There are several reasons behind using ties. The following are the main reasons behind using ties in column.
- Longitudinal bars are confined by transverse steel tie bars in order to maintain their positions.
- At the time of concreting it prevent movement of main reinforcement.
- In order to prevent buckling of column and bursting of lateral reinforcement into the concrete cover under the vertical forces (compression force) specially in the middle of the column by holding the longitudinal bars in position.
- It improves the ductility of column.
- It also improve dowel action of column reinforcement.
- The lateral ties also confined the concrete, thereby enhancing it’s compression load-bearing capacity.
Spacing between the lateral ties as per IS 456
Spacing between two adjacent lateral tie is also called as pitch.
The pitch of transverse reinforcement shall be not more than the least of the
i) The least lateral dimension of the compression members;
ii) Sixteen times the smallest diameter of the longitudinal reinforcement bar to be
iii) 300 mm.