Built-Up Section Inertia Calculator
Beam + top/bottom cover plates: combined I and S — strengthening math.
Two modest 140×10 plates can double an ISMB 250's stiffness. Weld for full shear flow (q = VQ/I), and remember plates must run past the point where they're no longer needed.
Formula
Built-Up Section Inertia Calculator is a free cover plate beam for structural engineers, fabricators and site engineers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Built-Up Section Inertia Calculator
Beam + top/bottom cover plates: combined I and S — strengthening math. The calculation implements I = I_beam + 2·[b·t³/12 + (b·t)·((H+t)/2)²] (Strengthening of steel structures — standard practice). Two modest 140×10 plates can double an ISMB 250's stiffness. Weld for full shear flow (q = VQ/I), and remember plates must run past the point where they're no longer needed.
How to use Built-Up Section Inertia Calculator
- 1Enter Existing beam I in cm⁴ (ISMB 250 = 5,131 cm⁴).
- 2Enter Beam overall depth in mm.
- 3Enter Plate width in mm.
- 4Enter Plate thickness in mm.
- 5Read Combined I, Stiffness gain, New S instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Built-Up Section Inertia Calculator?
- ✓Implements the standard formula — I = I_beam + 2·[b·t³/12 + (b·t)·((H+t)/2)²]
- ✓Reference cited on-page: Strengthening of steel structures — standard practice
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Built-Up Section Inertia Calculator use?+
It computes I = I_beam + 2·[b·t³/12 + (b·t)·((H+t)/2)²], per Strengthening of steel structures — standard practice. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Two modest 140×10 plates can double an ISMB 250's stiffness. Weld for full shear flow (q = VQ/I), and remember plates must run past the point where they're no longer needed.
Can I use this for real structural design?+
It implements the exact textbook/code formula cited below the result and is ideal for sizing, checking and learning. Final designs should be verified by a qualified engineer against the full code with all load cases.
Is the Built-Up Section Inertia Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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