, local degradation of masonry and not sufficiently connected walls of different phases of construction.