A new sliding pad technique used in the construction of nuclear power stations: the aseismic bearing pads

The construction of a nuclear power station requires an analysis of the seismic conditions, particularly in the region of the proposed site. There are very few regions in the world where the risk of seismic disturbances can be considered negligible. In order to be able to construct power stations presenting adequate security in respect to seismic disturbances, ELECTRICITE DE FRANCE and SPIE BATIGNOLLES have developed a foundation system for a power station on sliding pads permitting standard construction in zones of strong seismic disturbance. Hence standard buildings and machinery can be used which were developed for zones of low seismic disturbance. The research an development for the friction couple used in the sliding pads was carried out by HYDROMECANIQUE ET FROTTEMENT. With this type of pad, the horizontal earthquake accelerations of the structure cause a distorsion of the elastomer block; then, if the horizontal forces exceed a certain value, a sliding action between the friction plates takes place allowing one to limit the accelerations in the structure, and the other, to render them independant of the level of seismic disturbance