Brace Connection Calculator: Gusset Plate, Bolts & Welds (AISC/LRFD/ASD)
Free AISC 360-22 brace connection calculator for gusset plates, bolts, welds, Whitmore, UFM, and SCBF seismic. Instant LRFD/ASD checks and reports.
Quickly design and verify steel brace connections per AISC 360-22 (LRFD & ASD) with this comprehensive, easy-to-use calculator. It handles single diagonal, X-brace, chevron, and knee braces, performing full checks for:
- Brace tension yielding/rupture and compression buckling
- Gusset plate Whitmore yielding, Thornton buckling, shear, and block shear
- Bolt shear, bearing, and tear-out
- Fillet weld strength (directional method)
- Uniform Force Method (UFM) interface forces
- Seismic SCBF provisions (2t clearance, Ry overstrength)
Live diagram, real-time results, and professional report generation make it ideal for structural engineers performing preliminary or detailed connection design. Built for accuracy and speed. For educational and preliminary use—always verify with licensed engineering judgment.
SteelSolver.com
Brace Connection Calculator
AISC 360 (LRFD/ASD) | Gusset Plate, Bolt & Weld Design | UFM Transparency | Whitmore Section | Seismic SCBF
☍ Brace Configuration
▲ Member Sections
📊 Live Connection Diagram
ⓘ Diagram updates in real time. Shows brace angle, gusset plate, Whitmore section (30° fan), and UFM force interfaces. Not to scale.
⚡ Quick-Load Presets
⚡ Brace Axial Demand
kips
kips
°
Horizontal component = P·cosθ | Vertical component = P·sinθ
ℹ
For LRFD: enter factored (Pu) loads. For ASD: enter service (Pa) loads. The tool auto-applies appropriate resistance factors.
UFM Interface Forces
$$H_b = P_u \cos\theta - \frac{\alpha}{\alpha+\beta}\cdot P_u\sin\theta$$
$$V_c = P_u \sin\theta - \frac{\beta}{\alpha+\beta}\cdot P_u\cos\theta$$
Where α, β are UFM eccentricity parameters — AISC 360-22 Commentary C-J1
📈 Load Combinations
kips
kips
Computed UFM Forces
| Hb (Beam Horiz.) | — |
| Vb (Beam Vert.) | — |
| Hc (Col. Horiz.) | — |
| Vc (Col. Vert.) | — |
▲ Gusset Plate Geometry
Whitmore Width (30° Fan)
$$L_w = L_{bolt} + 2\,L_{conn}\,\tan 30°$$
AISC 360-22 §J4.4
◯ Effective Length & KL/r
—
—
Thornton Gusset Buckling
$$r_{gp} = \frac{t_{gp}}{\sqrt{12}}, \quad \frac{KL_t}{r_{gp}} \le 25 \text{ (rec.)}$$
Thornton (1991), AISC Design Guide 29
📈 Net Area & Shear Lag
Net & Effective Areas
$$A_n = A_g - n \cdot d_h \cdot t \quad \text{(net area)}$$
$$A_e = U \cdot A_n \quad \text{(effective net area, shear lag)}$$
AISC 360-22 §D3.2, Table D3.3
🔧 Bolt Design
Bolt Properties (Per Bolt)
| Fnv | 48 ksi |
| Ab | 0.601 in² |
| φrnv | — |
| Group Capacity | — |
🔥 Weld Design
Weld Capacity
| FEXX | 70 ksi |
| Directional Factor k | — |
| φRn/L (kip/in) | — |
| Total Weld Capacity | — |
Fillet Weld Strength (Directional Method)
$$\phi R_n = \phi \cdot 0.6 F_{EXX} \cdot (0.707w) \cdot L_w \cdot (1 + 0.5\sin^{1.5}\theta_w)$$
AISC 360-22 Eq. J2-4
—
Governing Limit State
—
Max DCR
—
Overall Status
—
Connection Capacity
✅ Limit State Checks
| Limit State | Code Ref. | Demand | Capacity | DCR | Utilization | Status |
|---|---|---|---|---|---|---|
| Configure inputs and click Calculate. | ||||||
ⓘ Accuracy note: Results are based on AISC 360-22 analytical equations. For final engineering design, an independent licensed engineer should review calculations. This tool does not replace professional judgment or code-required peer review.
ƒ Brace Member Tension Checks
Tensile Yielding on Gross Area — AISC 360-22 Eq. D2-1
$$\phi_t P_n = \phi_t \cdot F_y \cdot A_g \quad (\phi_t = 0.90)$$
Tensile Rupture on Net Area — AISC 360-22 Eq. D2-2
$$\phi_t P_n = \phi_t \cdot F_u \cdot A_e \quad (\phi_t = 0.75)$$
$$A_e = U \cdot A_n, \quad A_n = A_g - \sum(d_h \cdot t)$$
Block Shear Rupture — AISC 360-22 Eq. J4-5
$$\phi R_n = \phi \bigl[0.6 F_u A_{nv} + U_{bs} F_u A_{nt}\bigr] \le \phi\bigl[0.6F_y A_{gv} + U_{bs}F_u A_{nt}\bigr]$$
$$\phi = 0.75$$
▲ Gusset Plate Checks
Whitmore Tensile Yielding — AISC 360-22 §J4.4
$$\phi R_n = \phi \cdot F_{y,gp} \cdot A_w, \quad A_w = t_{gp} \cdot L_w$$
$$L_w = L_{bolt} + 2\,L_{conn}\tan 30°$$
Thornton Gusset Compression Buckling — Thornton 1991 / AISC DG29
$$r_{gp} = \frac{t_{gp}}{\sqrt{12}}, \quad \lambda_c = \frac{KL_t}{r_{gp}\pi}\sqrt{\frac{F_{y,gp}}{E}}$$
\[\phi F_{cr} = \phi \cdot \begin{cases} (0.658^{\lambda_c^2})F_y & \lambda_c \le 1.5 \\ \frac{0.877}{\lambda_c^2}F_y & \lambda_c > 1.5 \end{cases}\]
$$\phi R_n = \phi F_{cr} \cdot A_w$$
Shear Yielding on Gusset Interface — AISC 360-22 Eq. J4-3
$$\phi R_n = \phi \cdot 0.6 F_{y,gp} \cdot A_{gv} \quad (\phi = 1.0)$$
Shear Rupture on Gusset Interface — AISC 360-22 Eq. J4-4
$$\phi R_n = \phi \cdot 0.6 F_u \cdot A_{nv} \quad (\phi = 0.75)$$
🔧 Bolt & Weld Formulas
Bolt Shear Strength — AISC 360-22 Eq. J3-1
$$\phi r_n = \phi \cdot F_{nv} \cdot A_b \quad (\phi = 0.75)$$
Bolt Bearing Strength — AISC 360-22 Eq. J3-6a
$$\phi r_n = \phi \cdot 2.4\,F_u\,d_b\,t \quad (\phi = 0.75)$$
Bolt Tear-Out (Edge Bolt) — AISC 360-22 Eq. J3-6c
$$\phi r_n = \phi \cdot 1.2\,F_u\,l_c\,t \quad l_c = e_1 - d_h/2$$
Fillet Weld Strength (Directional) — AISC 360-22 Eq. J2-4
$$k = 1 + 0.5\sin^{1.5}\theta_w$$
$$\phi R_n = \phi \cdot 0.6\,F_{EXX} \cdot 0.707\,w \cdot L_w \cdot k \quad (\phi = 0.75)$$
🌋 Compression (Brace Buckling)
Flexural Buckling — AISC 360-22 §E3
$$F_e = \frac{\pi^2 E}{(KL/r)^2} \quad \text{(Euler stress)}$$
\[\phi_c F_{cr} = \begin{cases} \phi_c(0.658^{F_y/F_e})F_y & KL/r \le 4.71\sqrt{E/F_y} \\ \phi_c \cdot 0.877 F_e & KL/r > 4.71\sqrt{E/F_y} \end{cases}\]
$$\phi_c P_n = \phi_c F_{cr} A_g \quad (\phi_c = 0.90)$$
