A beam of rectangular section (12cm wide × 20cm deep) is simply suppo...
The cross-section of beam,
Moment of inertia of cross-section
= 8 x 103cm4
Maximum moment under given loading,
Maximum bending stress
= 300 MPa
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A beam of rectangular section (12cm wide × 20cm deep) is simply suppo...
To determine the maximum bending stress induced in the beam, we can use the formula for the bending stress:
σ = (M * c) / I
Where:
σ is the bending stress
M is the bending moment
c is the distance from the neutral axis to the point of interest
I is the second moment of area (also known as the moment of inertia)
First, let's calculate the bending moment at the mid span of the beam. Since the beam is simply supported, the bending moment at the mid span can be calculated as half of the concentrated load multiplied by the span:
M = (80 kN * 12m) / 2 = 480 kNm
Next, we need to determine the distance from the neutral axis to the point of interest. In a rectangular section, the neutral axis is located at the centroid, which is half the depth of the section. Therefore, c = 20cm / 2 = 10cm = 0.1m.
Now, we need to calculate the second moment of area. For a rectangular section, the second moment of area about the horizontal axis is given by the formula:
I = (b * h^3) / 12
Where:
b is the width of the section
h is the depth of the section
Plugging in the values, we get:
I = (12cm * (20cm)^3) / 12 = 3200 cm^4 = 0.00032 m^4
Finally, we can substitute the values into the bending stress formula:
σ = (480 kNm * 0.1m) / 0.00032 m^4 = 150 MPa
Therefore, the maximum bending stress induced in the beam is 150 MPa.
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