LRFD and ASD, both
Switch design format without switching skill. Both LRFD combinations of dead and live load are evaluated, and the governing one is named.
SKL-000123 · Skill
AISC 360-22ASCE 7-22Design a steel column to AISC 360-22
Describe the column height, end conditions, bracing, section (W, HP, M or S), steel grade and loads, and pick LRFD or ASD. Mia checks flexural, torsional and local buckling in compression, or yielding and net-section rupture in tension, flexure about both axes and the H1 interaction, and names the governing check.
Mia guides you step by stepShe guides you through the inputs and explains the results.
Worked example
W 14x99 · 14 ft · Pr 360 kip + Mrx 250 + Mry 80 kip-ft · LRFD
Design verified: H1-1a interaction governs- System
- Pinned–pinned column, K = 1.0
- Section
- W 14x99 · A992 (Fy = 50 ksi)
- Height
- 14.0 ft, unbraced (Lb = 14.0 ft)
- Required strengths
- Pr = 360 kip · Mrx = 250 kip-ft · Mry = 80 kip-ft
- Design format
- LRFD
Check an A992 W14x99 column, 14 ft tall, pinned at both ends and unbraced over its height, for Pr = 360 kip, Mrx = 250 kip-ft and Mry = 80 kip-ft from a second-order analysis, per AISC 360-22 by LRFD. Check compression, flexure about both axes and the H1 interaction.
Key results
- Available compressive strength phi_c Pn
- 1128 kip (E3, y-y buckling)
- Available flexural strength phi_b Mnx
- 642 kip-ft (F2-2, Cb = 1.0)
- Available flexural strength phi_b Mny
- 311 kip-ft (F6-2, noncompact flange)
- Governing utilization
- 0.894 (H1-1a)
All values are deterministic for the stated inputs and reproduced by the skill's calculation code. AISC Design Example H.2 (V16.0) lists phi_c Pn = 1,130 kip, phi_b Mnx = 642 kip-ft and phi_b Mny = 311 kip-ft for the same member; H.2 itself applies the more conservative H2-1 and reaches 0.966.
- — The required strengths come from a second-order analysis, as the prompt states; no B1 amplification is added.
- — Cb = 1.0, conservative without a moment diagram; with equal end moments in reverse curvature F1-1 would give more.
- — E4 does not apply because the torsional unbraced length equals the weak-axis one.
- — The W14x99 flange is noncompact for flexure at Fy = 50 ksi (bf/2t_f = 9.34 > 9.15), so F3-1 and F6-2 reduce Mn.
Required inputs
- Column height, end conditions and bracing
- Section (W, HP, M or S) and steel grade
- Compression or tension; for tension the bolted end connection
- Dead and live loads with an optional uniform lateral load (D, L, wind), or required strengths already combined
- Design format (LRFD or ASD)
What you receive
- Governing check and utilization
- Available compressive strength and the buckling mode that produced it
- Available tensile strength, yielding or net-section rupture, with An, U and Ae
- Available flexural strength about both axes and the limit state behind it
- H1 interaction with the governing equation
- Assumptions and clause references
Start from an input template
These templates prefill the form with typical inputs. They are not calculated results; the calculation runs in CALC.
Prepare your calculation
Configure your column
System sketch
L = 14 ft
ft
ft
ft
ft
All required fields completed
All required fields completed
All required fields completed
kip
kip
kip-ft
kip-ft
kip-ft
kip-ft
kip/ft
kip/ft
kip/ft
kip
kip-ft
kip-ft
All required fields completed
ft
All required fields completed
Inputs completeReady to calculate
What this skill checks
Every compression limit state
Flexural buckling about both axes per E3, torsional buckling per E4 when the torsional unbraced length governs, and the effective area of slender elements per E7.
Axial tension per Chapter D
Tensile yielding of the gross section and rupture of the net section, with the shear lag factor U from Table D3.1 and the net area of the bolt holes per B4.3.
Flexure about both axes
Yielding, lateral-torsional buckling and flange local buckling per F2 and F3, minor-axis bending per F6, including the noncompact flanges of W14x90, W14x99 and HP12x74.
H1 interaction
Equations H1-1a and H1-1b for axial compression or tension with biaxial bending, with the H1.2 increase of C_b under tension and the governing equation and combination named.
Normative basis
Standards & references
The checks follow these standards. Nationally determined parameters come from the National Annex selected in the form.
AISC 360-22
CurrentANSI/AISC 360-22 Specification for Structural Steel Buildings
Edition used: ANSI/AISC 360-22 (August 1, 2022)
- §B4
- Chapter D
- Chapter E
- Chapter F
- §G2
- §H1
- Table J3.3
- Appendix 8
Status checked on
ASCE 7-22
CurrentASCE/SEI 7-22 Minimum Design Loads and Associated Criteria for Buildings and Other Structures
Edition used: ASCE/SEI 7-22 (December 2021)
- §2.3.1
- §2.4.1
Status checked on
Frequently asked questions
Frequently asked questions
VerificationDoes the skill use LRFD or ASD?
Whichever you pick. The design method is always part of the parameter form, so it is confirmed rather than assumed, and the answer names the format beside every strength.
VerificationIs torsional buckling checked?
Yes, per Section E4 whenever the torsional unbraced length exceeds the weak-axis unbraced length. Below that, E4 does not apply to doubly symmetric I-shapes, and the answer says so.
VerificationCan it check a column or hanger in tension?
Yes. Mia checks tensile yielding of the gross section and tensile rupture of the net section per Chapter D, with the net area of the bolt holes and the shear lag factor U from Table D3.1, and combines tension with bending per H1.2. Block shear and the bolts themselves belong to the connection design.
VerificationWhat happens with slender W-shapes such as W14x43?
The skill classifies flange and web per Table B4.1a and, for a slender element, computes the effective area per Section E7 at the governing buckling stress.
VerificationAre second-order effects included?
Forces are used as entered and the answer says so. For a braced column the skill offers the B1 amplification of Appendix 8 as a follow-up; sway effects (B2) need a frame analysis.
Ready for your first check?
Start with the example and adapt it to your structural system.
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