ILX Structures combines a second-order frame solver with code-checked member design so you can size beams, columns, braces, and complete lateral systems in one model — and produce a transparent, code-ready calculation package the reviewer can follow line by line.
ILX Structures was built around the day-to-day reality of building design: most steel members are governed by a handful of limit states, but getting from a framing layout to a defensible design means generating loads, building credible load combinations, running a stability-aware analysis, and then documenting every check. ILX Structures connects those steps so the analysis model and the design checks share the same geometry, section properties, and material data — no re-keying between an analysis package and a separate spreadsheet.
The result is a workflow where you model the frame once, assign loads and combinations, solve, and review utilization ratios member-by-member. Every governing equation is shown with the clause it comes from, the input values, and the resulting capacity — so the engineer of record retains full judgment and the checker never has to reverse-engineer a black box.
Tension, compression, flexure, shear, and combined axial-plus-bending checks for the full member list, with governing limit state and utilization reported for each.
2D and 3D first- and second-order elastic analysis of moment frames, braced frames, trusses, and gravity systems.
Stiffness reduction, notional loads, and P-Δ / P-δ effects applied automatically so stability is built into the analysis, not bolted on with K-factors.
Dead, live, roof live, snow, wind, and seismic load patterns derived from ASCE 7, with automatic strength and service load combinations.
Rolled W, S, M, HP shapes, HSS (round and rectangular), pipe, channels, angles, tees, and user-defined built-up plate sections.
Least-weight section suggestions within a designer-controlled shape group, respecting depth, availability, and serviceability limits.
Deflection and drift checks against project-defined limits, including live-load, total-load, and inter-story drift criteria.
Step-by-step calculation output with clause references, free-body results, and a summary table — export-ready for the project record.
Change a section or a load and re-solve in place; utilization ratios update so you can converge a design quickly.
ILX Structures implements published, consensus design provisions. The development effort included building and validating each limit state against worked examples and hand calculations so that results are traceable to a specific code clause. The core references are summarized below.
| Domain | Basis | What it governs |
|---|---|---|
| Steel design | AISC 360 — Specification for Structural Steel Buildings (LRFD & ASD) | Tension (Ch. D), compression (Ch. E), flexure (Ch. F), shear (Ch. G), combined forces (Ch. H), member properties (Ch. B) |
| Stability | AISC 360 stability provisions — Direct Analysis Method | Second-order effects, stiffness reduction, notional loads, effective length treatment |
| Connections (interface) | AISC 360 Ch. J | End reactions and design forces handed off to ILX Connection |
| Loads | ASCE 7 — Minimum Design Loads | Dead, live, snow, wind, and seismic loads; strength and allowable-stress load combinations |
| Adoption | International Building Code (IBC) | Reference standard adoption, risk categories, and design parameters |
| Material | Published structural steel grades | Yield and tensile strength, modulus, and section property databases |
Standards are referenced by their issuing organizations for interoperability. ILX Studio is an independent software developer and is not affiliated with, nor endorsed by, any standards body.
1. Model. Lay out framing with nodes, members, supports, and releases; assign sections and materials from the library.
2. Load. Apply gravity, lateral, and pattern loads, then auto-build the governing strength and service combinations.
3. Solve. Run the second-order direct-analysis solution; review reactions, diagrams, and displaced shape.
4. Design. Check every member, see governing limit states and utilization, and optimize sections in place.
5. Document. Generate the calculation package and hand member end forces directly to ILX Connection.
Member design follows the AISC Specification for Structural Steel Buildings (AISC 360), supporting both LRFD and ASD, with loads and load combinations from ASCE 7 and the IBC.
Yes. ILX Structures runs a second-order analysis capturing P-Δ and P-δ effects and implements the Direct Analysis Method — applying stiffness reduction and notional loads — so stability is accounted for directly rather than through assumed effective-length factors.
Rolled W, S, M, HP shapes, HSS and pipe, channels, single and double angles, tees, and user-defined built-up plate sections, across common published structural steel grades.
Every check is presented with its governing clause, input values, intermediate quantities, and resulting capacity, so the engineer of record can review and stamp a transparent calculation set. ILX Studio provides the tool; professional judgment and responsible charge remain with the licensed engineer.
Member end forces pass directly into ILX Connection for connection design, and calculation output can be assembled into a sealed project package with ILX PDF.
ILX Structures is a structural analysis and design application for Windows. It builds node/member/plate models, applies load cases and ASCE 7-22 load combinations, solves them with a finite-element engine, and checks members to AISC 360 (steel) and ACI 318 (concrete) — with code-cited PDF reports. Multiple models can be open simultaneously as document tabs.
