Study of the behaviour of a reinforced concrete post under aleatory excitation

The reactor building of a nuclear power plant must ensure its protection and tightness functions in the most unfavorable conditions of operation, like during an earthquake. The method currently used for the seismic calculation of buildings consists in the determination of the maximum probable response for each of the Eigen-modes of the structure. The aim of this study is to develop a non-linear calculation model for the estimation of the response of reinforced concrete structures. The structure under study is a beam embedded in its base and having a 2 tons load on its top. The structure is excited by a seismic or pulsed signal. In a first step, the global behavioural model of reinforced concrete is determined using the concrete and steel armatures behaviour laws. Then, a computer code is developed for the calculation of the seismic excitation of the beam. The beam is assimilated to a non-linear oscillator. A damaging parameter has been introduced in the model to take into account the damping observed experimentally. Finally, the excitation signal is analyzed in order to determine the parameter responsible for the significant increase of the structure response. (J.S.)