This construction video tutorial sheds light on reinforcement lapping zone in column. By going through this video, one can learn how to place lap in exact position in column by adhering to IS code 13920.
A lap is required when two pieces of reinforcing bar (rebar) are overlapped to produce a constant line of rebar. The length of the lap fluctuates according to the concrete strength, the rebar grade, size, and spacing.
The objective of lap is to transmit load from one bar to another bar as well as retain continuity. The positioning of lap is dependent on the bending moment of the column.
Lap length refers to the length of the overlap of bar necessary to securely transmit stress from one bar to another. Lap length varies on the basis of tension and compression zones and mostly relies on grade of concrete and steel. Development length refers to the length of the bar necessary to transmit stress from steel to concrete.
Rebars in column should have been lapped at around 5 feet from the story.
As stated by I.S. 13920 Vertical bars of Columns should be lapped in regular zone (Mid-height ) only and it should be spread out i.e. not surpassing 50% of bar is lapped at one section. Besides, lowest clear vertical distance among lapped bars should be 0.25 times lap length.
To get more details, watch the following video tutorial.
Video Source: Sami Ullah Stanikzai