ILX Structures main window — 2-story moment frame in the 3D viewport, member list on the left, Results panel on the right with envelope moment diagrams.
img/structures_main_interface.png — screenshot coming soon
| Requirement | Minimum | Recommended |
|---|---|---|
| OS | Windows 10 (64-bit) | Windows 11 |
| CPU | 4-core | 8-core |
| RAM | 8 GB | 16 GB |
| GPU | OpenGL 3.3 | Dedicated GPU |
| Storage | 1 GB free | 5 GB |
| Display | 1920 × 1080 | 2560 × 1440 |
ILX-Structures-Setup.exe from the ILX Studio website..ilxs project file association are registered.Your seat is managed through license.ilxstudio.com. One machine at a time per seat. Sign out via File → Account → Sign Out to free the seat. Updates are cryptographically signed and verified before applying.
Ctrl+N or New Model on the Start page. A blank model opens with the default coordinate system: X = horizontal, Y = vertical, Z = out-of-plane.
Ctrl+O or drag a .ilxs file onto the application. Multiple models open as tabs — each with its own independent analysis state.
Ctrl+S saves in the native .ilxs format (atomic JSON — crash-safe). File → Export → DXF exports the structural geometry as a CAD underlay.
| Tab | Contents |
|---|---|
| Home | New, open, save, undo/redo, clipboard |
| Model | Add nodes, members, plates, supports |
| Loads | Load cases, load assignment, combinations |
| Analysis | Run static, run P-Δ, check mesh |
| Design | Steel checks, concrete checks, optimize |
| Results | Diagrams, contours, reactions, report |
| View | Display filters, viewport controls, render settings |
| Manage | Project settings, section catalog, materials |
The left dock shows the model hierarchy: Nodes, Members, Plates, Supports, Load Cases, Combinations. Click any item to select it; the viewport highlights it and the Properties panel opens on the right.
The workflow: place nodes → connect members → assign sections → apply supports → define load cases → assign loads → set combinations → run analysis → run design checks → generate report.
Model → Add Node — click in the viewport or type coordinates (X, Y, Z). Use the grid snap and coordinate-entry toolbar to place nodes accurately.
Model → Add Member — click a start node, then an end node. Assign its section before running analysis.
Global: X = horizontal (East), Y = vertical (Up), Z = out-of-plane (toward viewer). Each member has a local coordinate system (x along the member axis) — displayed by toggling View → Member Axes.
3D frame model with load arrows showing gravity loads on beams, lateral wind loads on columns, and foundation support symbols.
img/structures_model_loads.png — screenshot coming soon
| Type | Description | Typical Use |
|---|---|---|
| Beam | Flexure + shear, end releases optional | Floor beams, roof beams |
| Column | Axial + biaxial bending | Vertical members |
| Brace | Axial only (pin-pin releases) | Diagonal bracing |
| General | User-defined releases | Custom framing |
Select members → Properties → Section: Steel W-shape, HSS, pipe, angle, channel, WT; Concrete rectangular or circular; Custom (A, Ix, Iy, J). By default, members are moment-connected at both ends. To create a pin, set Properties → Releases → Pin.
| Preset | Translations Constrained | Rotations Constrained |
|---|---|---|
| Fixed | All (Tx, Ty, Tz) | All (Rx, Ry, Rz) |
| Pin | All | None |
| Roller (X free) | Ty, Tz | None |
| Roller (Z free) | Tx, Ty | None |
Right-click any node → Assign Support Preset to quickly apply standard support conditions. For soil-supported structures, assign translational spring stiffness (kip/in) for mat foundations and grade beams.
| Category | ASCE 7 Symbol | Examples |
|---|---|---|
| Dead | D | Self-weight, superimposed dead |
| Live | L | Floor live, reducible live |
| Roof Live | Lr | Roof live load |
| Snow | S | Ground snow, drift |
| Wind | W | ASCE 7 wind pressure |
| Seismic | E | ASCE 7 seismic |
Assign point loads, uniform/trapezoidal distributed loads, area loads on plates, and temperature loads via the Loads ribbon. Self-weight is a per-case toggle — the engine computes it from section properties and material density.
Loads → Combinations → Generate ASCE 7 automatically creates governing strength and serviceability combinations from ASCE 7-22 Tables 2.3.1 (LRFD) and 2.4.1 (ASD) using your defined load cases.
Analysis → Run Static — solves Ku = F for all load cases simultaneously. Results are available for each case and for all combinations (enveloped automatically).
Analysis → Run P-Δ — iterative second-order analysis accounting for the destabilizing effect of gravity loads on laterally displaced columns. Required by AISC 360 App. 8 for moment frame design. The Newton-Raphson solver typically converges in 3–5 iterations for sway-sensitive frames.
