Combined Stresses — Worked Examples

Every combined-stress calculation is point-specific. Resolve load effects at the section, compute compatible stress components at the same point, then superimpose or transform them as required.

1. Concentric Compression

A short column with area 60000 mm260000\text{ mm}^2 carries a concentric compressive force of 180 kN180\text{ kN}. Determine the normal stress using tension-positive signs.

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2. Eccentric Compression at the Middle-Third Boundary

A 200 mm×300 mm200\text{ mm}\times300\text{ mm} rectangular column carries 150 kN150\text{ kN} compression with eccentricity e=50 mme=50\text{ mm} along the 300 mm300\text{ mm} depth. Determine the edge stresses.

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3. Eccentricity Inside the Kern

Use the same column and load as Example 2, but with e=30 mme=30\text{ mm}. Determine the edge stresses.

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4. Eccentricity Beyond the Kern

Use the same 200 mm×300 mm200\text{ mm}\times300\text{ mm} column and 150 kN150\text{ kN} load, but take e=75 mme=75\text{ mm}. Evaluate the linear full-contact edge stresses.

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5. Axial Tension plus Bending

A 100 mm×200 mm100\text{ mm}\times200\text{ mm} rectangular member carries 100 kN100\text{ kN} axial tension and a bending moment of 6.0 kN⋅m6.0\text{ kN}\cdot\text{m} about the strong centroidal axis. Determine the extreme normal stresses.

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6. Middle-Third Limit for a Wall Base

A rectangular wall base is 1.20 m1.20\text{ m} wide in the direction of eccentricity. What is the maximum eccentricity that preserves full compression under the elementary middle-third rule?

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7. Eccentricity from Force and Moment

A compression resultant is P=300 kNP=300\text{ kN} and the same load system produces M=60 kN⋅mM=60\text{ kN}\cdot\text{m} about the section centroid. Determine the equivalent eccentricity. If the section depth is 1.50 m1.50\text{ m}, is it inside the middle third?

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8. Principal Stresses from Combined Normal and Shear Stress

At a point in a beam, σx=60 MPa\sigma_x=60\text{ MPa}, σy=0\sigma_y=0, and τxy=30 MPa\tau_{xy}=30\text{ MPa}. Determine the principal stresses.

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9. Extreme Fiber of a Beam under Transverse Loading

At the extreme top fiber of an elementary beam section, the bending stress is −80 MPa-80\text{ MPa}. What transverse shear stress does the elementary free-surface model give there, and what are the in-plane principal stresses?

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10. Neutral-Axis Shift under Eccentric Compression

For the 200 mm×300 mm200\text{ mm}\times300\text{ mm} column carrying 150 kN150\text{ kN} at e=75 mme=75\text{ mm}, locate the zero-normal-stress line measured from the centroid using the linear full-contact model.

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11. Point-Specific Combined-Stress Check

A rectangular beam section has its largest bending stress at the extreme fibers and its largest transverse shear stress at the neutral axis. Is it correct to add those two maxima directly and call the result the stress state at one material point?

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