Experimental investigation on the seismic behavior and damage states of reinforced high strength concrete columns

Eight one-third scale concrete columns designed based on the latest seismic provisions for Special Moment Frame systems were experimentally investigated. To do so, the specimens were subjected to lateral cyclic loading and axial loads up to 35% of the axial capacity of columns, other test variables included the concrete strength, spacing, and diameters of transverse reinforcement. Accordingly, damage states were developed accounting for the specimens and attributed to the backbone curve by which the reinforced High-Strength Concrete (HSC) columns capacity and the performance levels were represented. Moreover, the range of drift ratios and damage index limits were proposed and utilized versus the performance levels of reinforced HSC columns used in Special Moment Frame systems. Finally, the correlation between the calculated drift ratio and observed damages such as initial crack, concrete cover spalling, longitudinal bar buckling, and concrete core crushing were studied. The results indicate that reinforced HSC columns have a more reliable performance at Immediate Occupancy and Damage Control levels compare to other levels.