Important Point

## What Is Column?

A compression member, i.e., column, is an important element of** every reinforced concrete** **structure**. These are used to transfer a load of superstructure to the foundation safely.

**Mainly columns, struts, and pedestals are used as compression members in buildings, bridges, supporting systems of tanks, factories, and many more such structures.**

A column is defined as a vertical compression member who is mainly subjected to the **effective length and axial loads of which exceeds three times its least lateral dimension.**

The compression member whose **effective length is less than three times** its least lateral dimension is called Pedestal

The compression member who is inclined or horizontal and is subjected to axial loads is called Strut. Struts are used in trusses.

The function of columns is to transfer the load of the structure vertically downwards to transfer it to a foundation. Apart from the wall performs the following functions also:

- It encloses building areas into different compartments and provides privacy.
- It provides safety from burglary and insects.
- It keeps the building warm in cools in summer and winter.

Also, read: What is CBR Test in Civil

### Classification of Columns

A columns are classified based on different criteria such as:

**Shapes of Cross-Section****Material of Construction****Types of Loading****Slenderness Ratio****Types of Lateral Reinforcement**

**Shapes of Cross-Section**

**Square****Rectangular****Circular****Pentagonal****Hexagonal****Octagonal****T-Shape or L-Shape etc.**

**Material of Construction**

**Types of Loading**

**Axially Loaded Column****Eccentrically Loaded Column**

**Slenderness Ratio**

**Long Column****Short Column****Intermediate Column**

**What Is Short Column? **

When this ratio of **effective length to the least lateral dimensions** of **this column is less than** **12**, then it is knowns a short column.

(or)

When this ratio of effective length to the least radius of gyration is less than 45, then it is called a short column.When the length of the column is less as **compared to its c/s dimension**, it is called the Short column.

**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.

** l _{ef} / b ≤ 12**

l_{ef} = effective length

b = least lateral dimension of column

### What Is **Intermediate Column? | ****Intermediate Column**

Column is Intermediate

**30d > L > 4d**

and

**100 > Le / r min > 30or** Critical slenderness ratio.

Also, read: What Is Guniting, Set Guniting Systems , Advantage, Disadvantage

### What Is Long Column?

A long or slender column is the one whose ratio of effective length to its least lateral dimension is not less than 12. Then it is termed as a long column.

** l _{ef} / b ≤ 12**

**l _{ef} **= effective length

b = least lateral dimension of column

**Long Column**

When this ratio of **effective length** to the **least radius of gyration is greater than 45**, then it is called a** long column**.

A long column is subjected to a bending moment in addition to** direct compressive stress**. The load-carrying capacity of **a long column is less than a short column**.

The load-carrying capacity of **a long column depends upon slenderness ratio** (slenderness ratio increases then the capacity of the column decreases)

Also, read: Difference Between Lap Length and Development Length

## Difference Between Short Column and Long Column

Sr.No. |
Long Column |
Short Column |

1 | Long column is considered to be long if the ratio of effective length of column to its least lateral dimension is greater than 12. | Short column is considered to be short if the ratio of effective length to its least lateral dimension is less than or equal to 12. |

2 | Long column is weaker than a short column and generally, it is not preferred. | The short column is stronger than a long column and it is highly preferable. |

3 | Long column, whose lateral dimension is very small when compared to its length (or height), is called as long column. | Short column, whose lateral dimension is very large when compared to its length (or height), is called a short column. |

4 | It is generally fails by buckling. | It generally fails by crushing. |

5 | The slenderness ratio is greater than 45. | The slenderness ratio is less than 45. |

6 | As the height of column increases the load carrying capacity is less. | As the height of the column decreases the load-carrying capacity is more. |

7 | Long Column Radius of gyration is less. | Short column radius of gyration is more. |

8 | Load carrying capacity is less. | Load-carrying capacity is more. |

9 | Long column is subjected to buckling stress | The short column is subjected to compressive stress. |

10 | Long and slender columns buckle easily. | The buckling tendency is very low. |

11 | The ratio of effective length of a long column to its least radius of gyration is greater than 40. | The ratio of the effective length of a short column to its least radius of gyration is less than or equal to 40. |

12 | The failure of the short column is by crushing. | The column generally fails in buckling. |

Also, read: What Is Lap Length | Lap Length of Column | Lap Length of Slab | Lap Length of Beam

**Types of Lateral Reinforcement **

- A column with Lateral Ties.
- A column with Helical Ties.

