In Column reinforcement details we will talk about the Requirement of Longitudinal Reinforcement and Lateral Reinforcement of a Column.
The column is defined as a vertical compressive member that is subjected to a compressive force. It shall be called a column if its effective length will be three times the least lateral dimension.
If the effective length of the column is not at least three times its lateral dimension then it is known as Pedestal. The inclined column subjected to axial loading is known as Strut.
Types of Reinforcement in Column
- Longitudinal Reinforcement
- Lateral or Transverse Reinforcement
1) Longitudinal Reinforcement
The Steel Rod placed longitudinally in a column is known as Longitudinal reinforcement. It is also known as the main rod of a column.
Function of Longitudinal Reinforcement
- It spread the compressive load to concrete.
- It resists Tensile Stress.
- It Provides Ductility to the column.
- It reduces the effect of shrinkage.
2) Lateral or Transverse Reinforcement
The steel rod provided along the lateral dimension of the column is known as lateral or Transverse reinforcement.
Function of transverse Reinforcement.
- It prevents buckling of the column due to excess load.
- It holds all the main or transverse reinforcement.
- It Resists horizontal or diagonal tension on the column.
Types of Lateral Reinforcement
Column with lateral ties
Column with Spiral ties
Column reinforcement details- As Per- IS456-2000
The nominal cover for a longitudinal reinforcement bar in a column should not be less than any of the following,
A) 40 mm
B) The diameter of the bars
The Minimum eccentricity to design a column should be,
Requirement of Longitudinal Reinforcement of Column
1. The cross-sectional area of longitudinal reinforcement in a column should not less than 0.8 percent and more than 6 percent of the gross cross-sectional area of the column.
2. The minimum numbers of longitudinal bars in a column should not be less than four in the rectangular column and less than six in a circular column.
3.The longitudinal bars should not be less than 12 mm in diameter.
4.The spacing of longitudinal bars should not be more than 300 mm.
Requirement of Lateral Reinforcement of Column
1.The diameter of lateral ties should be greater among,
- (¼)th of the diameter of the largest longitudinal bars.
- 6 mm
2. The Pitch or spacing of the lateral ties should not be greater than the following.
- Least lateral dimension of the column.
- 16 times the diameter of the smallest longitudinal bars.
- 300 mm
3. The diameter of spiral or helical reinforcement bars should be greater among,
- (1/4)th of the diameter of the largest longitudinal bar.
- 6 mm
4. The pitch of spiral reinforcement should not be more among,
- 75 mm
- (1/6)th of the diameter of the core of concrete.
Effective length of Column- Under Different condition of Fixed-Rotation