In this article, we will cover how to calculate the cut length of the spiral stirrups in this topic. We know about the helical stirrups used in circular piles and columns. Another term for the stirrups is also called ring or shear reinforcement.
the main reinforcement in RCC structure like column
and beam will behold in this closed loop of reinforcements. The spiral helical
ring used in the column provides lateral support to the main bar against the
buckling, which is applied to the beam and column at right intervals.
Also, they protect the RCC structure from collapsing
during a seismic activity like an earthquake. It is used to resist lateral shear
stress and diagonal tension stress in RCC structure and provide stability to
the reinforcement of Steel bar. let us discuss how to calculate the cutting
length of spiral stirrups.
Let's consider as,
GIVEN DATA
The diameter of pile or column
= 600mm or 0.6m
Radius of pile or column = 300mm or 0.3m
Spacing or Pitch of spiral
bar = 200mm
Length of pile = 10m
Dia of spiral bar = 8mm
Clear cover = 50mm
SOLUTION:
STEP: 1
we
find the radius of the spiral and then the length of the spiral ring which
completes the one spacing of spiral bar which distance is given in the data,
RADIUS OF SPIRAL RING
= Radius of pile (d/2) –
clear cover – half of spiral dia bar
= 300 – 50 – 4
= 246 mm
So the length of 1 no of the spiral ring is
= 2Ï€r =
2 x 3.14 x r
= 2 x 3.14 x 246
= 1544.88 mm or 1.5m
STEP: 2
Find
the number of spirals, then find out how many laps are needed in the total
length of the spirals
NUMBER OF SPIRAL
Number of spirals = length
/ spacing of spiral+ 1
= 10000 / 200 + 1
= 50 + 1
= 51 nos
51 nos of the spiral are completed for spiral bar in this length of given column or pile.
So, Total Length of the spiral bar is
Total Length = No Of Spiral
x Radius Of The Pile
= 51 x 1.5m
= 76.5 meters
We know that the length of a whole bar
is 12m, so lapping is necessary in this case.
No of laps
= total length of spirals/length of one bar
= 76.5 / 12
= 6.29 say
7 nos
7 nos of laps are required
In general, lap length is
50d which means 50 times the bar diameter
where d is dia of bar
= 50 x 8 = 400mm or 0.4m
Total length of spiral bar
Total length of laps = 7 x 0.4 = 2.8m
Total length of spiral rings = 76.5 + 2.8 = 79.3m
Total weight of spiral rings
= d2/162 x length
= 8^{2} / 162 x 79.3m = 31.32 kg
.
Also
Read: All
You Want To Know About Stirrups In Beam And Column
Also
Read: How
to Calculate Cutting Length For Square Stirrups
Also
Read: How
to Calculate Cutting Length Of Circle Stirrups In Beam And Column
Also
Read: How
to Calculate Cutting Length Of Triangle Stirrups

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