Performance of HSC columns under severe cyclic loading

Experimental and analytical results of seismic investigation of high strength reinforced concrete columns performance is summarized in this paper. Twelve cantilever columns with different sizes and concrete compressive strengths were tested. The column sizes were 325 mm x 325 mm, 520 mm x 520 mm and 650 mm x 650 mm for the small, medium and large scale specimens, respectively. Concrete compressive strength was 80, 130 and 180 MPa. All specimens were designed in accordance with the Japanese design guidelines. It was noticed that spalling of cover concrete was very brittle for specimens made of 180 MPa followed by a significant decrease in strength independently of the column size. It was also observed that, while concrete compressive strength increases, the drift corresponding to the peak load decreases as well as the ductility of the specimen. Curvature was much important for the small size than for the medium size columns. Specimens with high concrete compressive strength showed a higher equivalent viscous damping at all drift angles. An equation was proposed for predicting the moment-drift envelope curves for the medium and large scale columns knowing that of the small scale columns. Experimental moment-drift and axial strain-drift histories were well predicted using a fiber model developed by the authors.