In earthquake design of columns, 135-degree hook anchorages are required in peripheral hoops and crossties to assure the ductility of columns. However, 135-degree hook anchorages frequently cause difficulty in reinforcing bar placement.
In the present study, V-shaped ties were studied to partially replace conventional transverse reinforcement. Their details and layout were also proposed. To verify the effect of V-ties, cyclic lateral loading tests were performed for six columns using conventional transverse reinforcement or V-ties. The test results showed that V-ties successfully restrained buckling of longitudinal reinforcement and provided lateral confinement to the core concrete.
However, the deformation capacities of columns with V-ties were slightly less than those of columns with crossties because V-ties do not provide shear resistance. Thus, for special moment frames with high shear demand and ductility demand, the vertical spacing of perimeter hoops should be reduced. On the basis of the test results, design considerations for columns with V-ties were recommended.