The Institute for Radioprotection and Nuclear Safety (IRSN) has the task of evaluating the seismic safety of existing building inventory in French nuclear facilities. Some of the existing structures are reinforced concrete frame buildings with masonry or reinforced concrete in-fill walls built during the 1960s, 70s and 80s following different building codes and seismic input data applicable at the time of construction. The studied building is a laboratory that was built in 1962. The building is composed of three different and independent blocks. The structure is a reinforced concrete frame with masonry in-fills and few stiff concrete elements. Moreover, the building contains an independent massive concrete cell. Structurally, the building has a number of irregularities. From the detailing standpoint, well-known deficiencies of low-ductile reinforced concrete structures are evident especially, a lack of transverse reinforcement in the structural joints of the frame. A number of sensitivity studies were conducted using 2D and 3D linear models to evaluate seismic demand. Ambient vibration and regional earthquake records were used to check the soil nature and the existence or not of a possible site effect around the installation as well as to characterize the dynamic behavior of the building. 3D models revealed a strong influence of the slab plates and a torsion in the structure. Also, masonry in-fills can significantly alter the seismic behavior of the building. The building is being subjected to a very large retrofit program submitted for approval to IRSN and the Nuclear Safety Authority. The acceptance criteria used to define deficiencies and to retrofit the building were design criteria.
Nebojsa ORBOVIC, Marc BOUCHON *,
Jacques VENDEL, Thomas GELAIN **