OVERLAPPING OF STEEL BARS IN DIFFERENT CONCRETE MIX

OVERLAPPING OF STEEL BARS IN DIFFERENT CONCRETE MIX


The proper overlapping of steel bars in different concrete mix is very important because in R.C.C construction works proper lapping of steel bars is very essential.
Before going to calculate the lapping of the steel lets clear the following basic concepts.
Why over Lapping of steel is important?
The over lapping of the steel is very important in R.C.C works because splicing of steel is used to transfer all the stresses from one bar to another bar. The length of the lapping is different in different concrete mixes because different concrete having a different crushing strength.
At the site basically we receive a steel bar at the site having a length 6 to 12 meter. So if we have a length more then 12 m. We must over lap the steel bar so the splice length of the steel bar depend on the,
  1. Diameter of the steel bar going to use.
  2. Amount of Stresses developed in the bars.
  3. And what type of concrete is going to use. (M15, M20 etc.)
Suppose we have a column having a height 200 ft. So at the side we don’t have a 200 ft long one single bar we must over lap the bar to achieve the total length of the column.

OVER LAPPING RESTRICTION:

  1. The lapping is not provided above 36 mm diameter bars because those diameter bars doesn’t transfer the stresses form one bar to another bar and also the alignment of the column bar is also affect by providing the lap on these bar.
  2. The lapping of the steel bars also not provided in high shear force zones and it should provided at that zone where shear force will be minimum.

LAPPING OF DIFFERENT CONCRETE MIX:

Basically we have three type of zone Compression zone Neutral zone and Tension zone. In different zones we provide different splice length of the steel bars. In R.C.C construction we mainly use 3 type of concrete mix M15, M20, and M25.

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