AISC 360-22 Eqs. E3-2, E3-3
⚡ Uniform Force Method (UFM)
Force Distribution — AISC 360-22 Commentary C-J1 / AISC 15th Ed. Part 13
$$r = \sqrt{(\bar{\alpha}+e_b)^2 + (\bar{\beta}+e_c)^2}$$
$$H_b = P_u\frac{\bar{\alpha}}{r} \sin\theta, \quad V_b = P_u\frac{e_b}{r}\sin\theta$$
$$H_c = P_u\frac{e_c}{r}\cos\theta, \quad V_c = P_u\frac{\bar{\beta}}{r}\cos\theta$$
eb = beam depth/2, ec = column depth/2, α and β are work-point offsets.
🗎 Calculation Report
ℹ
This report includes all inputs, formulas, code references, and results. Copy and paste into your design package or print via browser Print (Ctrl+P).
Click "Generate Report" to create the full calculation report.
📈 Project Notes
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Brace Connection Calculator (AISC 360)
Complete User Guide
A step-by-step reference covering every input, all limit-state formulas, Whitmore section analysis, Uniform Force Method (UFM), seismic SCBF provisions, and how to interpret results—with worked examples and common-mistake microcopy.
⚙ What Is a Brace Connection Calculator?
A brace connection calculator is a structural engineering tool that designs and verifies the connection between a diagonal brace member and the surrounding beam-column frame through a gusset plate. These connections are the critical transfer point where the brace's axial force—whether tension from wind uplift or compression from gravity—is distributed into the frame through bolts, welds, and plate material.
The SteelSolver Brace Connection Calculator implements the complete AISC 360-22 analytical design procedure for steel braced frames, covering every failure mode along the load path: brace member capacity, gusset plate stress, bolt group strength, weld rupture, and combined interface forces using the Uniform Force Method (UFM).
What Design Codes Are Covered?
| Code | Scope | Supported Features |
|---|---|---|
| AISC 360-22 | Primary structural steel design standard (USA) | LRFD & ASD, Chapters D, E, J; Uniform Force Method |
| AISC 360-16 | Previous edition (2016) | Same chapters; selectable in Code Edition dropdown |
| AISC 341-16 | Seismic provisions | SCBF & OCBF, 2t ellipse clearance, Ry overstrength |
| LRFD | Load & Resistance Factor Design | φ = 0.90/0.75/1.00 per limit state |
| ASD | Allowable Strength Design | Ω = 1.67/2.00/1.50 per limit state |
Unlike simple bolt-group or weld calculators, this tool evaluates the entire connection system as a single design problem, automatically identifying which element—bolt, weld, gusset plate, or brace member—governs the design and reporting the controlling Demand-to-Capacity Ratio (DCR).
🚫 Key User Pain Points & How This Calculator Solves Them
Engineers and students working on steel braced frame connections consistently encounter the same frustrations with existing tools. Here is how the SteelSolver Brace Connection Calculator addresses each one directly.
Black-Box Outputs
✗ Most tools show a single PASS/FAIL number with no formula trail, making PE stamp sign-off nearly impossible.
✓ Every limit state shows its AISC equation reference (e.g., “Eq. D2-1”), demand, capacity, DCR, and a color-coded utilization bar so any reviewer can trace the math.
No Seismic Provisions
✗ Free calculators skip AISC 341 SCBF requirements entirely—no RyFy overstrength, no 2t ellipse gusset clearance check.
✓ Toggle SCBF or OCBF mode to activate seismic provisions including expected brace strength (RyFyAg) and the critical 2-thickness (2t) hinge clearance check per AISC 341-16 §F2.
Imperial-Only Tools
✗ Nearly every free brace connection tool forces kip/in units, excluding metric-first firms and international users.
✓ One-click unit toggle switches all inputs and outputs between Imperial (kip, in, ksi) and Metric (kN, mm, MPa) globally, with every result labeled with its unit.
No UFM Transparency
✗ Engineers cannot see the Uniform Force Method distribution (H_b, V_b, H_c, V_c), so geometry cannot be iterated intelligently.
✓ The Loads tab displays all four UFM interface forces computed in real time from your α, β, and brace angle inputs.
No Printable Report
✗ No export means engineers cannot include calculations in submittal packages or share for peer review.
✓ The Report tab generates a full hand-calc-style text report with all inputs, formulas, code references, and results. Copy to clipboard or print directly from the browser.
No Whitmore Visualization
✗ Engineers must manually sketch the Whitmore section to confirm gusset geometry is adequate—a time-consuming and error-prone step.
✓ The live SVG diagram shows the 30° Whitmore fan projection from the bolt group and updates in real time as you change the brace angle and connection geometry.
Slow Iteration
✗ Testing “what if” scenarios (changing bolt diameter, plate thickness) requires re-running a full calculation each time.
✓ Every field triggers live recalculation. Change any input and all DCR values and utilization bars update instantly—no Run button required.
No Beginner Guidance
✗ Junior engineers don’t know which check governs or what to change when something fails.
✓ Each row in the results table cites the controlling AISC equation and highlights the governing limit state in orange. This guide explains every formula in plain language.
📊 Connection Diagram & Force Flow Visual
The diagram below shows a typical single-diagonal brace connection at a beam-column corner, the most common configuration in steel braced frames. Understanding the force path from brace to gusset to beam/column is essential before entering inputs.