Also, read: Difference Between Footing and Foundation | What is Footing and Foundation

## Failure Mode of Column

- A column can fail in one of three conditions.
- Compression failure of concrete or steel reinforcement.
- Buckling.
- Combination of compression and buckling failure.
- Compression failure is likely to occur with columns that are short and stocky.
- Buckling is probable with a column which is long and slender.

### Long Column

Long column a column so slender that it will fail under longitudinal load by bending rather than by crushing and typically having a **length of 20 to 30 times the diameter**.

### 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.

### Slender Column

Slender columns can be defined as columns with small cross-sections compared to their lengths. Generally, slender columns have lower strength when compared to short columns, for a constant cross-section, increasing the length causes a reduction in the strength. The behaviour of slender column.

### Strut and Column

Both column **and Strut is a comprehensive member** but main difference between two is column is comprehensive member of frame structure and strut is comprehensive member of truss structure.

### Column and Struts

A structural member subjected to axial compressive force is called a strut. **When a strut is vertical it is known as column**. The cross-sectional dimensions of a column are large.

### Short Column Effect

Stiffness of a column means resistance to deformation – the larger is the stiffness, larger is the force required to deform it. If a short column is not adequately designed for such a large force, **it can suffer significant damage during an earthquake**. This behaviour is called Short Column Effect.

### Column Dimensions

Sr.No. |
Structure |
Number of Storey |
Column Size (mm) |

1 | 10 storey building | 1 to 10 | 700 x 700 |

2 | 20 storey building | 1 to 7 | 750 x 750 |

8 to 14 | 600 x 600 | ||

15 to 20 | 450 x 450 | ||

3 | 30 storey building | 1 to 10 | 800 x 800 |

11 to 20 | 650 x 650 | ||

21 to 30 | 470 x 470 |

### Long Column Design

Long column usually stands for the column in which the ratio of effective length of the column to the minimum lateral dimension of the column is in excess of 12.

### Short and Long Column

Short columns have a large lateral dimension as compared to its height. Long columns have a small lateral dimension as compared to its height. The short column is stronger than a long column and it is highly preferable. Long column is weaker than a short column and generally, it is not preferred.

### What Is Slenderness Ratio of Beam?

Slenderness ratio is defined as **the ratio of effective length to the radius of gyration of beam**. Sl ratio(Lamda)= L/r. Where r=I/A. I= moment of inertia. A= Area of beam.

### What Is the Formula for Slenderness Ratio?

The slenderness ratio is calculated by **dividing the column length by its radius of gyration.**

### What Is Lateral Dimension of Column?

Column is a vertical compression member whose unsupported length l shall not exceed sixty times of b (least lateral dimension), if restrained at the two ends. Further, its unsupported length of a cantilever column shall not exceed 100b2 /D, where D is the larger lateral dimension which is also restricted up to four times of b (vide cl. 25.3 of IS 456 and Fig.10.21.1b).

### Slenderness Ratio of Column

The slenderness ratio is defined as **the ratio of length l to the radius of gyration k**, represented as l/k. When the slenderness ratio exceeds a value of 100 for a strong slim column, failure by buckling can be expected. Columns of stiffer and more brittle materials will buckle at lower slenderness ratios.

### Difference Between Long Column and Short Column

The **column**, whose lateral dimension **is** very small when compared to its length (or height), **is** called a **long column**. The **column**, whose lateral dimension **is** very **large** when compared to its length (or height), **is** called a **short column**. It **is generally failed** by buckling.

### Lateral Dimension of Column

A **column** is defined as a compression member, the effective length of which exceeds three times the least **lateral dimension**. Compression members whose lengths do not exceed three times the least **lateral dimension** may be made of plain concrete.

### What Is Difference Between Long Column and Short Column?

The **column**, whose lateral dimension is very small when compared to its length (or height), is called as **long column**. The **column**, whose lateral dimension is very **large** when compared to its length (or height), is called a **short column**.

