# Length calculation of Spiral Bar or Helix Bar This civil engineering video tutorial shows you how to determine the length of spiral bar or helix bar.

The spiral bar is also called transverse reinforcement. It is mostly used in strengthening circular column. In beam, this type of transverse reinforcement is known as stirrups.

For rectangular column, it is called ties whereas in circular column, it is called spiral reinforcement or spiral bar.

The purpose of this type of reinforcement is to retain the main bars in exact position.

The height or depth of the column is taken as 10 feet.

The gaping among each spiral is 2 feet. The gaping gapping among two successive spiral is known as pitch.

To determine the length, the following formula is used:

L = n√C2 + P2; here n denotes number of turns in the spiral bar, C denotes circumference of the bar and P denotes pitch of the bar.

The value of n is determined with the following formula :-

n = H / P = Total Height of the column / Pitch = 10 / 2 = 5

So, there are 5 number of turns in this spiral column or bar.

The value of C is determined with the following formula :-

C = πD = 3.14 x 3 (value of pie = 3.14, diameter is taken as = 3 feet) = 9.4 feet

The value of pitch is given as 2 feet.

After putting the above value in the formula, we get the following result:

L = n√C2 + P2 = 5√9.42 + 22 = 5√92.73 = 48 feet

So, the length of the spiral bar is 48 feet.

### Read More: Bar Bending Schedule for footings / Computation of Steel reinforcement in footings

To get more details, go through the following video tutorial.

Video Source: Civil Engineering