Lapping length

What is lapping & development length and why it is provided?

Lap length :

Over lapping length or development length is provided for maintain the continuity of bar in order to safely transfer the stress from one bar to another bar.

Lap length should not be less than 75mm. Generally we take 24d-50d, Where d is the diameter of bar as IS 456-2000.

Lap always provided of upper bar and in position of it should be inside, So we don’t have to change the clear cover.

Things to take care while providing a lap length in column :

  • Lapping should be provided at centre of column because bending moment at mid point is zero so try to lap at mid point.
  • lapping of bar should be provided alternatively. Lap should not be given at same point because buckling may occur.
  • After 32mm diameter of bar it should be welded.
  • Due to maximum stress we can’t lap at column/ beam/ slab joint. Lapping should not be given at L/4 distance from top and bottom of the support.

Things to take care while providing a lap length in beam :

  • Lapping in top bars avoided L/3 distance from both end. For top bar lapping should be at mid span.
  • Lapping in bottom bars lap should be provided at column junction or L/4 distance from column face but shouldn’t be in mid span of beam.
  • Lapping of bars should be alternatively provided.

Development length :

Development length is provided to transfer the stress from steel to concrete from one binding component to other. Development length is also known as ‘anchorage length”.

Read more:

What is bar bending schedule and advantages of BBS?

What are the benefits of making a wall using interlocking bricks?

Post Author: hemantduva

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