The correct answer is: D. Lesser of the above three values.
The minimum pitch of transverse reinforcement in a column is the least of the following three values:
- The least lateral dimension of the member.
- Sixteen times the smallest diameter of longitudinal reinforcement bar to be tied.
- Forty-eight times the diameter of transverse reinforcement.
The minimum pitch of transverse reinforcement is important to ensure that the column is able to withstand the forces acting on it. If the pitch is too small, the reinforcement will not be able to distribute the forces evenly, and the column may fail.
The least lateral dimension of the member is the smallest dimension of the column in the direction of the applied loads. This is the most important factor in determining the minimum pitch of transverse reinforcement, as it is the dimension that will control the amount of lateral movement of the reinforcement.
The smallest diameter of longitudinal reinforcement bar to be tied is the diameter of the smallest longitudinal reinforcement bar in the column. This is important to consider, as the diameter of the longitudinal reinforcement bar will affect the amount of space available for the transverse reinforcement.
Forty-eight times the diameter of transverse reinforcement is a conservative value that is used to ensure that the transverse reinforcement is able to withstand the forces acting on it. This value is typically used in cases where the other two factors are not known or cannot be determined.
In general, the minimum pitch of transverse reinforcement should be as small as possible to ensure that the column is able to withstand the forces acting on it. However, the pitch should not be so small that it interferes with the placement of the longitudinal reinforcement or the concrete.