Details of Reinforcement in Columns
Usually, concrete columns contain square, rectangular or circular cross sectional area. To get rid of buckling of the main bars, columns are necessary for the primary longitudinal reinforcement and lateral ties. Buckling results in splitting of concrete. The primary reinforcement in columns is equal to the direction of the load. Reinforcement is provided with the aim of minimizing the column size.
The detailed information for smallest and highest limits of reinforcements, least no. of bars, the size of bars, necessity of cover, diameter and spacing are provided below:
For the RC columns that comprise of helical ties, 6 basic longitudinal reinforcements should be provided to the helical support. Allocate the reinforcement evenly on four sides of the RC columns.
The positioning of the longitudinal reinforcement should not surpass 300 mm. The highest and lowest values of the pitch of helical reinforcement is limited to 75 mm and 25 mm. Helically reinforced portions contain significantly superior load bearing limit as compared to those containing common lateral ties due to greater degree control of concrete in the centre.
The number of bars in a column range from 10, 12, 14, 16 of changeable diameter. These offer various diameter main bars like 16mm, 20mm, 25mm. Toward circular column, these offer 6 nos 20mm dia and 6 nos 16mm dia.
The operative length given is 48 times the dia of bar.
Article Source : www.dailycivil.com