Design every steel connection to AISC 360 Chapter J.

ILX Connection is a Windows desktop application for structural steel connection design. Build a connection from standard W-shape sections, plates, bolts, and welds in a real-time 3D viewport, then run a Component-Based Finite Element Method (CBFEM) analysis with AISC 360-16 design checks and a printable PDF report — all in one tool, with no FEA pre/post-processing software required.

Why CBFEM?

Traditional connection design relies on simplified analytical models that can miss interaction effects between components. CBFEM builds a shell-element FEA model of every plate and member stub, applies the actual load vector, and checks each component to the AISC limit states directly from stress and strain results.

Recommended First Workflow

1. Define members and verify section properties.
2. Add plates, bolts, welds, stiffeners, or gussets.
3. Confirm member orientations and connection eccentricities.
4. Apply forces and moments from the structural model or project calculations.
5. Run CBFEM and review mesh quality warnings.
6. Review AISC check utilization, stress contours, deformed shape, and governing components.
7. Modify geometry and repeat until checks pass with appropriate engineering margin.
8. Generate the final report and save with the issued calculation package.

Requirement	Minimum	Recommended
OS	Windows 10 (64-bit)	Windows 11
CPU	4-core	8-core
RAM	8 GB	16 GB
GPU	OpenGL 3.3 compatible	Dedicated GPU, 4 GB VRAM
Storage	1 GB free	5 GB
Display	1920 × 1080	2560 × 1440

OpenGL 3.3 is required for the 3D viewport. Most GPUs manufactured after 2012 support it. Integrated graphics (Intel HD/UHD, AMD APU) are supported at reduced performance.

Installation

1. Download ILX-Connections-Setup.exe from the ILX Studio website.
2. Run the installer. A Start Menu entry is registered.
3. On first launch, sign in with your ILX Studio account credentials to activate your seat.

Seat Management

Your seat is tied to your ILX Studio account. Sign in on one machine at a time. Sign out via File → Account → Sign Out to release your seat for use on another machine.

Updates

File → Check for Updates — updates are cryptographically signed and verified before installation.

Creating a New Connection Model

1. Click New Connection on the Start page, or press Ctrl+N.
2. A blank 3D workspace opens with the default coordinate system (X = right, Y = up, Z = toward viewer).
3. Add the primary member: Members → Add Column.
4. Add the secondary member: Members → Add Beam.
5. Add the connection element: Connections → Add Plate / Bolts / Welds.
6. Apply loads: Loads → Applied Forces.
7. Run: Analysis → Run CBFEM.

Opening an Existing Project

Ctrl+O or drag a .ilxc project file onto the application. ILX Structures reaction files (.ilxr) can also be opened — loads are imported directly.

Ribbon Tabs

Tab	Contents
Home	New, open, save, undo/redo
Members	Add/edit column, beam, brace members
Connections	Add plates, bolts, welds, gussets, stiffeners
Loads	Applied forces and moments at each member end
Analysis	Run CBFEM, run self-test, view mesh
Results	AISC check tables, stress contours, deformation
Render	Photorealistic PBR render settings and export
Report	Generate PDF, preview
Settings	Units, materials, section catalog, display

3D Viewport

The central viewport uses an orbit camera — click and drag to orbit, middle-click drag to pan, scroll wheel to zoom. The NavCube in the upper-right lets you snap to standard views (top, front, right, isometric) with a single click.

Properties Panel

Selecting any element in the viewport opens its properties in the right-side panel. All properties can be edited directly; the viewport updates in real time.

ILX Connection uses a parametric connection model — define geometry by setting parameters and the model updates automatically. No manual geometry drawing required.

Connection Types Supported

Connection Type	Notes
Shear tab (single plate)	Simple shear, standard and extended
Double-angle	Bolted or welded to web
End plate (flush and extended)	Moment connection; 4-bolt and 8-bolt patterns
Flange plate	Moment connection with welded flange plates
Gusset plate (brace)	Concentric and eccentric bracing
Column base plate	With anchor rods; axial + moment + shear
Seated beam connection	Clip angle or seat plate
Splice (beam or column)	Bolted or welded

Adding a W-Shape Member

1. Go to Members → Add Column (or Add Beam).
2. Click the Section field to open the Shape Selector.
3. Type a section name (e.g. W14x99) or browse by depth and weight range.
4. Set Material: A992 (Fy = 50 ksi) is the default for hot-rolled W-shapes.
5. Set Orientation: rotation about the member axis, in degrees.