Fig. 1 — Single-diagonal brace connection at beam-column corner. Shows gusset plate, bolt group, 30° Whitmore fan (Lw), Thornton length (Lt), UFM interface forces (Hb, Vc), and brace angle (θ). The live calculator diagram updates dynamically as you change inputs.
Understanding the Load Path
Every check in the calculator follows the force as it travels through the connection. Getting this sequence right is the key to understanding why certain limit states govern:
| Step | Element | Force Transferred | Limit States Checked |
|---|---|---|---|
| 1 | Brace Member | Axial Pᵤ (tension or compression) | Yielding, rupture, block shear, buckling (KL/r) |
| 2 | Brace-to-Gusset (Bolts or Welds) | Pᵤ transferred via fasteners | Bolt shear, bearing, tear-out; weld rupture |
| 3 | Gusset Plate (Whitmore section) | Distributed stress on Whitmore width | Tensile yielding, rupture, Thornton compression buckling |
| 4 | Gusset Interfaces (UFM) | Hb, Vb to beam; Hc, Vc to column | Interface shear yielding, shear rupture, block shear |
| 5 | Beam Web / Column Web | Local concentrated forces | Web local yielding, web crippling (J10) |
Table 1 — Force load path sequence for a brace connection per AISC 360-22. The calculator checks all five stages automatically.
🔧 Step-by-Step Input Guide
Follow these steps in order. The calculator tabs mirror this sequence: Configuration → Loads → Geometry → Bolts/Welds → Results.
Step 1 — Select Unit System & Design Method
1
Choose Imperial or Metric — then LRFD or ASD
Click the
Imperial (kip, in) or Metric (kN, mm) toggle at the top of the Configuration tab. All inputs and outputs switch simultaneously. Then select LRFD or ASD; resistance factors (φ) or safety factors (Ω) update automatically throughout every formula.
⚠ Common mistake: Do not mix units. If you enter Pu in kips but have switched to Metric, results will be wrong. Always confirm the unit badge next to each input field matches your intended units.
| Design Method | Tension Yield (φt / Ωt) | Tension Rupture (φt / Ωt) | Compression (φc / Ωc) | Shear (φv / Ωv) | Block Shear (φ / Ω) |
|---|---|---|---|---|---|
| LRFD | 0.90 | 0.75 | 0.90 | 1.00 | 0.75 |
| ASD | 1/1.67 = 0.599 | 1/2.00 = 0.500 | 1/1.67 = 0.599 | 1/1.50 = 0.667 | 1/2.00 = 0.500 |
Table 2 — Resistance factors (LRFD) and safety factors (ASD) applied automatically per AISC 360-22.
Step 2 — Brace Configuration & Member Sections
2
Select brace type, connection type, and member sections
Choose your Brace Type (Single Diagonal, X-Brace, Chevron, Inverted-V, Knee). Choose Connection Type—Bolted Gusset, Welded Gusset, or Hybrid. Select the Brace Member Shape and Size; gross area Ag and radius of gyration ry auto-populate from the AISC shape database.
⚠ Common mistake: For HSS members, ensure you select the correct wall thickness. HSS5x5x3/8 and HSS5x5x5/16 have meaningfully different Ag values. Always verify the auto-populated Ag against your design drawings.
Ag — Gross Area in² / mm²
Cross-sectional area of the brace member. For HSS: use total wall area; for W-shapes: tabulated A from AISC Steel Construction Manual.
⚠ Must be > 0. Valid range: 0.5–60 in² for typical brace sections.
ry — Radius of Gyration (weak axis) in / mm
Weak-axis radius used for KL/r compression slenderness check. For HSS: rx = ry. For W-shapes: ry is typically the smaller value.
⚠ If brace is oriented with strong axis, use rx instead. Mistaking the two is a common error in compression checks.
Fy — Yield Stress ksi / MPa
Minimum specified yield stress. A36 = 36 ksi (248 MPa); A572 Gr.50 = 50 ksi (345 MPa); A992 = 50 ksi.
Fu — Ultimate Tensile Stress ksi / MPa
Minimum specified tensile strength. A36 = 58 ksi; A572 Gr.50 = 65 ksi; A992 = 65 ksi. Used in rupture and block shear checks.
⚠ Do not use Fy where Fu is required. Rupture checks always use Fu, not Fy.
Step 3 — Applied Loads & UFM Parameters
3
Enter factored brace force, angle, and UFM geometry
Enter Pu Tension and Pu Compression separately (kips or kN). The calculator uses the governing (higher) demand for shared limit states. Enter the brace angle θ from horizontal (5°–85°). The live diagram updates.
⚠ Common mistake (LRFD): Enter factored loads (1.2D + 1.6L etc.), not service loads. For ASD: enter service (unfactored) loads. The method toggle changes how the calculator interprets your input.
Pu Tension kips / kN
Factored tensile demand on the brace. Use maximum from governing LRFD load combination (e.g., 1.2D + 1.0W).
Pu Compression kips / kN
Factored compressive demand. Tension and compression cases are both checked; compression governs the Thornton buckling check.
θ — Brace Angle from Horizontal degrees (°)
Measured from horizontal (beam axis) to the brace centerline. 45° is most common. Affects UFM horizontal and vertical component resolution.
⚠ Angles below 20° or above 75° produce very large interface forces on one member. Keep 30°–60° for economy.
α — UFM Horizontal Parameter in / mm
Horizontal distance from column face to centroid of gusset-beam weld or bolt group interface. Used to split the brace force between beam and column per the Uniform Force Method.
β — UFM Vertical Parameter in / mm
Vertical distance from beam face to centroid of gusset-column weld or bolt group interface.
Step 4 — Gusset Plate Geometry
4
Define the gusset plate and Whitmore / Thornton parameters
Enter plate thickness tgp, Whitmore width Lw, and Thornton length Lt. The Whitmore width can be computed automatically by the formula (see Section 5c) or entered manually if you have already sketched it. Choose whether a free-edge stiffener is provided; if yes, the compression buckling check is bypassed.
⚠ Common mistake: Thornton length Lt is measured from the Whitmore section to the nearest free edge of the gusset, not to the bolt group or weld termination. Measuring to the wrong point leads to non-conservative buckling results.
Step 5 — Bolt Design Inputs
5
Enter bolt grade, size, pattern, and hole type
Select Bolt Grade (A325-N, A325-X, A490-N, A490-X, or slip-critical variants). Choose Bolt Diameter (5/8” to 1-1/2”). Enter Rows × Columns for the bolt group. Set Spacing s (min 2.67db, recommended 3db) and Edge Distance e1. Choose Hole Type (Standard, Oversize, Slotted).
⚠ Common mistake: AISC Table J3.4 requires minimum edge distances based on bolt diameter. For 7/8” bolts, minimum e1 = 1-1/8” (sheared edge) or 1” (rolled edge). Entering edge distances smaller than these will give unconservative bearing results.