### Slenderness Ratio of Short Column

If **slenderness ratio is less than 12**, it is called as short **column**, if SR is **greater than 12**, it is long **column.**

### Slenderness Ratio of Long Column

A **long** or slender **column** is the one whose **ratio** of effective length to its least lateral dimension is not less than 12. Then it is termed as a **long column**.

### Long Column and Short Column

Short columns have a large lateral dimension as compared to its height. Long columns have a small lateral dimension as compared to its height. The **short column is stronger than a long column** and it is highly preferable. Long column is weaker than a short column and generally, it is not preferred.

### Slenderness Ratio of Short Column

Sr.No. |
Short Columns |

1 | They are subjected to compressive stresses. |

2 | Its slenderness ratio is less than 45. |

3 | Short columns have a large lateral dimension as compared to its height. |

4 | The short column is stronger than a long column and it is highly preferable. |

### Effective Length of Column Definition

The effective length (or Le or KL) of a column is defined as **the distance between successive inflection points or points of zero moment.**

### Difference Between Short Column and Long Column

Short columns have a large lateral dimension as compared to its height. Long columns have a small lateral dimension as compared to its height. The **short column is stronger than a long column** and it is highly preferable. Long column is weaker than a short column and generally, it is not preferred.

### What Is Short and Slender Column?

A short column is defined as **one in which the ultimate load is not reduced by the bending deformations** because the additional eccentricities Δ=e2 are negligible. A slender column is defined as one in which the ultimate load is reduced by the amplified bending moment caused by additional eccentricity.

### What Is Equivalent Length of Column?

The equivalent or effective length is defined as **the distance between two adjacent points of contra flexure on the column**. The equivalent length of a column is usually given in terms of the actual length and depends upon the end conditions of the column.

### What Is the Long Column?

Long column is a column so slender that it will fail under longitudinal load by bending rather than by crushing and typically having a **length of 20 to 30 times the diameter.**

### How Do You Create a Short Column?

There are some steps are as follows.

Step 1: To check the slenderness ratio

Step 2: Minimum eccentricity

Step 3: Area of steel

Step 4: Lateral ties

### Which Section Is Best for Long Column?

The rectangular column circular section is the best.

### What Is Short Column Effect?

Stiffness of a column means resistance to deformation the larger is the stiffness, larger is the force required to deform it. If **a short column is not adequately designed for such a large force, it can suffer significant damage during an earthquake**. This behaviour is called Short Column Effect.

### How Long Is a Column?

In the United States, a common newspaper column measurement is **about 11 picas wide** —about 1.83 inches (46 mm)—though this measure varies from paper to paper and in other countries.

### What Is Short Column Failure?

Short column **posses high stiffness that attracts most of the force acting on the multi-story building**. Inadequate design of short column to sustain these forces will result in damage and shear failure. This behaviour of the short column under excessive force is called as short column effect.

### What Shape Column Is the Strongest?

The strongest column has **an equilateral triangle as cross section**, and it is tapered along its length, being thickest in the middle and thinnest at its ends. Its buckling load is 61.2% larger than that of a circular cylinder.

### What Is Column Neck?

It is **a part of the column (any type of column)** which is buried in earth is called Neck column. The word Neck column is usually used while building footings.

### What Is Difference Between Long Column and Short Column?

The column, whose lateral dimension is **very small** when compared to its length (or height), is called a long column. The column, whose lateral dimension is very large when compared to its length (or height), is called a short column.

### What Is Difference Between Column and Strut?

Both column and Strut **is comprehensive member** but main difference between two is column is comprehensive member of frame structure and strut is comprehensive member of truss structure. But strut is subject to only axial force that is compressive force.

### What Is Effective Length of Column?

The effective length (or Le or KL) of a column is defined as **the distance between successive inflection points or points of zero moment.**

### What Is Medium Column?

Columns which have their **lengths varying from 8 times their diameters to 30 times their diameters** or their slenderness ratio **lying between 32 and 120**. In these columns, both bucklings as well as direct stresses are of significant value.

### What Is Pitch in Column?

The pitch of reinforcement means **the spacing of reinforcemt**. This particular word pitch indicates the spacing of ring in circular columns.

