Free Steel Tension Member Calculator — AISC 360
Design steel tension members — W-shapes, WT sections, double angles, single angles, HSS, rods, and plates. The calculator checks yielding on gross area, rupture on net effective area, block shear, and slenderness limits per AISC 360-22 Chapter D, AS 4100 Section 7, EN 1993-1-1 Section 6.2, and CSA S16 Section 13.
Typical applications: bracing members, truss chords and diagonals, hangers, tie-downs, and tension-only lateral systems.
How to Use
- Select member type: W-shape, WT, double angle, HSS, rod, or plate.
- Enter member section properties: Ag, An, bolt hole details.
- Designate connection configuration: bolted end connection with bolt layout.
- Specify steel grade: Fy and Fu values.
- Apply factored tension demand (Pu).
- Review all limit states: yielding, rupture, block shear, slenderness.
Design Checks
| Limit State | AISC 360 | AS 4100 | EN 1993-1-1 | CSA S16 |
|---|---|---|---|---|
| Yielding (gross section) | D2 (phi=0.90) | Cl 7.1 (phi=0.90) | Cl 6.2.3 (gamma_M0=1.0) | Cl 13.2(a) (phi=0.90) |
| Rupture (net section) | D3 (phi=0.75) | Cl 7.2 (phi=0.80) | Cl 6.2.3 (gamma_M2=1.25) | Cl 13.2(b) (phi=0.85) |
| Block shear | D5 (J4.3) | Cl 9.2.2 | Cl 3.10.2 | Cl 13.11 |
| Slenderness | D1 (L/r ≤ 300) | Cl 7.4 (L/r ≤ 300) | Cl 6.2 | Cl 10.2 (Le/r ≤ 300) |
| Shear lag | D3 (U factor) | Cl 7.3 | Cl 3.10.3 | Cl 13.10 |
Step-by-Step Example
Problem: Check a double-angle tension member, 2L4x4x3/8 (A36), connected to a 3/8-inch gusset plate with (4) 3/4-inch diameter bolts in one line. Pu = 200 kips.
Step 1 — Gross area yielding (AISC D2): Ag = 2 * 2.86 = 5.72 in^2 phi*Pn = 0.90 _ 36 _ 5.72 = 185.3 kips < 200 kips. Fails yielding check.
Try 2L5x5x1/2: Ag = 2 * 4.75 = 9.50 in^2 phi*Pn = 0.90 _ 36 _ 9.50 = 307.8 kips > 200 kips OK
Step 2 — Net section rupture (AISC D3): An = Ag - 2 _ (3/4 + 1/8) _ 1/2 = 9.50 - 0.875 = 8.625 in^2 U = 1 - x̅/L = 1 - 1.37/8.0 = 0.83 Ae = U _ An = 0.83 _ 8.625 = 7.16 in^2 phi*Pn = 0.75 * 58 * 7.16 = 311.5 kips > 200 kips OK
Step 3 — Block shear (AISC J4.3): Calculate along bolt hole pattern and check against 200 kips demand.
Result: 2L5x5x1/2 (A36) passes. Tension yielding governs at utilization = 200/307.8 = 0.65.
Frequently Asked Questions
What is the difference between gross section yielding and net section rupture? Gross section yielding (phi=0.90) checks the full cross-section against yield stress (Fy). Net section rupture (phi=0.75) checks the reduced section at bolt holes against ultimate stress (Fu). Yielding is a serviceability limit state (excessive elongation), while rupture is a strength limit state (fracture). Ductile design requires yielding to govern over rupture.
What is shear lag and how does the U factor work? Shear lag occurs when tension forces are transferred through only some elements of a cross-section (e.g., only the connected leg of an angle). The U factor reduces the net area to an effective net area. For bolted connections, U = 1 - (x̅/L), where x̅ is the connection eccentricity and L is the connection length. AISC 360 Table D3.1 provides U values for standard connections.
What are slenderness limits for tension members? AISC 360-22 Section D1 recommends L/r ≤ 300 for tension members subject to stress reversal (wind, seismic, vibration) to prevent excessive sag and vibration. For static tension members with no stress reversal, there is no slenderness limit, though architectural and practical considerations usually keep L/r under 400.
Which design standards cover tension member design? AISC 360-22 Chapter D in the US, AS 4100 Section 7 in Australia, EN 1993-1-1 Section 6.2 in Europe, and CSA S16 Section 13 in Canada. All standards check yielding (gross section) and rupture (net section) with slightly different resistance factors.
Is this tension member calculator free? Yes, completely free with unlimited calculations.
Disclaimer (educational use only)
This page is provided for general technical information and educational use only. It does not constitute professional engineering advice. All structural designs must be verified by a licensed Professional Engineer (PE) or Structural Engineer (SE). The site operator disclaims liability for any loss or damage arising from the use of this page.