Step 6 — Weld Design Inputs
6
Set electrode classification, fillet size, length, and configuration
Select Electrode (E70XX, E80XX, E90XX). Enter Fillet Weld Size w in 1/16” increments. Enter Weld Length Lw per weld line. Choose Configuration (one-sided, two-sided, boxed). Enter the load angle to weld axis θw for the directional strength increase factor.
⚠ Common mistake: The minimum fillet weld size per AISC Table J2.4 is based on the thicker connected part thickness—not the thinner one. For a 1/2” gusset plate, minimum weld size = 3/16”. Using a smaller weld will fail the minimum-size check even if demand is low.
Step 7 — Seismic SCBF / OCBF Settings (if applicable)
7
Enable SCBF mode for seismic design provisions
If the structure is in a seismic design category (SDC) C through F and the Seismic Force-Resisting System (SFRS) is a Special Concentrically Braced Frame (SCBF), set the Seismic Mode dropdown to SCBF. The calculator then activates: RyFyAg expected brace strength, 2t ellipse clearance requirement, and modified resistance factors per AISC 341-16.
⚠ Common mistake: For SCBF, the brace connection must be designed for the expected yield strength RyFyAg—not the nominal factored load Pu. Failing to activate SCBF mode on a seismic project leads to a severely under-designed connection that will fracture before the brace can yield and dissipate energy.
ƒ All Calculation Formulas Explained
This section documents every formula used in the SteelSolver Brace Connection Calculator, organized by limit state category. All equations follow AISC 360-22 unless noted otherwise. Variables are defined where first introduced.
5a. Brace Member Tension Checks
Tensile Yielding on Gross Area
AISC 360-22 Equation D2-1 | φt = 0.90 (LRFD)
$$\phi_t P_n = \phi_t \cdot F_y \cdot A_g$$
When it governs: Short braces with large gross areas and low Fu/Fy ratio. Yielding is the ductile limit state; a well-designed brace connection should not govern by rupture before yielding.
Variables: Fy = yield stress (ksi); Ag = gross cross-sectional area (in²).
§ D2, AISC 360-22
Variables: Fy = yield stress (ksi); Ag = gross cross-sectional area (in²).
Tensile Rupture on Net Area
AISC 360-22 Equation D2-2 | φt = 0.75 (LRFD)
$$\phi_t P_n = \phi_t \cdot F_u \cdot A_e$$
$$A_e = U \cdot A_n, \quad A_n = A_g - \sum (d_h \cdot t)$$
Variables: Fu = ultimate tensile stress; Ae = effective net area (in²); U = shear lag factor from AISC Table D3.3 (0.60–1.00 depending on connection type and length); An = net area after deducting bolt holes; dh = hole diameter (dbolt + 1/16” per AISC §B4.3b); t = element thickness.
Shear lag factor U: For HSS with a welded connection to all walls, U = 1.0. For a bolted single angle with 4+ bolts, U ≈ 0.80. For most double-angle braces, U = 0.85–0.90.
§ D2 & D3, Table D3.3, AISC 360-22
Shear lag factor U: For HSS with a welded connection to all walls, U = 1.0. For a bolted single angle with 4+ bolts, U ≈ 0.80. For most double-angle braces, U = 0.85–0.90.
Block Shear Rupture (Brace)
AISC 360-22 Equation J4-5 | φ = 0.75 (LRFD)
$$\phi R_n = \phi \bigl[0.6\,F_u\,A_{nv} + U_{bs}\,F_u\,A_{nt}\bigr] \;\le\; \phi \bigl[0.6\,F_y\,A_{gv} + U_{bs}\,F_u\,A_{nt}\bigr]$$
Block shear is a combined failure where a "block" of material tears out along shear and tension planes simultaneously. It is one of the most commonly missed checks on brace connections.
Variables: Anv = net shear area; Ant = net tension area; Agv = gross shear area; Ubs = 1.0 for uniform tension stress (typical for brace connections), 0.5 for non-uniform.
§ J4.3, AISC 360-22
Variables: Anv = net shear area; Ant = net tension area; Agv = gross shear area; Ubs = 1.0 for uniform tension stress (typical for brace connections), 0.5 for non-uniform.
5b. Brace Member Compression (Flexural Buckling)
AISC 360-22 §E3 | φc = 0.90 (LRFD)
$$F_e = \frac{\pi^2 E}{(KL/r)^2} \quad \text{(Elastic Euler stress)}$$
$$\phi_c F_{cr} = \begin{cases} \phi_c\,(0.658^{F_y/F_e})\,F_y & \text{if } KL/r \le 4.71\sqrt{E/F_y} \\ \phi_c\,(0.877\,F_e) & \text{if } KL/r > 4.71\sqrt{E/F_y} \end{cases}$$
$$\phi_c P_n = \phi_c F_{cr} \cdot A_g$$
Variables: K = effective length factor (use 0.65 for a typical braced frame brace with fixed ends); L = unbraced length (in); r = governing radius of gyration; E = 29,000 ksi (200,000 MPa); Fcr = critical buckling stress.
Slenderness limit: For A572 Gr.50 (Fy = 50 ksi), the limit KL/r = 4.71√(29000/50) = 113. If KL/r exceeds 200, a slenderness warning is shown (AISC §E2 recommended limit).
Note on K: AISC recommends K = 0.65 for braces with gusset-plate end conditions that provide some rotational restraint. Use K = 1.0 if both ends are truly pinned.
§ E3, AISC 360-22 Eqs. E3-2 & E3-3
Slenderness limit: For A572 Gr.50 (Fy = 50 ksi), the limit KL/r = 4.71√(29000/50) = 113. If KL/r exceeds 200, a slenderness warning is shown (AISC §E2 recommended limit).
Note on K: AISC recommends K = 0.65 for braces with gusset-plate end conditions that provide some rotational restraint. Use K = 1.0 if both ends are truly pinned.
5c. Gusset Plate — Whitmore Section Analysis
Whitmore Width Calculation
Whitmore (1952) / AISC 360-22 §J4.4
$$L_w = L_{bolt\text{-}group} + 2\,L_{conn}\,\tan 30°$$
$$A_w = t_{gp} \cdot L_w$$
The Whitmore section is a notional plane perpendicular to the brace axis at the end of the connection, where the brace force is assumed to have spread at 30° from each side of the bolt group or weld toe. It represents the effective cross-sectional area of the gusset plate resisting the brace force.
Variables: Lbolt-group = length of the bolt group or weld along the brace axis; Lconn = same connection length; tgp = gusset plate thickness; Aw = Whitmore area used in tensile yielding and rupture checks.
