Seismic investigation of reinforced concrete columns with different transverse reinforcements

In this study, cyclic lateral load tests of eight large diameter circular reinforced concrete column specimens are conducted to investigate the feasibility and effectiveness of both single-cross and double-cross lap-spliced crossties on confining reinforced concrete columns. The tests involve four series of specimens-R, S33, S17, and D33 with the same total confinement force of the circular ties and crossties. The confinement forces of the single-cross and double-cross lap-spliced crossties are respectively calculated by multiplying the cross-sectional area of one and two crossties with the nominal yield strength. Firstly, the results reveal a small, nonsignificant correlation between seismic performance and lateral force direction. Therefore, assigning a direction to single-cross or double-cross lap-spliced crossties is unnecessary. Additionally, circular ties outperformed single-cross and double-cross lap-spliced crossties in terms of the confinement effect when the total confinement force is identical. Thirdly, single-cross crossties demonstrate higher confinement effects than double-cross crossties do, and the calculated reduction in the crossties' circular tie equivalent confinement force is correlated with the crossties' configuration pattern and confinement force ratio. Finally, RC circular columns with single-cross and double-cross crossties below 33% of confinement force percentage exhibit acceptable seismic performance, values shown later. These findings merit further research and clarification.