Column can be defined as a vertical building element which transfer compressive load form beam or slab to the foundation and they pramarily use for the purpose of decoration. a column might transfer loads from a ceiling , floor or roof slab or from a beam, to a floor or
A column or pillar in architecture and structural engineering is a structural element that transmits, through compression , the weight of the structure above to other structural elements below. In other words, a column is a compression member. Wikipedia
Columns as load bearing structures:
A column is normally considered to be a vertical load bearing part of the structure. Its function is to carry gravity loads (dead loads of structure or live load i.e members of the family, including your large mother in law, warehouse goods, chairs, table etc). It could be made of concrete, steel, stone, brick, block, timber, wood, even ice if you live in the arctic, but with good compressive strength. Its shape could be round, square, rectangular. It can take any form you can imagine.
A column that carries the load down to a foundation must have means to transfer the load without overstressing the foundation material. Reinforced concrete and masonry columns are generally built directly on top of concrete foundations. When seated on a concrete foundation, a steel column must have a base plate to spread the load over a larger area, and thereby reduce the bearing pressure. The base plate is a thick, rectangular steel plate usually welded to the bottom end of the column.
Columns as decoration:
in architecture, a vertical element, usually a rounded shaft with a capital and a base, which in most cases serves as a support. A column may also be nonstructural, used for a decorative purpose or as a freestanding monument.
In the field of architectural design a column is used for decoration as well as support. Classical Greek and Roman architecture made use of five major orders (or styles) of columns, carved from single blocks or created from stacks of massive stone blocks. In ancient egypt and the middle east , columns, usually large and circular, were used with great effect to decorate and support massive structures, especially in the absence of arches. In eastern architecture, columns tend to be simple in shape but richly decorated. Modern columns tend to be made of iron, steel, or concrete.
Types of Column
Different types of column are discussed below including their function properties:
1. Classical stone columns: This type of columns are often highly decorated, with standard designs including Ionic, Doric and Corinthian, and so on.
2. Steel columns: This column have good compressive strength, but have a tendency to buckle or bend under extreme loading due to the followings;
- Cross-sectional area.
- Method of fixing.
- Shape of the section.
3. Slenderness ratio: This is the effective length of a column in relation to the least radius of gyration of its cross- section. If this ratio is not sufficient then buckling can occur.
Column slenderness can be classified as:
- Long or slender: This is when the length of the column is greater than the critical buckling length. Mechanical failure would typically occur due to buckling. The behavior of long
columns is dominated by the modulus of elasticity, which
measures a column’s resistance to being deformed elastically (i.e. non-permanently) when a force is applied.
4. Short: The length of the column is less than the critical buckling length. Mechanical failure would typically occur due to shearing.
5. Intermediate: This is in between the long and short columns, and its behavior is dominated by the strength limit of the material.
Classification will depend on the column ‘s geometry (i.e. its
slenderness ratio) and its material properties (ie. Young’s modulus and yield strength).
6. Shape: These column can be classified according to their cross sectional shape. Common column shapes include;
In profile, they can be tapered, non-tapered, or ‘barrel’ shaped, their surface can be plain, fluted, twisted, panelled, and so on.
Columns may be of a simple uniform design, or they may consist of a central ‘shaft’ sitting on a column base , and topped by a ‘capital’.
7. Reinforced concrete columns: These columns have an embedded steel mesh (known as rebar) to provide reinforcement.
The design of reinforcement can be either spiral or tied.
- Spiral columns are cylindrical with a continuous helical bar wrapped around the column . This spiral provides support in the transverse direction.
- Tied columns have closed lateral ties spaced approximately uniformly across the column. The spacing of the ties is limited in that they must be close enough to prevent failure between them, and far enough apart that they do not interfere with the setting of the concrete.