SUPPORTED AREA FOR BEARING OF THE FOOTINGS AND LOADED AREA AT THE BASE OF THE COLUMN.

TRANSFER OF LOAD AT THE BASE OF COLUMN :-- The compressive stress in concrete at the base of a column or pedestal shall be considered as being transferred by bearing to the top of the supporting pedestal or footing .The bearing pressure on the loaded area shall not exceed the permissible bearing stress in direct compression multiplied by a value equal to A1/A2 under root but not greater than 2 where A1 Supporting area for bearing of footing, which is sloped or stepped footing may be taken as the area of the lower base of the larger frustrum of a pyramid or cone contained wholly within the footing and having for its upper base the area actually loaded and having side slope of one vertical to two horizontal and A2 is loaded area at the column base .Where the permissible bearing stress on the concrete in the supporting or supported member would be exceeded , reinforcement shall be provided for developing the excess force , either by extending the longitudinal bars in to the supporting member ,or by dowels.Where transfer of force is accomplished by reinforcement, the development length of the reinforcement shall be sufficient to transfer the compression or tension to the supporting member. In the case of extended longitudinal reinforcement or dowels of at least half percent of the cross sectional area (0.5) of the supported column or pedestal or a minimum of four bars shall be provided .Where dowels are used , their diameter shall not exceed the dia of the column bars by more than 3 mm .Column bars of diameter larger than 36 mm ,in compression only can be dowelled at the footings with bars of smaller size of the necessary area .The dowel shall extend into the column, a distance equal to the development length of the column bar and into the footing, a distance equal to the development length of the dowel .