Existing 1980s residential building, made of reinforced concrete, in Paleo Psychiko, Athens, designed by the architect Jason Rizos.

It consists of a basement, a “pilotis-form” ground floor, 3 more floors and a roof.

The 36 columns of the “pilotis”- level floor suffered severe damages due to ascending moisture from the ground, such us oxidation of the reinforcement bars and rupture – spalling – of the reinforcements’ concrete covers.

Concrete samples were taken and tests were done and the reduced concrete strength of these columns was measured and verified.

Consequently, there was an urgent need to restore and strengthen the of “pilotis” columns, to eliminate the risk of their failure under static and seismic loads.

For this purpose, cubus designed steel-sheet “jackets” all around the columns and fully attached to them.

Each “jacket” was connected with its column, through additional transverse steel rods on the elongated sides, at the full height the columns, so that they act as confined, composite columns, having adequate strength under compression and shear.

The dimensions of the columns’ cross-sections increased slightly, about 3cm in length as well as in width.

Their exterior texture and appearance remained the same as that of the “fare-faced” concrete they had before the interventions, through the application of special paint on the “jackets”.

In the case of columns who had inaccessible sides, the “jackets” were replaced by composite structures from reinforced concrete and steel profiles.

Interventions’ works were limited to the “pilotis”-level, they were completed within two months, without disturbing the residents, with the maximum economy and absolute safety of everybody.

The architecture and aesthetics of the building were not affected at all.