Seismic performance of ductile and nominally ductile reinforced concrete moment resisting frames. I. Experimental study

This paper is the first of two companion papers on the evaluation of the level of protection offered by ductile and nominally ductile reinforced concrete structures in Canada. In this paper, the seismic behaviour of two half-scale reinforced concrete moment resisting frames is investigated by shake table tests. In the second paper, the experimental results obtained from the shake table tests are compared with the results generated from inelastic time-history dynamic analyses. Each frame had two bays and two storeys with overall dimensions of 5 m in width and 3 m in height. The first structure was designed as a ductile frame according to current Canadian standards; and the second structure incorporated only nominally ductile details. Two levels of intensity were retained for the historical ground motion used in the tests. The first level was representative of the design earthquake considered; the amplitudes were doubled for the second intensity. The ductile structure performed well during both tests. The frame with nominal ductility performed well during the first test, but was on the verge of collapse after the second test. Based on these experimental results, recommendations are presented to harmonize the seismic protection of ductile and nominally ductile reinforced concrete frames in Canada.Key words: moment resisting frames, earthquakes, reinforced concrete, seismic, shake table.