# Cutting length of spiral ring ?

The cutting length of spiral ring is very simple and easy. The spiral ring is used in the binding of pile inner bar that is used is called master rings which are similar to circular stirrups, but we are not provided with a hook in this ring, but outside we have a spiral ring to bind the pile which is called spiral bars.

Let’s solve this example.

**Example:**

We have a length of the pile which is 20m and the pitch or spacing for the spiral bar is 200mm and dia of the pile is 1m and the dia of the spiral bar is 8mm, assume the clear cover is 50mm in this case?

**Given data :**

Dia of pile = 1000mm or 1m

Pitch or spacing of spiral bar = 200mm

Length of pile = 20m

Dia of spiral bar = 8mm

Clear cover = 50mm

**Solution:**

1st we find the radius of the spiral and then the length of the spiral ring which completes the one pitch in which distance is given in the data,

2nd find out the no of spirals and then how many no laps are required in the total length of the spirals.

**1: Radius of spiral ring**

= Radius of the pile (d2) – clear cover – half of spiral dia bar

= 500 – 50 – 4

= **446 mm so** the length of 1 no of the spiral ring is

= 2 x 3.14 x r

= 2 x 3.14 x 446

= **2800 mm or 2.8m Ans.**

**2: No spiral **

no of spirals

= length / spacing of pitch + 1

= 20000 / 200 + 1

= 100 + 1

= **101 nos**

101 nos of pitches are completed for a spiral bar in this length of the given pile.

So total length of the spiral bar is

total length

= no of pitches x radius of the pile

= 101 x 2.8m

= **282.8m**

** **

**Laps **

We know that length of one full bar is 12m so lapping is required in this case.

no of laps = total length of spirals – 1 / length of one bar

= 282.8 – 1 / 12

= 23.56 – 1

= **22.56 say 23 nos**

23 nos 0f laps are required

Lap considered = 50d

< where d is dia of bar>

= 50 x 8

= 400mm or 0.4m

**Total length of spiral bar**

Total length of laps

= 23 x 0.4

= **9.2m**

Total length of spiral rings

= 282.8 + 9.2

= **292m**

**Weight:**

= d^{2}/162 x length

= 8 x 8 / 162 x 292m

= **115.35 kg Answer…**