Results view showing a moment envelope diagram overlaid on a 2-story frame, with the critical beam highlighted and the governing load combination in the Results panel.
img/structures_moment_diagram.png — screenshot coming soon
| Diagram | Description |
|---|---|
| Axial force | N (compression/tension) along member |
| Shear (major/minor) | Vy / Vz — strong/weak axis shear |
| Moment (major/minor) | Mx / My — strong/weak axis moment |
| Torsion | T — torsional moment |
| Deflection | Lateral and vertical deformation |
Toggle Envelope in the Results ribbon to show max/min values across all load combinations simultaneously. Results → Reactions shows support reactions for each case — export to CSV for foundation design.
Design → Serviceability checks: live load L/360, total load L/240, lateral drift H/500 (wind) / H/400 (seismic). All limits configurable.
Design → Steel Design runs AISC 360-16 member design for all steel members after analysis is complete.
| Check | AISC Reference |
|---|---|
| Tension yielding | D2.1 |
| Tension rupture | D2.2 |
| Compression — flexural buckling | E3 |
| Compression — flexural-torsional buckling | E4 |
| Bending — compact section | F2 |
| Bending — non-compact / LTB | F3, F4, F5 |
| Shear | G2 |
| Combined (axial + bending) | H1-1 interaction |
| Lateral-torsional buckling | F2.2 |
Assign effective length factors (Kx, Ky) and unbraced length Lb in member properties. Switch between LRFD and ASD in Manage → Design Method.
Generated report page showing the steel design check table with member IDs, sections, utilization ratios, governing checks, AISC clause references, and a green all-pass banner.
img/structures_report_design_table.png — screenshot coming soon
Design → Concrete Design runs ACI 318-19 demand-capacity checks for concrete members as part of the overall building model: Flexural DCR (Mu ÷ φMn), Shear DCR (Vu ÷ φVn), Axial DCR (Pu ÷ φPn).
For detailed concrete member design (full reinforcement layout, bar spacing, detailing, seal-gated reports), the recommended workflow is: run ILX Structures for system reactions and forces → export to ILX Concrete for the detailed member design.
Results → Generate Report produces a PDF with: cover page, model summary, geometry tables, load tables, analysis summary, member forces envelope table, support reactions, steel design check table (with AISC clause citations and pass/fail), governing combinations, and the PE-seal block (when all checks pass and analysis is current).
File → Project Settings → Report: firm name, logo, PE name, design method label, unit display.
ILX Structures supports multiple models open simultaneously as document tabs. Each model is independent; analysis, results, and design checks belong to the tab they were run in.
Open two tabs side by side: View → Split View → Vertical / Horizontal. Both viewports are interactive — useful for comparing design alternatives.
.ilxr reaction file..ilxr file.Split View mode with two tabs side by side — braced frame vs. unbraced frame alternative, comparing deflected shapes under lateral load.
img/structures_split_view.png — screenshot coming soon
The model is a mechanism. Check that at least one node is fully fixed in each global direction and that no isolated member group lacks a support connection. Use Model → Check → Mechanism Finder.
Gravity load is too large relative to lateral stiffness. Check member sizes and try Analysis → Run Linear Buckling. Increase max iteration count in Analysis → Settings → P-Δ Iterations (default 50).
Check the section designation spelling in Properties → Section. Custom sections (defined by A, Ix, etc.) are treated as general members without AISC 360 code checks unless assigned to an AISC section family.
Check that loads were assigned to a load case and that the case is included in at least one combination with a non-zero factor.
| Convention | Meaning |
|---|---|
| Bold text | Button, ribbon tab, menu item, panel name, or UI label |
Monospace | Command, file extension, keyboard shortcut, path, or literal value |
| ✓ / ✗ / ⚠ | Pass, fail, and warning status indicators |
Store active projects in a version-controlled folder. Keep exported PDFs separate from editable native project files (.ilxs). Use autosave (configurable in Project Settings).
The responsible engineer must verify model geometry, support conditions, load paths, load combinations, stiffness assumptions, releases, diaphragm modeling, P-Δ settings, and member design parameters before relying on results.
Dark, Light, and High-Contrast themes available. Increase UI text scale in Settings → Display.
Crash logs at %LOCALAPPDATA%\ILX Studio\Structures\Logs\. Contact support@ilxstudio.com with product version, Windows version, project file, and steps to reproduce.
| Term | Meaning |
|---|---|
| DCR | Demand-to-Capacity Ratio; values above 1.0 indicate failure. |
| P-Δ | Second-order analysis accounting for geometric nonlinearity due to lateral displacement. |
| LTB | Lateral-Torsional Buckling — out-of-plane buckling of a beam between lateral bracing points. |
| Lb | Unbraced length — distance between lateral bracing points for LTB checks. |
| Version | Date | Notes |
|---|---|---|
| 1.0 | 2026 | Initial manual draft. |
| 1.1 | 2026 | Expanded professional-use guidance, QA, accessibility, and glossary content. |
Request a demo and we will walk a real model from layout to a finished calculation package.
Request a Demo