Difference Between Lap Length and Development Length | Steel Bar Formula | Development Length Calculations | Overlapping in Reinforcement
In this Article today we will talk about the Difference Between Lap Length and Development Length | Steel Bar Formula | Development Length Calculations | Overlapping in Reinforcement.
The main purpose of providing reinforcement bars is to transfer the load from member to member. It may be either to another rebar or to concrete.
In Order to successfully transfer the load from one member to another, reinforcement bars need to be firmly tied at both ends so that it can’t be slipped away.
All the extensions or extra lengths provided in reinforcement has the same purpose.
” To transfer the load safely to another member without any fail”

Are you clear about that? Fine.
Lap Length :-
Due to the limited length of bar, lapping of bars are required in a member of more than 12m in length or where length of bar required is more than 12m.

Lap Length:- Length of bar required to transfer the stress safely.
or
Lap Length:- Overlapping Length or Lap Length is provided for maintain the continuity of bars in order to safely transfer the load from one bar to another bar. It depends on the Grade of Concrete, grade of steel and dia. of bar.
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Development Length :-
Development Length:- Development Length is provided to transfer the load from steel to concrete. Development Length is also known as anchorage length.

According to IS 456:2000, the calculated tension or compression in any bar at any section shall be developed on each side of the section by providing appropriate development length or by an end anchorage. So that the member won’t be slipped away from the support.
Such length will be provided in a continuous beam, cantilever slabs and other critical joints (beam-column). It will be provided as a bend where the restraining member is thin like as an end beam as shown below (Ld).

Conclusion:
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