Difference between Lap Length and Development Length in Bar Bending Schedule

Lap length and development length used in bar bending schedule. These are the extensions provided in the bar to transfer the load safely to the bars without any loss.
Lap length :- The length of the steel bar is 15m in the factory. If the steel bar is increased more than its limit of 15m? Then for transferring the load safely, two bars are overlapped.
So simply the overlapping of two bars to increase the length of the rebar and to transfer the load from one rebar to another is known as “Lap Length.”
Lap length depends upon type of member :-
For the compression member, the lap length is 40D
For the tension member, the lap length is 50D

Development length
The load carried by rebar is transferred to the surrounding concrete is called the development length and it is also known as Anchorage Length.
Development Length is denoted as Ld
It is generally provided in Slabs, Continuous beams and at column-beam joints.
As per IS 456:2000, the tension or compression member at any point should be increased on each side of the section by providing a proper development length. If we provide the development length the bar won’t slip away from the support.
It is also provided when a bar resisting a force is removed. In these scenarios, it is compulsory to carry this force in the bar to the surrounding concrete over a particular length.