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Corner stresses of 450 x 750 column (150 kN)

Short answer

Compute stresses by superimposing direct stress (P/A = 0.444 N/mm²) and bending stresses from eccentricities in both axes. Corner stresses: A = 0.889 N/mm², B = 0.533 N/mm², C = 0.356 N/mm², D = 0.000 N/mm² (compression).

A column section 450 mm ×\times 750 mm carries a load of 150 kN acting with eccentricity of 50 mm along the 750 mm side and 45 mm along the 450 mm side from the centroid. Calculate the stress intensities at all four corners.

Data

Section 450 mm ×\times 750 mm, P=150P=150 kN. The eccentricity of the load from the centroid is 50 mm along the 750 mm side and 45 mm along the 450 mm side.

Eccentricities

e1=45 mm (across the 450 mm side)e2=50 mm (along the 750 mm side)\begin{aligned} e_{1} &= 45\ \text{mm (across the 450 mm side)}\\ e_{2} &= 50\ \text{mm (along the 750 mm side)} \end{aligned}

Section properties

A=450×750=337500 mm2Z1=750×45026=25312500 mm3Z2=450×75026=42187500 mm3\begin{aligned} A &= 450\times750 = 337500\ \text{mm}^2\\ Z_1 &= \frac{750\times450^2}{6} = 25312500\ \text{mm}^3\\ Z_2 &= \frac{450\times750^2}{6} = 42187500\ \text{mm}^3 \end{aligned}

Stresses

σ0=PA=150×103337500=0.4444 N/mm2σb1=Pe1Z1=150×103×4525312500=0.2667 N/mm2σb2=Pe2Z2=150×103×5042187500=0.1778 N/mm2\begin{aligned} \sigma_0 &= \frac{P}{A} = \frac{150\times10^3}{337500} = 0.4444\ \text{N/mm}^2\\ \sigma_{b1} &= \frac{Pe_1}{Z_1} = \frac{150\times10^3\times45}{25312500} = 0.2667\ \text{N/mm}^2\\ \sigma_{b2} &= \frac{Pe_2}{Z_2} = \frac{150\times10^3\times50}{42187500} = 0.1778\ \text{N/mm}^2 \end{aligned}

Corner stresses σ=σ0±σb1±σb2\sigma=\sigma_0\pm\sigma_{b1}\pm\sigma_{b2} (positive = compression, N/mm²):

CornerPositionWorkingStress
Atoward the load in both directions0.4444+0.2667+0.17780.4444 + 0.2667 + 0.17780.8889
Btoward the load across the 450 side, away from it along the 750 side0.4444+0.2667−0.17780.4444 + 0.2667 - 0.17780.5333
Caway from the load across the 450 side, toward it along the 750 side0.4444−0.2667+0.17780.4444 - 0.2667 + 0.17780.3556
Daway from the load in both directions0.4444−0.2667−0.17780.4444 - 0.2667 - 0.17780.0000

Check: σ0\sigma_0 = average of the four corners = 0.4444. Corner D has zero stress because the load lies exactly on the edge of the kernel (6e1/450+6e2/750=0.6+0.4=1.0006e_1/450+6e_2/750 = 0.6+0.4 = 1.000), so no tension develops.

Answer: A = 0.889, B = 0.533, C = 0.356, D = 0.000 N/mm² (compression positive); maximum 0.889 N/mm² at A.

✓ Answer checked by Claude Opus 5.5 (high effort)

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