Diagnosis and preliminary structural analysis of a historic masonry church in Craiova, Romania

The process of identifying optimal strengthening solutions for load-bearing structures damaged by extraordinary actions is a complex undertaking. It is based on the conclusions of analyses carried out by a multidisciplinary team composed of historians, archaeologists, architects, structural engineers, chemists, geophysicists, painting restorers, and others. Furthermore, the article demonstrates that any major intervention on the load bearing structure of a historic monument can disrupt its original equilibrium state and, over time, can even exacerbate structural damage. The use of new materials that have not yet stood the test of time highlights the importance of employing original, local materials that historically ensured, and can continue to ensure, the long-term sustainability of the building. The article presents investigative methods aimed at explaining the complex collapse mechanisms triggered by the accumulation of structural damage caused by repeated seismic events that affect historic churches in the Craiova area, located in southern Romania. The research focusses on the history of reinforcement of the Church of Saints Archangels Michael and Gabriel in Craiova, an emblematic 18th-century masonry structure repeatedly subjected to various actions, including both exceptional events such as earthquakes and long-term actions such as ground settlements and inappropriate human interventions. The study traces the evolution of damage and reinforcement works carried out between 1838 and 1990, analysing the consequences of incompatible and poorly conceived strengthening measures, particularly the insertion of reinforced concrete elements into columns and arches. As part of this investigation, a diagnostic campaign was carried out on site to assess the condition of the church load bearing structure. This campaign employed nondestructive and minimally invasive techniques such as flat-jack tests, thermography, and in situ dynamic analysis. Numerical simulations calibrated with field data revealed critical structural vulnerabilities and confirmed the negative impact of uncoordinated interventions over time. The Romanian seismic safety index (R 3 ), determined for multiple seismic loading directions, indicates that the building currently requires further strengthening due to the adverse effects of previous interventions. The findings reinforce the idea that reversible strengthening strategies − aligned with the principles of the Venice Charter − must be guided by a thorough multidisciplinary assessment of all previous interventions performed on the structure over time.