Material Properties (Default A992)

Property	Default	Notes
Fy	50 ksi	Minimum yield strength
Fu	65 ksi	Minimum tensile strength
E	29,000 ksi	Modulus of elasticity
G	11,200 ksi	Shear modulus

Custom materials can be defined in Settings → Materials. The full AISC shapes database may require an appropriate license; custom shapes can be entered manually.

Plates

Add plates via Connections → Add Plate. Specify dimensions, material (A36 default, Fy = 36 ksi), position relative to the primary member, and attachment method (bolted, welded, or both). Plates are modeled as MITC4 shell elements in the CBFEM mesh.

Bolt Groups

Add bolt groups via Connections → Add Bolt Group. Specify bolt diameter (¾" – 1¼"), grade (A325 or A490), thread condition (X or N), hole type (STD, OVS, SSLT, LSLT), row × column pattern with pitch and gauge, and pretension level (snug-tight or fully pretensioned).

Welds

Add welds via Connections → Add Weld. Choose fillet or CJP (complete joint penetration) type, electrode (E70XX default, Fu = 70 ksi), weld size, and select the plate edges to weld in the viewport.

How CBFEM Works

Clicking Analysis → Run CBFEM meshes each plate and member stub as MITC4 shell elements, assembles the global stiffness matrix, applies the specified load vector, solves the linear static problem (with optional GMNA for buckling-sensitive connections), extracts stresses and strains, then evaluates AISC 360-16 Chapter J checks.

Solve Time

Most connections solve in under 10 seconds. Large gusset plates or heavily bolted connections with fine meshes may take 30–60 seconds.

Self-Test

Analysis → Run Self-Test runs benchmark problems with known analytical solutions and verifies the FEA engine is within tolerance. Run this after installation and after any update.

The Results tab shows a table of all AISC 360-16 limit-state checks. Each row includes demand, capacity (φRn or Rn/Ω), utilization (must be ≤ 1.0), status (✓/×), and the AISC clause reference.

Checks Performed

Limit State	AISC 360-16
Bolt shear	J3.6
Bolt bearing on plate	J3.10
Bolt bearing on member web/flange	J3.10
Bolt slip (slip-critical)	J3.8
Weld shear — fillet welds	J2.4
Weld fusion — CJP welds	J2.1
Plate gross-section yielding	J4.1
Plate net-section rupture	J4.1
Block shear rupture	J4.3
Local buckling — plate slenderness	—
Column web local yielding and crippling	J10.2, J10.3
Column flange bending (moment connections)	J10.6

LRFD vs. ASD

Switch between LRFD and ASD in Settings → Design Method. The check table and report update immediately.

Navigation

Action	Control
Orbit	Left-click drag
Pan	Middle-click drag
Zoom	Scroll wheel
Snap to view	Click a NavCube face
Fit all	F or double-click NavCube
Select element	Left-click
Multi-select	Shift + left-click

Display Modes

• Wireframe — edges only, fastest
• Solid shaded — flat shading, opaque
• Solid + edges — shaded with edges highlighted
• Stress contours — von Mises or principal stress (available after solving)
• Deformed shape — amplified deformation overlay (scale factor adjustable)

ILX Connection includes a PBR (Physically Based Rendering) render path built on the same OpenGL viewport — no separate render engine or export required. Enable with Render → Enable PBR Render.

Render Presets

Preset	Description
Shop floor	Industrial lighting, concrete floor
White studio	Neutral white environment for report images
Outdoor	Sky HDR, directional sun
Custom	Load your own HDR environment map

Exporting a Render

Render → Export Image — PNG or JPEG, up to 4K resolution. Use for report cover images, presentation slides, shop drawing illustrations, and RFI attachments.

