2nd Croatian Conference on Earthquake Engineering 2CroCEE

The structure of the Clock Tower is massive, constructed of stone masonry with a height of about 29 meters and brick masonry in the upper octagonal part. It was damaged during the Skopje Earthquake in 1963. A rehabilitation of the structure was carried out in 1964, but without a seismic strengthening. Recently, field investigations were carried out and a three-dimensional analysis of the structure in its actual state for gravitational and seismic forces was performed. It has been concluded that it is necessary to perform protective interventions to ensure longer-term protection, stability and further existence in the form of repair of existing structural damage, structural consolidation, repair of damaged timber elements and strengthening. To improve the behavior and resistance to dynamic impacts, a technical solution for consolidation and retrofitting has been proposed. The basic concept consists of existing structural damage rehabilitation, structural consolidation with systemic injection, rehabilitation of load-bearing wooden beams and braces and strengthening the whole structure. Due to the specificity of the structure of the Clock Tower in Skopje in terms of its shape, used material, construction system and the type of construction elements, as well as its importance as a cultural and historical heritage, which requires respect of certain conservation principles and rules, the options for rehabilitation and strengthening are strictly limited. It excludes inserting new construction elements that would provide sufficient stability during maximum expected earthquakes. The rehabilitation and strengthening were carried out with innovative composite materials that were experimentally verified, but never applied before. The analysis results show that the retrofitted structure is capable of withstanding the maximum expected seismic loads according to the actual technical regulations.