### What Is Slenderness of Column?

The length of a column is the distance between points unsupported against lateral deflection. The slenderness ratio is **the length l divided by the least radius of gyration k.** Various conditions may exist at the ends of columns that usually are divided into four classes.

### What Is Column and Types?

There are several types of columns which are used in different parts of structures. **Column is a vertical structural member that carry loads mainly in compression**. It might transfer loads from a ceiling, floor slab, roof slab, or from a beam, to a floor or foundations. … Types of Columns in Building Construction.

### How Columns Are Classified?

Columns are classified into the following two types based on the slenderness ratios: (i) **Short columns** (ii) **Slender or long columns** presents the three modes of failure of columns with different slenderness ratios when loaded axially.

### What Is the Maximum Height of Column?

The maximum height of a column is **24 m**.** Columns height from 20 m to 24 m** can be manufactured as one piece (uncut), and composite.

### Is Column a Strut?

Both **column and Strut is comprehensive member** but main difference between two is column is comprehensive member of frame structure and strut is comprehensive member of truss structure. But strut is subject to only axial force that is compressive force.

### What Is Difference Between Column and Pillar?

A pillar is a **vertical support** member and may be constructed as a single piece of timber, concrete or steel, or built up out of bricks, blocks and so on. However, whereas a pillar does not necessarily have a load-bearing function, a column is a vertical structural member that is intended to transfer a compressive load.

### What Is a Strut Structure?

A strut is **structural member that is being pushed from opposite ends**. It is said that a strut “resists compression.” Since they are used to hold up the weight of a structure and to resist the external loads pushing down upon them columns are always in compression.

### How Do You Know If a Column Is Slender?

Slender columns can be defined as **columns with small cross sections compared to their lengths**. Generally, slender columns have lower strength when compared to short columns, for a constant cross section, increasing the length causes a reduction in the strength.

### Where the Short Column Is Used?

The short columns are stiffer compared to long columns and hence **most of the earthquake forces acting on the building** are taken by the short columns. More the stiffness of any structural element, less will be its flexibility to undergo any sort of deformation.

### What Are the Basic Differences Between Short Column and Long Column?

The column, whose **lateral dimension is very small when compared to its length (or height)**, is called as long column. The column, whose lateral dimension is very large when compared to its length (or height), is called a short column.

### What Is Buckling of Column?

Buckling of Columns is **a form of deformation as a result of axial- compression forces**. This leads to bending of the column, due to the instability of the column. This mode of failure is quick, and hence dangerous. This will occur at stress level less than the ultimate stress of the column.

### When the Slenderness Ratio Is Less Than 12 a Column Is?

If slenderness ratio is less than 12, it is called as short column, if **SR is greater than 12**, it is long column.

### What Type of Column Is the Strongest?

The **cylindrical shaped column** was by far the strongest column and supported the most weight. The cylindrical shaped column is the strongest is because of corners. The flat sides of the shapes do not support structural load. Therefore, it is the corners of the shapes that give the columns their strength.

### Which Is Column Section?

The term column applies especially to a **large round support** (the shaft of the column) with a capital and a base or pedestal, which is made of stone, or appearing to be so. A small wooden or metal support is typically called a post, and supports with a rectangular or other non-round section are usually called piers.

### What Is Effective Length?

The shortest distance between the top and bottom most points of the column at the point of bending is termed as length which effectively resists against the buckling.

### Can a Column Rest on a Beam?

The floating column is a vertical member which rest on a beam but doesn’t transfer the load directly to the foundation. The column may start off on the first or second or any other intermediate floor while resting on a beam. Usually columns rest on **the foundation** to transfer load from slabs and beams.

### How Do You Find a Column Buckling?

The Euler column formula predicts the critical buckling load of a long column with pinned ends. The Euler formula is **P cr = π 2 ⋅ E ⋅ I L 2** where E is the modulus of elasticity in (force/length^{2}), I is the moment of inertia (length), **L** is the length of the column.

### How Do You Stop Column Buckling?

To prevent buckling the easiest way is to reduce the length in some form or to change the shape of the cross section. The length reduction can be done by **the use of a brace** (Winter, 1958). The brace can either be considered to be elastic or ideal.

