Worked Examples

Example 1: Selecting a Structural Shape Family

A warehouse needs (1) a 30 ft roof beam, (2) a diagonal wall brace, and (3) a heavily loaded multi-story column. Identify reasonable starting shape families.

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Example 2: LRFD and ASD Are Different Required-Strength Formats

A floor girder has service dead-load moment MD=15 kip-ftM_D=15\text{ kip-ft} and service live-load moment ML=30 kip-ftM_L=30\text{ kip-ft}. For this example, the adopted strength combination is 1.2D+1.6L1.2D+1.6L and the adopted ASD combination is D+LD+L.

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Example 3: Why the Code Edition Must Be Written Down

A class calculation begins with NSCP 2015 project context. A student then copies a later ASCE load combination from an online source without identifying the edition.

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Example 4: Carbon Equivalent Interpretation

A steel chemistry is evaluated using the IIW-style expression

CE=C+Mn6+Cr+Mo+V5+Ni+Cu15.CE=C+\frac{Mn}{6}+\frac{Cr+Mo+V}{5}+\frac{Ni+Cu}{15}.

Use C=0.18C=0.18, Mn=0.90Mn=0.90, Cr=0.05Cr=0.05, Mo=0.02Mo=0.02, V=0.01V=0.01, Ni=0.04Ni=0.04, and Cu=0.15Cu=0.15 percent.

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Example 5: Thermal Movement

A 120 ft steel member is installed at 60∘F60^\circ F. Use α=6.5×10−6/∘F\alpha=6.5\times10^{-6}/^\circ F. Find free movement to −10∘F-10^\circ F and 110∘F110^\circ F.

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Example 6: Reading Shape Designations

Interpret W18x50, L6x4x1/2, and HSS8x6x3/8.

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Example 7: Serviceability Criterion Is a Project Input

A simply supported beam spans 24 ft and has Ix=800 in4I_x=800\text{ in}^4. Service live load is 1.2 kip/ft1.2\text{ kip/ft}. Check an explicitly selected L/360L/360 criterion.

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Key Takeaways
  • Shape-family selection is preliminary; limit states and constructability determine the final section.
  • LRFD and ASD compare different required-strength formats with different available-strength formats.
  • Code-edition traceability prevents accidental hybrid designs.
  • A carbon-equivalent calculation is not a standalone preheat decision.
  • Shape designations are shorthand; exact properties come from the applicable shape/product data.
  • Serviceability limits must be identified from the governing project/code criteria, not assumed universally.