§ J4.4, AISC 360-22; Whitmore, R.E. (1952)
Variables: Lbolt-group = length of the bolt group or weld along the brace axis; Lconn = same connection length; tgp = gusset plate thickness; Aw = Whitmore area used in tensile yielding and rupture checks.
Gusset Plate Tensile Yielding (Whitmore Section)
φ = 0.90 (LRFD)
$$\phi R_n = \phi \cdot F_{y,gp} \cdot A_w = \phi \cdot F_{y,gp} \cdot t_{gp} \cdot L_w$$
Where Fy,gp is the yield stress of the gusset plate material (typically 36 ksi for A36 or 50 ksi for A572 Gr.50).
§ J4.1, AISC 360-22
5d. Gusset Plate — Thornton Compression Buckling
Thornton Method (1991) / AISC Design Guide 29
$$r_{gp} = \frac{t_{gp}}{\sqrt{12}} \quad \text{(gusset plate radius of gyration)}$$
$$\frac{KL_t}{r_{gp}} \quad \text{(Thornton KL/r for compression buckling)}$$
$$\phi_c F_{cr} \text{ from AISC } \S E3 \text{ using above KL/r}$$
$$\phi_c R_n = \phi_c F_{cr} \cdot A_w$$
When the brace is in compression, the gusset plate acts as a column strip (the Whitmore strip) between the Whitmore section and the nearest free edge. The Thornton method treats this strip as a column with effective length K·Lt.
Variables: Lt = Thornton length = distance from Whitmore section to nearest gusset free edge; K = 0.65 (both edges restrained by beam/column), 1.2 (one free edge), 2.0 (cantilever).
Rule of thumb: If KLt/r ≤ 25, the gusset plate will yield before buckling and this check is rarely governing.
Thornton, W.A. (1991). AISC Eng. Journal. AISC Design Guide 29.
Variables: Lt = Thornton length = distance from Whitmore section to nearest gusset free edge; K = 0.65 (both edges restrained by beam/column), 1.2 (one free edge), 2.0 (cantilever).
Rule of thumb: If KLt/r ≤ 25, the gusset plate will yield before buckling and this check is rarely governing.
5e. Gusset Plate — Shear Yielding & Shear Rupture at Interfaces
Shear Yielding — AISC 360-22 Eq. J4-3 | φv = 1.00
$$\phi R_n = \phi \cdot 0.6\,F_{y,gp} \cdot A_{gv}$$
Shear Rupture — AISC 360-22 Eq. J4-4 | φ = 0.75
$$\phi R_n = \phi \cdot 0.6\,F_{u,gp} \cdot A_{nv}$$
At the gusset-to-beam and gusset-to-column interfaces, the UFM resolves Hb, Vb, Hc, Vc as the governing demands. Agv and Anv are the gross and net areas of the interface (length × tgp, minus any bolt holes).
§ J4.2, AISC 360-22
5f. Uniform Force Method (UFM) — Interface Force Distribution
The Uniform Force Method (AISC SCM 15th Ed., Part 13) is the standard approach for distributing the brace axial force into the gusset-to-beam and gusset-to-column interfaces without introducing a net moment. It assumes uniform shear stress along each interface.
UFM Interface Force Equations — AISC SCM 15th Ed. Part 13 / AISC 360-22 Commentary C-J1
$$r = \sqrt{(\bar{\alpha} + e_b)^2 + (\bar{\beta} + e_c)^2}$$
$$H_b = P_u \cdot \frac{\bar{\alpha}}{r}\,\sin\theta \quad \text{(Horiz. force at beam interface)}$$
$$V_b = P_u \cdot \frac{e_b}{r}\,\sin\theta \quad \text{(Vert. force at beam interface)}$$
$$H_c = P_u \cdot \frac{e_c}{r}\,\cos\theta \quad \text{(Horiz. force at column interface)}$$
$$V_c = P_u \cdot \frac{\bar{\beta}}{r}\,\cos\theta \quad \text{(Vert. force at column interface)}$$
Variables:
ᾱ (alpha-bar) = horizontal distance from column face to centroid of gusset-to-beam connection
β̄ (beta-bar) = vertical distance from beam face to centroid of gusset-to-column connection
eb = half the beam depth (dbeam/2)
ec = half the column depth (dcol/2)
r = resultant eccentricity distance
Hb, Vb = horizontal and vertical forces at gusset-beam interface
Hc, Vc = horizontal and vertical forces at gusset-column interface
UFM Moment-Free Condition: The method is moment-free when ᾱ tanθ = β̄. If your geometry does not satisfy this, a net moment acts at one interface and must be added to the demand.
AISC SCM 15th Ed. Part 13; Commentary C-J1, AISC 360-22
ᾱ (alpha-bar) = horizontal distance from column face to centroid of gusset-to-beam connection
β̄ (beta-bar) = vertical distance from beam face to centroid of gusset-to-column connection
eb = half the beam depth (dbeam/2)
ec = half the column depth (dcol/2)
r = resultant eccentricity distance
Hb, Vb = horizontal and vertical forces at gusset-beam interface
Hc, Vc = horizontal and vertical forces at gusset-column interface
UFM Moment-Free Condition: The method is moment-free when ᾱ tanθ = β̄. If your geometry does not satisfy this, a net moment acts at one interface and must be added to the demand.
5g. Bolt Shear, Bearing & Tear-Out
Bolt Shear Strength — AISC 360-22 Eq. J3-1 | φ = 0.75
$$\phi r_n = \phi \cdot F_{nv} \cdot A_b \quad \text{per bolt per shear plane}$$
$$\phi R_n^{group} = \phi \cdot F_{nv} \cdot A_b \cdot n_{planes} \cdot n_{bolts}$$
Fnv values: A325-N = 54 ksi; A325-X = 54 ksi; A490-N = 68 ksi; A490-X = 68 ksi. Ab = bolt cross-sectional area = πdb²/4. nplanes = 1 (single shear) or 2 (double shear).
Table J3.2, AISC 360-22
Bolt Bearing on Connected Part — AISC 360-22 Eq. J3-6a | φ = 0.75
$$\phi r_n = \phi \cdot 2.4\,F_u\,d_b\,t \quad \text{(interior bolt, standard hole)}$$
Bearing is checked on both the gusset plate and the brace member. The thinner or lower-Fu material governs. Fu here is the tensile strength of the connected material, not the bolt.
§ J3.10, AISC 360-22
Bolt Tear-Out (Edge Bolt) — AISC 360-22 Eq. J3-6c | φ = 0.75
$$\phi r_n = \phi \cdot 1.2\,F_u\,l_c\,t, \quad l_c = e_1 - \frac{d_h}{2}$$
Where lc = clear distance from edge of hole to edge of material. This limit state governs when edge distance is small.
