CalcSteel is a free, open-access structural engineering platform that combines a 3D CAD editor, Finite Element Method analysis, and automatic code-checking against 41 international design standards — all running 100% in the web browser, with zero installation.
CalcSteel is a web-based structural steel design and analysis platform built for engineers, fabricators, architects, and students. It provides a professional-grade 3D CAD editor for steel frame modeling, a Finite Element Method (FEM) solver for structural analysis, and automatic design verification against international building codes — all accessible through a standard web browser.
The platform was created to solve a fundamental problem in structural engineering: professional-quality structural analysis software has traditionally required expensive licenses (SAP2000, ETABS), complex installations (CYPE 3D, Robot Structural Analysis), or was limited to 2D analysis (Ftool). CalcSteel makes 3D steel frame analysis accessible to anyone with a browser and an internet connection.
The engineering engine supports 41 design standards from over 28 countries, covering hot-rolled steel, cold-formed steel, stainless steel, and aluminum. The profile library includes 1,140+ profiles from AISC (American), Eurocode (European), NBR (Brazilian), IS (Indian), and BS (British) catalogs. The material database contains 98 pre-defined grades with full mechanical properties.
CalcSteel runs entirely in the browser using WebGL (Three.js) for 3D rendering and communicates with a Python/FastAPI backend for structural analysis. The frontend is built with React, TypeScript, and Tailwind CSS. The solver uses NumPy and SciPy for matrix operations. Models can be exported to IFC (for BIM workflows with Revit and Tekla) and DXF (for AutoCAD).
Everything a structural engineer needs to model, analyze, and detail steel structures — in one browser tab.
Model steel frames in 3D with professional tools: node and bar creation with snap (endpoint, midpoint, perpendicular, grid, axis projection), move, copy, mirror, divide, and rotate. Chain mode for rapid bar input. Double profiles (back-to-back, box configuration). Profile rotation at any angle.
Direct Stiffness Method solver for 3D frames with 6 degrees of freedom per node. Handles axial forces, biaxial bending moments, shear forces, and torsion. Self-weight computed automatically from profile geometry and material density. Linear-elastic analysis with scipy.linalg.solve.
8 checks per member: slenderness limits, tension capacity, compression with buckling (Euler, Perry-Robertson), strong-axis flexure with lateral-torsional buckling, weak-axis flexure, shear, flexure-compression interaction (H1-1 AISC, EC3 Method 2), and flexure-tension interaction. Color-coded pass/fail in the 3D view.
Complete catalogs from AISC (W shapes, HSS, angles, pipes), Eurocode (IPE, HEA, HEB, HEM, RHS, SHS, CHS, UPE, UPN, angles), NBR (cold-formed C, U, round bars), IS 808 (ISMB, ISMC, ISA), and BS (UB, UC). Plus 89 architectural thin-wall profiles. Custom profile creation with any dimensions.
AISC 360, NBR 8800, Eurocode 3 (with national annexes for Portugal, Spain, Italy, UK, Germany, France), AS 4100, IS 800, CSA S16, plus regional standards for Ecuador, Colombia, Argentina, Chile, Peru, Mexico, South Africa, New Zealand. Cold-formed: NBR 14762, AISI S100, EN 1993-1-3, AS/NZS 4600. Stainless and aluminum standards.
Truss generator (trapezoidal, parallel-chord, Pratt) with span, height, panels. Warehouse generator (multi-bay portal frames with optional roof trusses, purlins, lattice columns). Lattice column generator. Shed generator. All with real-time SVG preview and independent profile assignment per member group.
Automatic 2D view detection from 3D model. Drawing sheets from A0 to A4 with customizable title block (company, project, designer, checker, date, revision). Auto-layout views with scale. Class-based annotations with dimensions and profile labels. Export to DXF R2010.
Shear tab, clip angle, end plate, and base plate connections. Bolt verification (tension, shear, bearing, combined) for grades 8.8, 10.9, A325, A490. Weld sizing (fillet and CJP). Instantaneous Center of Rotation method for eccentric bolt groups. Auto-detection of connection type from geometry. Bill of materials export.
IFC 2x3 export compatible with Autodesk Revit, Tekla Structures, RSTAB, and BricsCAD. DXF R2010 3D export with ACIS solids. DXF 2D sheet export with viewports and title blocks. PDF profile reports with section properties and verification results. CSV bill of materials.
Full interface translation in English, Brazilian Portuguese, European Portuguese, Spanish, French, Bengali, and Arabic (with RTL support). Locale-prefixed URLs for SEO (/pt/profiles, /es/tools, /fr/examples). All 23 documentation articles translated. Profile catalog and comparison pages in all languages.