### How Do I Design the Size of a Column?

The thumb rules are for general designing in very small projects. For this general thumb rule, we will assume a structure of G+1 floors high, using standard **6″ walls**. Minimum size of an RCC column should not be **less than 9” x 12” (225mm x 300mm)** with **4 bars of 12 MM Fe415 Steel**.

### How Do You Find the Height of a Column?

The height of the column containing packing is usually calculated by **Z = (NTP) (HETP)**, where (HETP) = **Height of Packing Equivalent to One Theoretical Plate**.

### What Is Short Column and Long Column?

If the ratio of effective length to its least lateral dimension is less than or equal to 12 then it is called short 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.

### What Are the Basic Differences Between Short and Long Column?

Long column is considered to be long if the ratio of effective length of column to its least lateral dimension is greater than 12. Short column is considered to be short if the ratio of effective length to its least lateral dimension is less than or equal to 12.

### How Do You Know If Long Column or Short Column?

Long column is considered to be long if the ratio of effective length of column to its least lateral dimension is greater than 12. Short column is considered to be short if the ratio of effective length to its least lateral dimension is less than or equal to 12.

### How Is Euler Buckling Calculated?

The Euler column formula predicts the critical buckling load of a long column with pinned ends. The Euler formula is **P cr = π 2 ⋅ E ⋅ I L 2** where E is the modulus of elasticity in (**force/length ^{2}**), I is the moment of inertia (length

^{4}), L is the length of the column.

### What Is a Column Structure?

A column is **a vertical structural member intended to transfer a compressive load**. Columns are typically constructed from materials such as stone, brick, block, concrete, timber, steel, and so on, which have good compressive strength.

### What Is the Strongest Shape Experiment?

We tried the experiment twice and both times found **the circular column** to be the strongest. This is because it doesn’t have any edges so the weight of the books is shared evenly by the circle. The square and triangle support the books on their edges and corners meaning they collapse.

### What Is the Slenderness Ratio of a Column?

The slenderness ratio is defined as the ratio of length l to the radius of gyration k, represented as l/k. When the slenderness ratio exceeds a value of 100 for a strong slim column, failure by buckling can be expected. Columns of stiffer and more brittle materials will buckle at lower slenderness ratios.

### What Is Slenderness Ratio and Effective Length?

The effective length is calculated from the actual length of the member considering the rotational and relative translational boundary conditions at the ends. Slenderness captures the influence on buckling of all the geometric aspects of the column, namely its length, area, and second moment of area.

### What Is Euler’s Formula for Column?

The Euler column formula predicts the critical buckling load of a long column with pinned ends. The Euler formula is **P cr = π 2 ⋅ E ⋅ I L 2** where E is the modulus of elasticity in (force/length^{2}), I is the moment of inertia (length^{4}), L is the length of the column.

### What Is the Effective Length of a Column?

The effective length (or** Le or KL**) of a column is defined as the distance between successive inflection points or points of zero moment.

### What Is a Good Slenderness Ratio?

These values can be found in the American Institute of Steel Construction (AISC) manual and typically range **between 0.5 and 2.0**. The value of K depends on how the ends of the column are supported in a given structure, that is, on the nature of their attachments.

### What Is the Equation of Slenderness Ratio?

Using the radius of gyration, the critical stress developed in a long column at buckling can be expressed by the following equation. **fcritical = Pcritical/A = π2EImin/AL2 = π2E(Ar2)/AL2 = π2E/(L/r)**2 The term “**L/r**” is known as the slenderness ratio.

### What Is Buckling Factor?

The buckling load factor (BLF) is the factor of safety against buckling or the ratio of the buckling loads to the applied loads.

### What Is the Ratio of Factor of Safety?

The ratio of the maximum stress that a structural part or other piece of material can withstand to the maximum stress estimated for it in the use for which it is designed. Also called safety factor.

### What Is the Slenderness Ratio of a Long Column?

A long or slender column is the one whose ratio of effective length to its least lateral **dimension is not less than 12**. Then it is termed as a long column.

### What Is Lateral Dimension of Column?

Column is a vertical compression member whose unsupported length l shall not exceed sixty times of b (least lateral dimension), if restrained at the two ends. Further, its unsupported length of a cantilever column shall not exceed **100b ^{2} /D**, where

**D**is the larger lateral dimension which is also restricted up to four times of

**b**.

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