Difference Between Short Column and Long Column | What Is Column | Type of Column

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:
      (a) It encloses building areas into different compartments and provides privacy.
      (b) It provides safety from burglary and insects.
      (c) 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
    • Type of Loading
    • Slenderness Ratio
    • Type of Lateral Reinforcement 

  • Shapes of Cross-Section

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

  • Material of Construction

    • Timber Column
    • Masonry Column
    • R.C.C Column
    • Steel Column
    • Composite Column

  • Type of Loading

    • Axially Loaded Column
    • Eccentrically Loaded Column

  • Slenderness Ratio

    • Long Column
    • Short Column
    • Intermediate 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)
    • When the length of a column is more as compared to its c/s dimension, it is called a long column.
      • Le/r min > 50
      • Where,
        • Le. = Effective Length of Column
        • r min = Minimum radius of gyration

Also, read: Difference Between Lap Length and Development Length

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
      • Le/r main < 50

Or,

• • • • Le/d < 15
    • Crushing Load: The load at which a short column fails by crushing is called a crushing load.

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

Difference Between Short Column and Long Column

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

• • Type 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 condition
    • 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

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