EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF LARGE SCALE REINFORCED CONCRETE COLUMNS WITH STRONG CONFINEMENT

To investigate the seismic performance of reinforced concrete columns with strong confinement, quasi-static tests on six full-scale reinforced concrete columns with stirrup characteristic values in the range of 0.34~0.44 and with section dimension 450mm#x000d7;450mm were conducted. The test results indicated that the failure modes of specimens were compression-bending; the longitudinal bars buckled in compression and even broke; several stirrups fractured. Within a height of one time of column depth above the column bottom the concrete cover spalled seriously and the confined concrete partially crushed. The lateral force-displacement hysteretic loops were plump, the ultimate drift ratios ranged from 1/39 to 1/33 and the ductility coefficients were greater than 3. Changing the stirrup types or changing the space of stirrup legs had little effects on the load-carrying capacity and ultimate deformation capacity of specimens. Increasing the number of lateral loading cycle from 3 to 5 had little effects on the load-carrying capacity and peak deformation of specimens, but led to about 15% decrease of the deformation capacity.