§ J3.10, AISC 360-22
5h. Fillet Weld Strength — Directional Method
AISC 360-22 Eq. J2-4 | φ = 0.75
$$k = 1 + 0.5\,\sin^{1.5}\theta_w \quad \text{(directional strength factor)}$$
$$\phi R_n = \phi \cdot 0.6\,F_{EXX} \cdot (0.707\,w) \cdot L_w \cdot k \cdot n_{sides}$$
The directional method accounts for the angle of loading relative to the weld axis. A weld loaded perpendicular (θw = 90°) is 50% stronger than one loaded parallel (θw = 0°).
Variables: FEXX = electrode classification strength (70 ksi for E70XX); w = fillet weld leg size (in); Lw = weld length; k = directional factor (k = 1.0 at 0°; k = 1.50 at 90°); nsides = number of weld lines (1, 2, or 4 for boxed).
Effective throat: 0.707·w for a 45° fillet weld.
Minimum weld size (AISC Table J2.4): Based on thicker connected part. For t = 3/8”, min w = 3/16”; for t = 1/2”–3/4”, min w = 1/4”.
§ J2.4, Eq. J2-4, AISC 360-22; Table J2.4
Variables: FEXX = electrode classification strength (70 ksi for E70XX); w = fillet weld leg size (in); Lw = weld length; k = directional factor (k = 1.0 at 0°; k = 1.50 at 90°); nsides = number of weld lines (1, 2, or 4 for boxed).
Effective throat: 0.707·w for a 45° fillet weld.
Minimum weld size (AISC Table J2.4): Based on thicker connected part. For t = 3/8”, min w = 3/16”; for t = 1/2”–3/4”, min w = 1/4”.
5i. Seismic SCBF Provisions (AISC 341-16)
Expected Brace Strength — AISC 341-16 Eq. F2-3
$$T_{expected} = R_y \cdot F_y \cdot A_g$$
For SCBF, the connection must be designed for the expected yield strength of the brace, not the nominal factored demand Pu. Ry = ratio of expected yield stress to Fy: 1.1 for A36, 1.1 for A500/A572, 1.1 for A992 (hot-rolled shapes).
Table A3.2, AISC 341-16
2t Ellipse Gusset Hinge Clearance — AISC 341-16 §F2.6c.4
$$\text{Clearance} \ge 2\,t_{gp}$$
For SCBF, the gusset plate must be detailed to permit in-plane rotation (hinging) as the brace buckles in compression. A minimum clearance of 2×tgp between the gusset free edge and the brace member (measured along the hinge line) ensures the plate can form a plastic hinge without tearing.
This check is automatic when SCBF mode is enabled. Enter the actual clearance in the Geometry tab; the calculator flags it as PASS or FAIL.
§ F2.6c.4, AISC 341-16
This check is automatic when SCBF mode is enabled. Enter the actual clearance in the Geometry tab; the calculator flags it as PASS or FAIL.
📈 Input Reference Table & Valid Ranges
Use this table to quickly verify your inputs are within realistic design ranges. Values outside these ranges will not cause the calculator to crash, but should be double-checked for engineering reasonableness.
| Input Parameter | Symbol | Imperial Unit | Metric Unit | Typical Range | Notes / Validation |
|---|---|---|---|---|---|
| Factored Tensile Force | Pu,t | kips | kN | 10–1000 kips | Must be ≥ 0. Use LRFD factored or ASD service load. |
| Factored Comp. Force | Pu,c | kips | kN | 10–800 kips | Compression capacity limited by KL/r; very slender braces may be tension-only. |
| Brace Angle | θ | degrees | degrees | 20°–70° | Angles <20° or >70° create very large interface forces; avoid for economy. |
| Gross Area (Brace) | Ag | in² | mm² | 0.5–50 in² | Auto-populates from shape selection. Verify against AISC shape tables. |
| Yield Stress | Fy | ksi | MPa | 36–65 ksi | Do not use Fu here. Values >65 ksi require special verification. |
| Ultimate Stress | Fu | ksi | MPa | 58–90 ksi | Always Fu > Fy. A36: 58 ksi; A572 Gr.50: 65 ksi. |
| Gusset Thickness | tgp | in | mm | 0.25–1.5 in | Available in 1/16” plate increments (0.0625 in steps). |
| Whitmore Width | Lw | in | mm | 4–24 in | Must not exceed gusset plate width. Check that Lw ≤ gusset width. |
| Thornton Length | Lt | in | mm | 2–18 in | Measured from Whitmore section to nearest free gusset edge. Not the same as gusset height. |
| UFM Alpha | ᾱ | in | mm | 3–16 in | Horizontal distance from column face to centroid of beam interface connection. |
| UFM Beta | β̄ | in | mm | 2–14 in | Vertical distance from beam face to centroid of column interface connection. |
| Bolt Diameter | db | in | mm | 5/8”–1.5” | 3/4” and 7/8” most common for brace connections. |
| Bolt Spacing | s | in | mm | 2db–6 in | Minimum 2.67db; preferred 3db. AISC Table J3.3. |
| Edge Distance | e1 | in | mm | 1.0”–3” | Minimum per AISC Table J3.4. For 7/8” bolt: e1,min = 1-1/8”. |
| Fillet Weld Size | w | in | mm | 3/16”–5/8” | Enter in 1/16” increments. Max = tgp − 1/16” for edges ≥ 1/4” thick. |
| Brace Unbraced Length | Lb | in | mm | 60–360 in | Center-to-center of gusset connections. Keep KL/r ≤ 200 (recommended). |
| Shear Lag Factor | U | — | — | 0.60–1.00 | From AISC Table D3.3. Use 0.85 for double-angle with 4+ bolts in a single row; 1.0 for all-welded HSS. |
Table 3 — Input parameters, units, typical ranges, and validation notes for the Brace Connection Calculator.
✅ Reading & Interpreting Results
After entering all inputs, navigate to the Results tab. Results are displayed in three layers: summary cards at the top, a detailed limit-state table, and color-coded utilization bars.
