The cutting length of the diamond stirrup is done by using simple and easy formula. The Rings or commonly called ties are used, to avoid the lateral deformation of the reinforcement when we are pouring the concrete in columns. The ties also use in the column to hold the longitudinal reinforcement in its position when the column is in under construction. The longitudinal bars in the column may change their position or alignment when we pour concrete and use a vibrator.
Let’s solve this example for your better understanding.
Example:
Suppose we are using a diamond stirrup in a column and a column having a length 550 mm and having a width 450 mm(X-section). The clear cover in the column will be 40 mm and the stirrup bar is going to use is 10 mm.
1- Calculate the cutting length of the diamond stirrup?
2- Calculate the cutting length weight of the diamond stirrup?
Given Data:
Length of column= 550 mm
Width of column= 450 mm
Clear cover= 450 mm
Stirrup bar diameter = 10 mm
Length o the stirrup=?
Weight of the stirrup=?
Solution:
The calculation of the diamond stirrup to be done in 2 steps.in the first step we calculate the hypotenuse length of the right angle by using Pythagoras theorem.in the second step, we put these values in our formula to get the final result.
Calculate the length of Hypotenuse
Hypotenuse =√ (Base Length)²+ (Perpendicular length)²
Base Length
= {Length – 2(Clear cover) – 2(Half of diameter of bar)}/2
= (550 – 2(40) – 2(5)/2
= 460/2 = 230 mm
Perpendicular length
= (width – 2(clear cover) – 2(Half of diameter of bar)}/2
= {450- 2(40) -2(5)}/2
= 360/2 = 180 mm
So putting the value of base and perpendicular in our Pythagoras theorem we can calculate hypotenuses.
Hypotenuses = √(230)² – (180)²
√52900 + 32400
= √85300
= 292 mm
Cutting length of diamond stirrup
Cutting length:
= (4 x H) + 2(10d) – 3(2d)
Where
H = Length of the Hypotenuse which we calculate in our first step
10d = Length of the Hook and d is a diameter of the bar
2d = 90*bands
3d = 135*bands
By putting the given data values and hypotenuse value (which we calculate in our first step) in our formula we get the length of our stirrup.
By putting the values
Cutting Length:
(4*292) + (200) – (60)- (60)
= (1196) – (200)- (60) – (60)
= (1396)- (120)
= 1248 mm or 1.248 m
Weight of the stirrup:
To calculate the weight of the stirrup we use a common formula
= (D²/162.2) X Length
= (10 x 10)/162.2 x 1.248
= 0.616522 x 1.276
= 0.77 kg or 770 gram
So the length of the diamond stirrup in the column will be 1.248 meters, including all two hook’s and the weight of the stirrup will be 770 grams if you are using 10 mm bar.
Note:
The length of the bar is not 100% accurate as compared to the actual length of the diamond stirrup at the side but it is approx..+ or –
