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How to use the steel member calculator

Pick a section, give its length and the factored actions, and read the governing check: compression, bending with lateral-torsional buckling, shear and their interaction.

All guides Inputs Result Calc sheet Walk-through Mistakes

1. What the calculator does

The steel member calculator checks a hot-rolled steel member under axial load, bending about both axes and shear. It classifies the section, works out the compressive resistance, the bending resistance with lateral-torsional buckling, the shear resistance and the interaction of axial load and bending, and gives a material take-off for the project.

The code routes are SANS 10162-1 (limit states design of hot-rolled steelwork) and Eurocode 3 (EN 1993-1-1). The sections come from the tables on the page, including the South African range (SAISC / SANS).

Steel member calculator header with the PASS badge — The header: PASS 89 %, governed by axial and bending with lateral-torsional buckling.

2. The inputs, group by group

Input	What it means	Typical value
Member	A mark (M1...) and the design code.	M1, SANS 10162-1
Section	Standard, family and section from the tables. Type in Find to filter the list.	203×203×46 UC
Grade	Steel grade; it sets f_y. The class comes from the engine.	S355 or 350WA
Length	Effective length KL for buckling, and the LTB length (empty = KL).	KL = storey height
Actions	Factored axial N (+ compression, − tension), M_x major, M_y minor and shear V. “More load sets” adds further combinations.	N 600 kN, M_x 40 kNm, V 120 kN

Steel member inputs: member, section, grade, length and actions — The inputs. The actions here are factored (“factored, set 1”): unlike the concrete calculators, you enter design values.

3. How to read the result

“Section and resistances” lists the slenderness KL/r_min, the compressive resistance C_r, the bending resistances M_rx and M_ry, the shear resistance V_r, the section class and the governing check with its clause. The last line is the interaction utilisation: here 89 %.

Section shape and resistances table — Section and resistances. The governing check names its clause: axial + bending, (c) lateral-torsional, SANS 10162-1 13.8.3(c).

Read the governing line before changing the section. If lateral-torsional buckling governs, a restraint that shortens the LTB length can do more than a heavier section. If the class is 4 (slender), the engine reduces the resistance; a stockier section is usually the cheaper fix. Anything the engine could not check shows as NOT CHECKED; it is not a pass.

Design checks card with the sign-in note — Design checks: SANS 10162-1 · 8 pass. Signed out, the card shows the access note instead of the list of checks.

4. Calc sheet and take-off

The result (pass / fail and utilisation) stays free for everyone. Every check with its clause, the calc sheet and the bending schedule are open to signed-in users. Sign in free: 3 designs a month (one calculator, open for 24 hours). Unlimited with a calculator pack.

The N–M interaction diagram and the full detail drawings are part of the paid plan. The take-off at the bottom of the page adds each member to one material list for the project: section, grade, length, number and mass.

N-M interaction panel marked paid plan — The N–M interaction diagram is part of the paid plan.

Combined steel take-off of all members — The combined steel take-off: one member, 184.3 kg. Add members to build the list for the whole frame.

5. A 2-minute walk-through

Open the calculator. It starts with a 203×203×46 UC in S355, KL 4.0 m, N 600 kN, M_x 40 kNm and V 120 kN.
Read the badge: PASS 89 %, axial and bending with lateral-torsional buckling.
Type a shorter LTB length (say 2 m, for a restraint at mid-height) and watch the utilisation drop.
Pick a lighter section from the list and see where it fails, and on which check.
Add a second load set for the wind case with “More load sets”.
Sign in for the clause-by-clause checks and the calc sheet.

6. Common mistakes

Characteristic actions. This calculator takes factored actions; multiply by the load factors first, or use the frame results.
KL for both axes. A column braced about one axis only buckles about the other; check KL for each axis and the LTB length separately.
Wrong sign on N. Compression is positive; a tension member typed as compression is checked for buckling it will never see.
One load set only. The worst case for a column is often not the highest axial load; add the wind set.

7. Where it fits

For connections, go on to the base plate, fin plate and end plate calculators. For a whole portal frame, see Steel Design 2.

8. Learn more

Try it nowThe calculator opens with the walk-through inputs above. The result is free; sign in for the checks, calc sheet and schedule.
Open the steel member calculator

A guide to using the calculator, not a design. Check every value against the current code and your own project, and have the design checked and signed by a registered professional engineer.

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