In this paper the experimental tests on an earthquake-damaged four-storey concrete building located in L'Aquila (Italy) are reported. The building, which is irregular both in plan and in elevation, was classified inhabitable after the inspections subsequent the earthquake of April 6th 2009. The structure is composed by reinforced concrete frames, with horizontal concrete slabs, lightened by means of clay air-bricks. The walls, also made of clay bricks, do not collaborate in the structural behavior. The building suffered damages during the earthquake, especially at the first level.