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 = 160 mm and height h = 200 mm. Find its second moment of area Ibase about the axis along its bottom edge.
A 150 mm × 150 mm plate has a circular hole of diameter 30 mm on its vertical centre line, with its centre 105 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the centroid.
A symmetric I-section has flanges 150 mm wide and 16 mm thick, an overall depth of 460 mm and a web 10 mm thick. Find its second moment of area Ix about the horizontal centroidal axis x.
The T-section is used as a beam with the flange on top and carries a sagging bending moment of 5 kN·m. Find the bending stress σbottom at the bottom edge.
A symmetric I-section has flanges 180 mm wide and 14 mm thick, an overall depth of 460 mm and a web 10 mm thick. It carries a bending moment of 80 kN·m about the axis x. Find the size of the bending stress σj at the junction of the web and the top flange.
Answer key
- 1. ȳ = 90.37 mm
- 2. Ibase = 426.7 × 10⁶ mm⁴
- 3. Ix = 41.49 × 10⁶ mm⁴
- 4. Ix = 302 × 10⁶ mm⁴
- 5. σbottom = 49.46 MPa
- 6. σj = 54.36 MPa
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