Experimental Evaluation of Crossties in Large Reinforced Concrete Columns under Pure Compression

The effectiveness of crossties in six sets of large-scale reinforced concrete short columns under monotonic axial compression is evaluated experimentally. The primary variables were type of crosstie engagement, type of crosstie, and crosstie placement offset. It was observed that minor placement offset up to 20 mm between hooks of crossties and longitudinal steel bars does not bring unfavorable consequences in confinement. The crosstie hook engagement of both hoop and longitudinal steel bar is better than that engagement of the longitudinal steel bar alone, but it is difficult in installation. Crossties composed of two straight end-180-deg hook steel bars give the best performance among the types of crosstie and it is convenient to facilitate the fabrication of reinforcing cages. However, the effectiveness under cyclic loading needs further study.