Question

how to prepare lap length
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Answer 1

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$Lap length is one of the important term in the reinforcement. This is usually confused with another important term called development length and anchorage length. In this article, the lap lengths of bars is discussed. During the placement of steel in Reinforced concrete structure, if the required length of single bar may fall short. To get the desired design length, lapping of two bars side by side is done. An alternative to this is to provide mechanical couplers.$

Answer 2

Lap length is one of the important term in the reinforcement.

During the placement of steel in Reinforced concrete structure, if the required length of single bar may fall short. To get the desired design length, lapping of two bars side by side is done.

Lapping is usually done where minimum bending stress is encountered. In general, lap length is 50d which means 50 times the bar diameter, if both bars are of same diameter.

For flexural tension – Ld or 30d whichever is greater is considered.

For direct tension – 2Ld or 30d whichever is greater is considered.

The straight length of lapping of bars shall not be less than 15d or 20cm.

Lap length for concrete of 1:2:4 Nominal mix:

The Lapping length in tension (MS bar – mild steel bar) including anchorage value is 58d. So eliminating the anchorage value, the lap length = 58d – 2*9d = 40d. (Where 9d = hook allowance up to 25 mm and k=2)

Lap length for M20 concrete:

Columns – 45d

Beams – 60d

Slabs – 60d

This infers that if we need to lap 20 mm diameter column bars, a minimum lap of 45 * 20 = 900 mm is provided.

hope this helps you❤