Find the height ȳ of the centroid of the T-section above its bottom edge.
Centroid & second moment of area worksheet with answers
A rectangular section has width b = 300 mm and height h = 325 mm. Find its second moment of area Ibase about the axis along its bottom edge.
A 100 mm × 240 mm plate has a circular hole of diameter 60 mm on its vertical centre line, with its centre 84 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the centroid.
A 120 mm × 150 mm plate has a circular hole of diameter 40 mm on its vertical centre line, with its centre 60 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the centroid.
A 200 mm × 150 mm plate has a rectangular cut-out 30 mm wide and 30 mm high, centred on the vertical centre line with its centre 90 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the centroid.
The T-section is used as a beam with the flange on top and carries a sagging bending moment of 15 kN·m. Find the bending stress σbottom at the bottom edge.
Answer key
- 1. ȳ = 98.75 mm
- 2. Ibase = 3433 × 10⁶ mm⁴
- 3. Ix = 110.4 × 10⁶ mm⁴
- 4. Ix = 33.32 × 10⁶ mm⁴
- 5. Ix = 55.97 × 10⁶ mm⁴
- 6. σbottom = 68.66 MPa
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