Column reinforcement

The load of a particular level is transferred to the foundation by the columns which require the columns to have a high compression capacity yet the tension capacity is also important as the loads due to lateral load like wind load may also be borne by these. First the vertical bars positioned according to the column size and drawings. The first vertical bars fixed at the ground level. After that the stirrups are inserted from the top of the reinforcement cage and are bound at the specified spacing. The starter bars have to be kept for the column at next level with at least one lap length. Where the column size is reduced at a particular level docking has to be done,

A column is a slender, vertical member that carries a superimposed load. When the structure’s height is less than three times its least lateral dimension, this structure is known as a pier or pedestal . Concrete columns must always have steel reinforcement because they are subject to bending. Figure  shows two types of column reinforcement. Vertical reinforcement is the main type. Lateral reinforcement consists of individual ties or a continuous spiral that surrounds the column.

The steel reinforcement in columns is designed primarily to sustain compressive stress to reinforce the compressive strength of concrete, but also to reinforce the poor tensile strength of concrete against tensile stress due to bending from fixed end beams, eccentric loading and wind pressure.

Column-reinforcement 02

Typical  shapes  of  reinforcing  steel

Spiral columns – Spiral columns a spiral column is a round column that has a continue spiral winding of lateral reinforcement encircling its core and vertical reinforcement bars to restrain expansion. A spiral column is generally considered to be stronger than a tied column. the spiral reinforcement is superior to the many imperfect anchorages that are at the ends of the individual lateral ties in a tied column. The pitch of the spiral reinforcement  can be reduced to provide more effective lateral support. the design engineer specifies the pitch of the spiral, the tie size, and the number of vertical bars for a spiral column.