Report → Generate PDF produces a multi-section PDF: cover page, connection summary, input summary, AISC check table (with full derivation and substituted values), FEA result images, and the PE-seal block — activated only when all checks pass.

Report Settings

Settings → Report — configure firm name, engineer name, logo (PNG ≤ 300 × 150 px), design method (LRFD/ASD), and whether to include FEA stress contour images.

Setting	Location	Options
Units	Settings → Units	US Customary / SI
Design method	Settings → Design Method	LRFD / ASD
Theme	Settings → Display → Theme	Dark / Light / High-Contrast
Section catalog	Settings → Section Catalog	Built-in starter / AISC full
Default bolt grade	Settings → Defaults → Bolts	A325 / A490
Default electrode	Settings → Defaults → Welds	E70XX / E80XX
Mesh density	Settings → Analysis → Mesh	Coarse / Normal / Fine / Custom
Autosave	Settings → Files	Interval in minutes

Viewport Shows a Black Screen

Verify your GPU supports OpenGL 3.3. Update graphics drivers from the GPU manufacturer. As a fallback, enable Settings → Display → Software Renderer.

Analysis Fails with “Stiffness Matrix Singular”

A component is not connected to any other. Check that all plates are bolted or welded to at least one member or plate.

“Section Not Found in Catalog”

Enter dimensions manually: Members → Properties → Section → Manual Entry. The built-in starter catalog covers the most common W-shapes.

Report PDF is Blank or Corrupt

Ensure at least 200 MB of free space in your %TEMP% folder. Try pointing the output to a local folder: File → Settings → Report → Output Directory.

Self-Test Fails

Contact support@ilxstudio.com with the self-test log from %LOCALAPPDATA%\ILX Studio\Connections\Logs\selftest.log.

A. Manual Conventions

Convention	Meaning
Bold text	Button, ribbon tab, menu item, panel name, or UI label
Monospace	Command, file extension, keyboard shortcut, path, or literal value
File → Open	Menu path or ribbon navigation sequence
✓ / ✗ / ⚠	Pass, fail, and warning status indicators

B. File Management

Store active projects in a version-controlled or backed-up project folder. Use clear filenames with project number, discipline, revision, and date. Keep exported PDFs separate from editable native project files (.ilxc).

C. Validation & Professional Review

ILX Connection assists qualified users; it does not replace professional judgment. The responsible engineer must verify all inputs, load paths, boundary conditions, connection geometry, and final reports before issuance.

D. Accessibility

Supports Dark, Light, and High-Contrast themes. Increase UI text scale in Settings → Display. Use keyboard shortcuts for repeated commands.

E. Support & Logs

Include product name and version, Windows version, project file (if permitted), steps to reproduce, screenshots, and log files from %LOCALAPPDATA%\ILX Studio\Connections\Logs\ when contacting support@ilxstudio.com.

F. Glossary

Term	Meaning
CBFEM	Component-Based Finite Element Method — shell FEA of connection components with AISC limit-state checks.
DCR	Demand-to-Capacity Ratio; values above 1.0 indicate failure for strength checks.
LRFD	Load and Resistance Factor Design — strength design with load and resistance factors (φ).
ASD	Allowable Stress Design — service-level design with safety factors (Ω).
MITC4	Mixed Interpolation of Tensorial Components, 4-node — the shell element formulation used for CBFEM meshing.

G. Revision History

Version	Date	Notes
1.0	2026	Initial manual draft.
1.1	2026	Expanded professional-use guidance, QA, accessibility, and glossary content.

H. Steel Connection Review Checklist

• Member sizes, materials, orientations, and connection geometry.
• Load source, sign convention, and whether loads are ASD or LRFD.
• Bolt grade, diameter, hole type, thread condition, pretension, and slip-critical assumptions.
• Weld size, electrode, effective length, and access for fabrication/inspection.
• Plate thickness, edge distances, spacing, and constructability.
• Mesh warnings, stress concentrations, and governing AISC checks.
• Report includes all required load combinations and governing components.