In order to meet the requirements of architecture and structural strength, the design team of the consolidation works had to identify non-invasive means of intervention, which are hidden in the existing structure of the building, without affecting the interior and exterior style of the architectural monument.
The proposed consolidation solution can be divided into three main branches, namely: the interventions made to the exterior of the building, the new reinforced concrete elements that merge with the existing structure, and the tie rods embedded in the walls of the building.
An increased importance is represented by the overall behavior of the building in relation to the land on which it is located. Over the years, due to the terraced profile of the land, the building (especially its southern end) has undergone a tendency to move to the South, namely to the foot of the Metropolitan Hill, it being practically a retaining wall. This tendency determined the obvious sectioning of the building, by the appearance of cracks between the northern body (from the top of the hill), 2 levels high, and the southern one (from the base of the hill), 4 levels high. At the same time, pronounced cracks appeared between the south wing and the rest of the Palace.
To stop the trend of moving the Palace to the South, the design team decided to introduce a pilot front and a support belt designed to resist landslides. This “retaining wall” consists of 0.88m diameter piles that descend to a depth of 12m. At the top, the pilots are supported by a massive beam 1 meter high that laterally supports the southern body of the building. At the same time, the massive beam also represents the foundation of two external consolidation walls. The arrangement of the pilots was provided alternately, in two rows, to increase the capacity of the support system.
The retaining wall is located outside the existing building, which is only adjacent to the structure of the building. The wall surrounds and encloses the southern head on 3 sides, practically blocking its movements both in the North-South and in the East-West direction.
The main method by which the capacity to take over the seismic loads has been increased is represented by the erection of 5 rigid reinforced concrete cores arranged around the meeting room, and by the introduction of new external walls, which are built in the southern body of the Palace. to stiffen. The reinforced concrete walls and cores are born from the foundations of the building, in the basement 2 or 3, and go up to the plate above the second floor, ie the attic plate. Their foundation is made on piloted erasers, individual for each core. The diameter of the mini-pilots is 0.4m, they also have the plug at 12m below ground level.
The location of the newly built cores was chosen so that they do not affect the significant architectural details of the building. As a result, the nuclei were placed in less accessible spaces such as technical spaces, sanitary functions, or vertical circulation. The walls of the cores have a thickness of 60 cm in the basement, of which 50 are embedded in the old masonry walls, and 10 cm protrude from the front of the original walls. On the upper floors, the thickness of the walls decreases, reaching in some cases 40 or 30 cm.
A different approach was needed to shape the walls bordering the corridor around the central hall, part of the P1 core. Like the core, the walls are born from the basement and end in the plate above the 2nd floor. However, they could not be perfectly aligned vertically, being necessary to mask them at higher levels. Basically, the 60cm thick walls are located in basement 2 in front of the old walls, then in basement 1 the newly built wall is embedded in half (30cm) in the old masonry, so that later, on the ground floor and above it, the walls are completely embedded ( 60cm) in masonry. The passage between the walls is made by high capacity transfer beams, section 90x120cm.