SEISMIC PERFORMANCE OF REINFORCED CONCRETE EXTERIOR BEAM-COLUMN JOINT WITH COLUMN-TO-BEAM STRENGTH RATIO EQUAL OR NEAR UNITY

Tests on reinforced concrete exterior beam-column joint sub-assemblages with low column-to-beam strength ratio in the range commonly constructed in practice are reported. Story shear capacity of some specimens were 30% lower of the story shear predicted by the flexural strength of the beam or the column at the maximum, although the joints have enough margins for nominal joint shear capacity by 10% to 50%. The decrease of story shear is larger in the case of the column-to-beam strength ratio is equal or near to unit. Column-to-beam strength ratio required to secure lateral strength predicted by the flexural strength of sections is small in the case of that the amount of transverse reinforcement in the joint is large, the column depth is large relatively to the beam depth or bent bar anchorage is used instead of mechanical anchor with headed bars.