Comportement sismique d'une ossature ductile en beton arme (R = 4)

The amplitude of the design seismic lateral loads and the complexity of seismic reinforcement detailling to be incorporated in a reinforced concrete moment resisting framed structure in Canada depend on its available ductility capacity. In "ductile" moment resisting frames, the design lateral loads are reduced significantly, but the high ductility of the structure is ensure by strict detailling requirements to avoid premature brittle failure modes. This approach, according to the seismic design philosophy of the National Building Code of Canada, should offer an adequate level of seismic protection in the event of the design earthquake at the construction site. Considering the large uncertainties associated with the design earthquake, it is questionable if this level of protection is maintained under more severe ground motion intensities.;The objective of this investigation is to evaluate the level of protection offered by ductile reinforced concrete moment resisting framed structures. Shake table tests of a half scale moment resisting frame were performed on the high performance earthquake simulator at Ecole Polytechnique. The frame had two bays and two storeys with overall dimensions of 5 m in width and 3 m in height. The structure was designed as a ductile moment resisting frame according to the current Canadian standards. Two levels of intensity were retained for the historical ground motions used in the shake table tests. The first level was representative of the design earthquake at the site, while the amplitude of the ground motion was doubled in the second intensity.;The frame performed according to the code design philosophy for both intensity levels. Plastic hinges occured in the beams and at the base of the first floor columns. The experimental results indicate that ductile reinforced concrete moment resisting frames, designed according to Canadian code requirements, are adequate to resist high intensity ground motions.