What Is Column?
A member that is arranged anywhere in the structure and has a compressive load on a member with less cross-section in length is called a column.
Columns and struts are used as compression members in heavy construction, in the construction of buildings, bridges, auxiliary systems of tanks, factories, etc.
According to IS CODE 456-1978, the effective length of a vertical column is three times the value of the minimum size of its cross-section.
The column is a structural element as a compression member in architecture and structural engineering, which transfers the external load of the structure to the other structural elements below. For wind or seismic engineering purposes, the column can be designed to resist external forces.
Columns are used in building structures to support beams or arches, which support the upper part of the walls or ceiling. In architecture, structural elements such as “columns” can be used for decorative features.
Also Read : What Is Beam? | What Is Column? | Difference Between Beam and Column
What is a Short Column?
When the ratio between the minimum size of the compression member’s cross-section and its effective length is less than 12, this compression member is known as a short column.
lef / b ≤ 12
lef = effective length
b = least lateral dimension of column
When the ratio between the effective length of the compression member and the radius of gyration of the cross-section of that member is less than 45, that member is then called the short column.
Lef/r <45
lef = effective length
r =radius of gyration
Also Read : What is the Plinth Beam? | Application of Plinth Beam | Specification of Plinth Beam | Plinth Protection
What Is a Long Column?
When the ratio between the minimum size of the cross-section of the compression member and its effective length is greater than 12, this compression member is known as a long column.
lef / b ≥ 12
When the ratio between the effective length of the compression member and the radius of gyration of the cross-section of that member is greater than 45, that member is then called the long column.
Le/r >45.
Classification of Columns
Columns are categorized according to different criteria
- Shapes of Cross-Section
- Types of Loading
- Material of Construction
- Slenderness Ratio
- Types of Lateral Reinforcement
Shapes of Cross-Section
- Square
- Rectangular
- Circular
- Pentagonal
- Hexagonal
- Octagonal
- T-Shape or L-Shape etc.
Types of Loading
- Axially Loaded Column
- Eccentrically Loaded Column
Material of Construction
- Timber Column
- Masonry Column
- R.C.C Column
- Steel Column
- Composite Column
Slenderness Ratio
- Long Column
- Short Column
- Intermediate Column
Types of Lateral Reinforcement
- A column with Lateral Ties.
- A column with Helical Ties.
Reason of the Column Is Failure
- The most common cause of column failure is compressive stress. The only reason for short column failure is the crushing stress it produces.
- Short column and long column fail due to buckling.
- Combination failure caused by buckling and crushing occurs only in the case of the intermediate column.
Also Read : What Is a Dead Load? | What Is Live Load? | Difference Between Dead Load Vs Live Load
Difference Between Short Column and Long Column
| Sr no | Short columns | Long columns |
| 1 | If the ratio between the effective length and its minimum side cross-section is less than 12, it is called a short column. | If the ratio between the effective length and its minimum side cross-section is larger than 12, it is called a long column. |
| 2 | Due to the low height of the short column, the load-carrying capacity of the column is high | Due to the high height of the long column, its carrying capacity is low |
| 3 | short columns are subject to compressive stresses. | long columns are subject to buckling stresses. |
| 4 | The tendency to buckling in the short column is very low. | Long and cylinder columns tend to buckle easily. |
| 5 | The tendency of crushing in the short column is very high. | The tendency to crush in a long column is very low |
| 6 | A short column has more load-carrying capacity than a long column with the same cross-section. | Long columns have less load-carrying capacity than short columns with the same cross-section. |
| 7 | The failure of the short column is due to the buckling that occurs in it. | Fails due to crushing occurring in a long column |
| 8 | In a short column, the effective length of the least radius of the gyration ratio is less than 40. | In a long column, the effective length of the least radius of the gyration ratio is greater than 40. |
| 9 | Short columns have more radius of gyration. | long columns have less radius of gyration. |
| 10 | The slenderness ratio in the short column is less than 45. | The slenderness ratio in the long column is greater than 45. |
| 11 | The cross-section of a short column is larger than a long column. | The cross-section of a long column is less than a short column. |
| 12 | A short column is stronger than a long column | Long columns are weaker than short columns; they are usually avoided. |
Also Read : What Is Pitched Roof? | Types of Pitched Roof | Advantage & Disadvantage of Pitched Roof
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Frequently Asked Questions (FAQ)
What Is a Column in Construction?
Types of Columns in Construction:
- Concrete Columns.
- Column.
- Tension Columns.
- Composite Columns.
- Braced Columns.
What Do You Mean by a Short Column?
A short column is the one whose ratio of effective length to its least lateral dimension is less than or equal to 12. Then it is termed as a short column.
Where the Short Column Is Used?
Short column effect is also observed in the columns that support loft slabs or mezzanine floors. These elements are added between two existing floors. Another case is the presence of short and long column on the same floor level.
Where Are Long Columns Used?
They are commonly used in the construction of buildings and heavy structures. It is much effortless to construct and cast rectangular or square columns than circular ones. The square or rectangular ones are better and cheapest in cost.
Where the Short Column Is Used?
Short column effect is also observed in the columns that support loft slabs or mezzanine floors. These elements are added between two existing floors. Another case is the presence of short and long column on the same floor level.
What Is the Effective Length of the Column?
If the ratio of the effective length of the column to its least lateral dimension is greater than 12 then it is called a long column. The effective length to least radius of gyration ratio is less than or equal to 40.