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In reinforced cement concrete construction, lap splices are not recommended to be used for rebars when the bar diameter is more than:

In reinforced cement concrete construction, lap splices are not recommended to be used for rebars when the bar diameter is more than: Correct Answer 32 mm

Explanation:

Lap splice:

  • It is done by overlapping the bars over a certain length, thereby making possible the transfer of axial force from the terminating bar to the connecting bar by the mechanism of anchoring (development) bond with the surrounding concrete.
  • Lap splices are generally not permitted for very large diameter bars (ϕ > 32 mm), for which welded splices are recommended.

Confusion Points 

  •  According to 3rd amendment of IS 456: 2000 in 2007, the value was changed from 36 mm to 32 mm.
  • So, 36 mm is an old provision and 32 mm is a new provision

Additional Information 

  • However, where welding is not practicable, CI. 26.2.5.1(a) of IS 456:2000 recommends the use of additional spirals around the lapped bars.
  • It is always desirable to bend the bars slightly (especially for large diameter bars) at the location of the splice in order to have a collinear force transfer without any eccentricity.
  • As per IS 456, the straight length of the lap should not be less than 15ϕ or 200 mm (whichever is more).
  • The lap length must be at least equal to the development length.
  • In no case, the lap length should be less than 30ϕ for flexural and direct tension and 24ϕ for compression.
  • When two different diameter bars meet at the splice location then lap length should be calculated based on the smaller bar diameter.
  • Splices in tension members should be enclosed by spirals made up of bars of diameter not less than 6 mm along with pitch not exceeding 100 mm

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