Understanding the DCR (Demand-to-Capacity Ratio)
| DCR Value | Status | Bar Color | Meaning & Action |
|---|---|---|---|
| ≤ 0.75 | ✔ PASS | Green | Good margin. Connection is comfortably adequate. Consider whether it is over-designed (un-economical). |
| 0.75 – 1.00 | ⚠ PASS | Yellow | Adequate but close to limit. Acceptable for final design; flag for sensitivity review. |
| > 1.00 | ✖ FAIL | Red | Overstressed. Connection is unsafe as configured. Increase capacity (larger plate, more bolts, larger weld) or reduce demand (re-route load). |
The Governing Limit State
The row with the highest DCR is flagged as the governing limit state with an orange “GOVERNS” badge. This is the element that will fail first if the load is increased. The Summary Cards at the top show:
- Governing Limit State: Name of the controlling check (e.g., “Bolt Shear (6 bolts)”)
- Max DCR: The highest demand-to-capacity ratio across all checks
- Overall Status: PASS if all DCR ≤ 1.0; FAIL if any DCR > 1.0
- Connection Capacity: The lowest absolute capacity value across all limit states (kips or kN)
How to Fix a Failing Check
| Failing Limit State | Quick Fix | Better Fix |
|---|---|---|
| Bolt Shear | Add more bolts (increase rows or columns) | Upgrade to A490 or use double-shear configuration |
| Bolt Bearing | Increase gusset plate thickness | Increase edge and end distances; use higher Fu plate |
| Fillet Weld Rupture | Increase weld size (next 1/16” increment) | Add return welds or switch to two-sided weld |
| Gusset Tensile Yielding | Increase tgp or use A572 instead of A36 | Increase Whitmore width (larger bolt group) |
| Thornton Buckling | Increase tgp (increases rgp) | Add free-edge stiffener (eliminates check) |
| Block Shear | Add a bolt row (increases Anv) | Increase gusset plate thickness |
| Brace Tensile Rupture | Use a larger brace section | Reduce hole deductions (spread bolts in 2 rows) |
| Brace Compression Buckling | Reduce unbraced length Lb | Use a section with higher r (HSS over angles) |
Table 4 — Recommended remedies for common failing limit states.
📚 Complete Limit State Reference Table
The table below lists all limit states checked by the calculator, their AISC 360-22 code reference, the resistance factor, and the governing demand used.
| # | Limit State | AISC 360-22 Ref. | φ (LRFD) | Demand Used | Element |
|---|---|---|---|---|---|
| 1 | Tensile Yielding (Gross) | Eq. D2-1 | 0.90 | Pu,tension | Brace member |
| 2 | Tensile Rupture (Net) | Eq. D2-2 | 0.75 | Pu,tension | Brace member |
| 3 | Compression Buckling (KL/r) | §E3, Eqs. E3-2/E3-3 | 0.90 | Pu,compression | Brace member |
| 4 | Gusset Tensile Yielding (Whitmore) | §J4.1 / §J4.4 | 0.90 | Pu,tension | Gusset plate |
| 5 | Gusset Compression Buckling (Thornton) | DG29, §E3 | 0.90 | Pu,compression | Gusset plate |
| 6 | Gusset Shear Yielding (Beam Interface) | Eq. J4-3 | 1.00 | Hb (UFM) | Gusset plate |
| 7 | Block Shear Rupture | Eq. J4-5 | 0.75 | Pu (governing) | Gusset plate |
| 8 | Bolt Shear (Group) | Eq. J3-1 | 0.75 | Pu (governing) | Bolt group |
| 9 | Bolt Bearing (Gusset) | Eq. J3-6a | 0.75 | Pu (governing) | Bolt / Gusset |
| 10 | Bolt Tear-Out (Edge Bolts) | Eq. J3-6c | 0.75 | Pu (governing) | Bolt / Gusset |
| 11 | Fillet Weld Rupture (Directional) | Eq. J2-4 | 0.75 | Pu (governing) | Weld |
| 12* | SCBF: Expected Brace Strength (RyFyAg) | AISC 341 Eq. F2-3 | 0.90 | RyFyAg | Connection system |
| 13* | SCBF: 2t Ellipse Clearance | AISC 341 §F2.6c.4 | — | 2×tgp | Gusset plate |
Table 5 — All limit states checked by the calculator. *Items 12–13 activate only when SCBF or OCBF seismic mode is enabled.
⚠ Common Mistakes & Microcopy Guide
These are the most frequent input errors engineers and students make when using brace connection calculators. Each warning is also shown in-line next to the relevant input field in the calculator.
Top 10 Input Errors to Avoid
- Confusing An and Ae. The net area An removes holes; the effective net area Ae = U·An further reduces An by the shear lag factor U. Always apply U for rupture checks.
- Wrong Thornton length Lt. Lt is the distance from the Whitmore section plane to the nearest free edge of the gusset—not from the bolt group to the gusset corner. Measuring to the wrong point is one of the most common errors in gusset plate design.
- Using K = 1.0 for all braces. Braces with welded gusset plates at both ends have rotational restraint. AISC recommends K = 0.65 for these conditions. Using K = 1.0 leads to conservative (uneconomical) compression checks.
- Entering service loads for LRFD. LRFD requires factored loads. If your analysis software outputs service loads (dead and live separately), you must apply the load combinations (1.2D + 1.6L, etc.) before entering Pu.
- Forgetting shear lag for HSS with partial connection. An HSS connected through a slotted plate to only two walls has significant shear lag (U < 1.0 per Table D3.3). Not deducting for shear lag is non-conservative and a common omission.
- Using the brace member Fu for bolt bearing. Bolt bearing capacity uses the Fu of the connected plate or member, not the bolt. The gusset plate and the brace member are checked separately, and the weaker one governs.
- Neglecting the weld minimum size. A weld that passes the strength check can still fail the code minimum-size requirement per AISC Table J2.4. Always verify that w ≥ minimum weld size for the connected part thickness.
- Ignoring SCBF mode on seismic projects. Designing for the analysis Pu alone on an SCBF brace connection will produce an under-designed connection. The connection must be designed for RyFyAg of the brace.
- Selecting the wrong bolt shear plane. A typical gusset-plate brace connection uses single shear (one shear plane per bolt). Double shear applies only when the brace or gusset is sandwiched between two plates.
- Not checking both tension and compression demands. Some brace connections carry tension under one load combination and compression under another (e.g., wind reversals). Always enter both Pu,t and Pu,c for a complete design.
🔢 Accuracy Note & Engineering Disclaimer
The SteelSolver Brace Connection Calculator implements the AISC 360-22 analytical equations as described in this guide. Numerical results have been cross-checked against published AISC design examples and are accurate to within normal floating-point precision for the implemented checks.
Limitations you should be aware of:
- Web local yielding and web crippling checks (AISC §J10) on the beam and column are not currently included. For connections at column webs or near beam ends, verify these separately.
- The block shear check uses a simplified path geometry. Complex multi-path block shear (e.g., L-shaped tear-out) should be verified by hand for unusual bolt patterns.
- The UFM implementation assumes the standard beam-column corner configuration with moment-free interfaces. Non-concentric work points require additional moment calculations not included here.
- Seismic checks implement AISC 341-16. If your project references AISC 341-22, verify any code differences independently.
- This tool is intended for preliminary and educational design. All final designs must be reviewed and stamped by a licensed Professional Engineer with independent verification of calculations.
