A building complex in the center of Athens, which was progressively built in the 1960s and houses the center of the country’s telecommunications organization. It consists of 15 statically independent buildings with basement, ground floor and 2, 5 or 12 floors, of reinforced concrete, with a total area of 53.000 m2.
In the process of redesigning and changing the use of different spaces, architectural enhancements, static and antiseismic strengthening, and new E / M installations are required.
Technology Centers will remain operational and protected against vibration, dust, dirt, water, sparks and other damage during construction.
The strengthening solution provides for the conversion of columns all the way up to “strong columns”, through steel jacketing and concrete infill. Most of the new composite columns have a cross-section with 8 corners to adequately tie up the existing and new concrete they surround. The jacketing increases the strength and deformability of the concrete and makes it practically “unbreakable” under seismic loading.
In height, they are connected by the beams, which are possibly reinforced with a steel jacket. In some cases, where there are insufficient possible positions due to the technology, they are connected by webs, as a composite construction of sheet steel and concrete. Within the web of the new composite walls, the confinement is achieved by cross bars in dense grid. At the same time steel acts as a longitudinal and transverse reinforcement of the web of the composite element, but also as a “lost formwork”. Concrete and tie rods also protect steel sheets from buckling. In technology areas where welding is not allowed, the connections are bolted.
On all floors, the buildings are connected at the joints and are thus converted from 15 to 7 statically independent buildings. This reduces earthquake movements and avoids the risk of pounding, especially between the two 12-story buildings.
In two buildings, which due to the technology cannot be strengthened indoors, strengthening is made on the outside of the facades with shear walls and reinforced concrete frames. The connection to the existing building is made with chemical anchors.
The solution is advantageous in terms of speed, cost, safety, flexibility during the phases, as well as the avoidance of dust, water, vibration and disturbances in the technology.