To determine the Diameter, Unit Weight, and Bending of the Steel bar.
INTRODUCTION:
One of the most important tests in engineering technology is to determine the Diameter, Unit Weight, and Bending of the Steel bar.
One of the most important tests in engineering technology is to determine the Diameter, Unit Weight, and Bending of the Steel bar.
Apparatus Required:
UTM, test specimen, bending table support pin.
- Take a test specimen of the steel rod.
- Measure the diameter of the steel rod. Take at least 3 readings and
calculate the mean. - Now place the test specimen in the bending table specimen should be kept
in the bending table in such a way that the plane - Intersecting the longitudinal ribs is parallel to the axis of the pin.
- Select a suitable range of scale.
- Start the machine and start applying load continuously and uniformly
throughout the bending. - As the load is applied to the rod, it will start bending.
- Discontinue the application of load when the angle of bent specified in the material specimen has been achieved before rebound.
- Take out the specimen and examine the tension surface of the specimen for cracking.
Specification for Angel in Bend Test:
Bar # 3 to Bar #11 should bend up to 1800 without a crack
Bar # 14 & Bar #18 should bend upto900 without crack
This all specification has been given in AASHTO (American Association for State Highway and Transportation Officials)
Bend Test Requirements:
Unit Weight of steel bar:
After estimating it is very important to know the unit weight of steel bars
because, we estimate it as 100 meters 20mm Ø bar or 100 feet 16mm bar, etc. (ø is the symbol of diameter).
But steel bar suppliers will not understand this notation, they measure the steel bars in weight. Therefore, we have to order them in kg, quintal, or ton. In this article, we will discuss how to calculate the unit weight of steel bars of different diameters.
The formula is W = D^2 L/162.2
Where
W = Weight of steel bars.
D= Diameter of steel bars in mm.
L = Length of bars in meters.
Example 1: Calculate the weight of 60 meters long 12 mm ø bar.
Here, D = 12 mm.
L= 60 m.
We know that, W = D2L/162
W = 122 x 60/162=53 kg
Weight of 60 m 12mm Ø bar is 53 kg.
Let us look for another example.
Example 2: Calculate the weight of 100 m 16 mm Ø bar.
Here, D= 16 mm.
L = 100 m.
W = 162 x 100/162 = 158 kg.
If we put a 1-meter length for each diameter of steel bar in the formula then we will get the unit weight.
.
10mm Ø bar = 102 x 1/162 = 0.617 kg/m
12mm ø bar = 122 x 1/162 = 0.888 kg/m
16mm o bar 16’x 1/162-1.580 kg/m 20mm bar 20x 1/162-2.469 kg/m
If we multiply the length of the bars by this unit weight, we will get the total weight of the steel bars.
For example, the total weight of a 1000-meter long 20mm steel bar is
1000 x 2.469-2469 kg
Using the same method, we can calculate the unit weight of different steel bars.
Here I have calculated in meter but we can also calculate in foot. To calculate in foot we have to use the following formula:
W= D’L/533
Where D Diameter of bars in mm.
L-Length of bars in foot
We know a formula to calculate the weight of the bar. That is D’L/162
Where,
D- Diameter of bar in millimeters
L Length of bar in meter
Now the question is what the 162 is
Let us see
To calculate the weight of something else we often use the following formula. To calculate the weight of reinforcement same formula can be used
Weight volume x unit weight (volume-area x length]
So,
Weight-area x length (L) x unit weight (v) [area-D
Therefore,
Weight (W)= RD/4 x L x 7850
We know the unit weight of the rod is 7850 kg/m3
However, there are two conflicting units in the above formula. That D is in millimeters (as we get the rod as millimeters, such as 16mmø, 20mmø, etc.) and the unit weight of the rod is in m’ (kg/m3). If we estimate the rod in meters then L also is in meter units in the above formula.
Therefore, if we do not convert all three units as the same unit we cannot use the above formula. We have to convert either D from millimeter to meter or L and y from meter to millimeter.
Let us convert the D from millimeter to meter.
1 mm 1/1000 meter
So,
D2 (mm) D/(1000 x 1000), meter
If we implement this in the above formula, we will find
W= D2/(4x (1000 x 1000)) x L x 7850
D’L/162
Keep in mind that, in this formula, D always should be in millimeters and L always should be in meters.
Diameter of steel bar:
The formula is D=
Where
Wx162
W Weight of steel bars.
D Diameter of steel bars in mm.
L Length of bars in meters.
Example 1: Calculate the Diameter of 60 meters long and 53 kg weight steel rod.
Here, W = 53kg.
L= 60 m.
Wx162
We know that, D=
L
53×162
D =
= 12mm
60
The diameter of 60 m long and 53 kg weight steel bar is 12mm.
Results:
Bending of steel bar = Unit weight of steel bar= Diameter of steel bar=
Review questions:
- What is the bending of a steel bar?
- What do you mean by the unit weight of the steel bar?
- How do you calculate the diameter of a steel bar?