Trust indicators: Every result row displays the exact AISC equation number used and the demand and capacity values. You can trace every DCR to its formula above. If any result surprises you, check the input that feeds it using the formula documentation in Section 5.
❓ Frequently Asked Questions (FAQ)
A bolted gusset plate connection transfers the brace force through bolt shear and bearing into the gusset plate, which is then connected to the beam and column by additional bolts or welds. It is field-adjustable and easier to inspect, but requires more material (holes reduce net area) and is more expensive in labor.
A welded gusset plate connection uses continuous fillet or groove welds to transfer the brace force. Welds achieve higher efficiency per unit area, eliminate net area reductions, and are common in seismic design where compact connections reduce eccentricity. However, welds require qualified welders and are more difficult to modify after erection.
A hybrid connection bolts the brace to the gusset and welds the gusset to the beam/column—the most common arrangement for braced frames in North America.
A welded gusset plate connection uses continuous fillet or groove welds to transfer the brace force. Welds achieve higher efficiency per unit area, eliminate net area reductions, and are common in seismic design where compact connections reduce eccentricity. However, welds require qualified welders and are more difficult to modify after erection.
A hybrid connection bolts the brace to the gusset and welds the gusset to the beam/column—the most common arrangement for braced frames in North America.
The Whitmore section is an imaginary plane drawn perpendicular to the brace axis at the end of the bolt group or weld, where the brace force has spread through the gusset at 30° from each side of the connection. It is the critical cross-section of the gusset plate under the brace force.
It matters because the gusset plate is thinner than the brace member, and if the Whitmore area (Lw × tgp) is too small, the plate will yield or rupture in tension, or buckle under compression, before the brace reaches its design load. The Whitmore section check is AISC 360-22 §J4.4 and is part of every complete brace connection design.
It matters because the gusset plate is thinner than the brace member, and if the Whitmore area (Lw × tgp) is too small, the plate will yield or rupture in tension, or buckle under compression, before the brace reaches its design load. The Whitmore section check is AISC 360-22 §J4.4 and is part of every complete brace connection design.
The brace angle θ appears in two critical places: (1) the UFM force resolution, where Hb = Pu·cosθ and Vc = Pu·sinθ, and (2) the gusset plate geometry (how the Whitmore fan is oriented relative to the plate edges).
Changing θ shifts force between the beam and column interfaces. At θ = 45°, forces are approximately equally split. At a shallow angle (θ = 20°), most force goes to the beam; at a steep angle (θ = 70°), most goes to the column. This is why the live diagram updates when you change the angle—to help you understand the geometry before committing to a plate configuration.
Changing θ shifts force between the beam and column interfaces. At θ = 45°, forces are approximately equally split. At a shallow angle (θ = 20°), most force goes to the beam; at a steep angle (θ = 70°), most goes to the column. This is why the live diagram updates when you change the angle—to help you understand the geometry before committing to a plate configuration.
Both methods are acceptable per AISC 360-22. LRFD (Load and Resistance Factor Design) applies load factors to demands and resistance factors to capacities; it generally produces more economical designs for steel structures with well-defined load combinations. ASD (Allowable Strength Design) divides nominal capacity by a safety factor; it is more familiar to engineers working on legacy projects or interfacing with older codes.
For most new steel building design in North America, LRFD is recommended. For projects where the client or Authority Having Jurisdiction specifies ASD, use the ASD toggle. The calculator automatically adjusts all factors when you switch methods.
For most new steel building design in North America, LRFD is recommended. For projects where the client or Authority Having Jurisdiction specifies ASD, use the ASD toggle. The calculator automatically adjusts all factors when you switch methods.
Yes, as long as all individual limit state DCRs are ≤ 1.0. The connection is valid if every check passes, regardless of which element has more relative capacity. The governing (lowest-capacity) check determines the overall connection strength.
However, AISC §J1.8 specifies that welds and bolts shall not be designed to share load in the same force direction (with limited exceptions for existing connections). If you have a hybrid connection where bolts resist the brace-to-gusset force and welds resist the gusset-to-frame force, they are in different load paths and can be designed independently. Make sure your connection type selection in the calculator reflects this correctly.
However, AISC §J1.8 specifies that welds and bolts shall not be designed to share load in the same force direction (with limited exceptions for existing connections). If you have a hybrid connection where bolts resist the brace-to-gusset force and welds resist the gusset-to-frame force, they are in different load paths and can be designed independently. Make sure your connection type selection in the calculator reflects this correctly.
Select Chevron / V-Brace from the Brace Type dropdown and set Frame Location to Beam Midspan. For a Chevron brace, both diagonal members connect to a single point on the beam at midspan. The vertical force imbalance from the two braces must be transferred to the beam as an additional vertical demand.
In the Loads tab, enter the Beam Loads > Beam Shear as the vertical unbalanced force from the two braces (Pu,compression·sinθ − Pu,tension·sinθ). AISC 341 SCBF provisions require special attention for Chevron configurations: the beam must be designed for the post-buckling unbalanced load, typically using Ry overstrength for the tension brace.
In the Loads tab, enter the Beam Loads > Beam Shear as the vertical unbalanced force from the two braces (Pu,compression·sinθ − Pu,tension·sinθ). AISC 341 SCBF provisions require special attention for Chevron configurations: the beam must be designed for the post-buckling unbalanced load, typically using Ry overstrength for the tension brace.
The governing limit state is the check with the highest DCR (demand-to-capacity ratio)—the element that is most highly stressed relative to its capacity. It is the first element that would fail if the applied load were increased beyond the design load.
In a well-proportioned design, the governing limit state is intentional: for ductile seismic design, the brace member yielding in tension (DCR on Eq. D2-1) should govern—not weld rupture or bolt shear, which are brittle. The AISC 341 “balanced design” philosophy specifically aims to ensure yielding governs over fracture.
In a well-proportioned design, the governing limit state is intentional: for ductile seismic design, the brace member yielding in tension (DCR on Eq. D2-1) should govern—not weld rupture or bolt shear, which are brittle. The AISC 341 “balanced design” philosophy specifically aims to ensure yielding governs over fracture.
The current version implements AISC 360-22 exclusively. While many of the underlying engineering concepts are similar (net area rupture, block shear, bolt bearing), the specific partial factors (γM), formulas, and minimum requirements differ between Eurocode 3 (EN 1993-1-8) and AISC 360.
If your project follows Eurocode 3, you can still use this calculator to understand the force flow and get an order-of-magnitude check, but you must verify all limit states against the EN 1993 equations before finalizing. A Eurocode 3 module is a planned future feature for SteelSolver.com.
If your project follows Eurocode 3, you can still use this calculator to understand the force flow and get an order-of-magnitude check, but you must verify all limit states against the EN 1993 equations before finalizing. A Eurocode 3 module is a planned future feature for SteelSolver.com.
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