Ground floor small building, as an addition to an existing villa, in a very seismic prone area, such as Loutraki in the prefecture of Korinthia. The aim was to transform the existing building into a cultural center and its “addition” into a library. The new building had to be completely modern from an architectural and “building systems” point of view, with glass shell for light and unobstructed visibility and blinds for shading, but also bioclimatic, with a planted roof. The architectural design required the absence of vertical concrete structural elements inside the building, so that the interior is completely transparent. As structural engineers we have proposed the construction of six composite structural steel columns with a composite roof. For stiffness, each column consists of four hollow sections (tubes) filled with concrete, connected to each other by steel blades, which in a very large earthquake can also suffer a slight damage, easily repairable. It is a system of absorption of seismic energy, of particular architectural aesthetics. The result was completely satisfactory; the building is a meeting and educational center for young people.