Automatic load combination generation per design standard: LRFD for AISC and NBR, partial safety factors for Eurocode, capacity factors for AS 4100. Supports permanent, variable, wind, and seismic load natures. Trapezoidal distributed loads. Envelope analysis across all combinations.
Axial force (N), shear forces (Vy, Vz), bending moments (Mz strong-axis, My weak-axis), and torsion (T) rendered as 3D filled polygons along each bar. 21-point interpolation. Color-coded by type. Maximum value labels. Combined diagrams from superposition. Envelope diagram from all combinations.
CalcSteel supports structural steel design codes from North America, South America, Europe, Asia, Oceania, and Africa. Each standard is implemented with its specific safety philosophy: LRFD (Load and Resistance Factor Design) for American codes, partial safety factors for Eurocodes, and capacity reduction factors for Australian codes.
Comprehensive catalog covering AISC (American), Eurocode (European), NBR (Brazilian), IS (Indian), and BS (British) standards. Each profile includes full geometric dimensions, weight per meter (adjusted by material density), and computed section properties (area, moments of inertia, section moduli, radii of gyration, torsion and warping constants).
Each material includes Young's modulus (E), shear modulus (G), yield strength (fy), ultimate strength (fu), and density. Weight is automatically recalculated when switching from standard steel (7,850 kg/m³) to aluminum (2,700 kg/m³) or stainless steel grades.
CalcSteel uses the Direct Stiffness Method (DSM) to perform 3D frame analysis. Each node has 6 degrees of freedom: 3 translations (u, v, w) and 3 rotations (θx, θy, θz). The element formulation handles axial deformation, biaxial bending, shear deformation, and torsion simultaneously.
The solver assembles the global stiffness matrix [K], applies boundary conditions from supports (with up to 8 preset types: fixed, pinned, roller-X/Y/Z, fix-XY, fix-YZ, fix-XZ), and solves the system [K]{u} = {F} using SciPy's direct solver. Results include nodal displacements, support reactions, and internal forces (N, Vy, Vz, My, Mz, T) at 21 interpolation points along each bar.
Section properties are computed analytically for all 8 profile families: area (A), moments of inertia (Ix, Iy), elastic section moduli (Sx, Sy), plastic section moduli (Zx, Zy), radii of gyration (rx, ry), St. Venant torsion constant (J), and warping constant (Cw). For W sections, fillet radius contributions are included.
Portal frames, multi-bay warehouses, roof trusses, purlins, bracing. Parametric generators create full structures in seconds.
Steel-framed buildings with moment-resisting frames, braced frames, and combined systems. Column-beam connections with shear tabs and end plates.
Trapezoidal, Pratt, and parallel-chord trusses. Lattice columns. Space trusses (coming soon). All with automatic member grouping.
Pedestrian bridges, canopies, mezzanines, equipment platforms. Support for aluminum and stainless steel for corrosion-resistant applications.
Free modeling tier perfect for students learning structural analysis. Visual force diagrams help understand structural behavior. 23 documentation articles with video tutorials.
Multi-norm support (41 standards) for international projects. Export IFC for BIM coordination. Generate 2D sheets with title blocks for engineering deliverables.
CalcSteel vs traditional structural engineering software like SAP2000, CYPE 3D, Robot Structural Analysis, RSTAB, and Tekla.
| Feature | CalcSteel | Traditional Software |
|---|---|---|
| Platform | Web browser (zero install) | Desktop application (Windows/Mac) |
| Price | Free tier + affordable Premium | $3,000–$15,000+/year |
| 3D Steel Frame Analysis | Yes (FEM, 6 DOF/node) | Yes |
| Design Standards | 41 standards, 4 material categories | 5–15 standards typically |
| Profile Library | 1,140+ profiles, 5 catalogs | Varies (500–2,000) |
| Multi-Material | Steel, stainless, aluminum (98 grades) | Usually steel only |
| BIM Export (IFC) | Yes (IFC 2x3) | Yes |
| DXF/CAD Export | Yes (R2010, 2D & 3D) | Yes |
| Languages | 7 (EN, PT, ES, FR, BN, AR) | 2–5 typically |
| Free to Start | Yes, unlimited modeling | No (trial or paid only) |
| Documentation | 23 articles with video tutorials | Varies |
| Parametric Generators | Trusses, warehouses, lattice columns | Limited or none |
CalcSteel includes a comprehensive documentation hub with 23 articles organized in 6 sections, covering every aspect of the software from basic navigation to advanced design code verification.
Introduction, first project setup
Templates, editor settings, display options
Nodes, bars, profiles, tools (move/copy/mirror), parametric generators
Support types, load actions per standard, point/distributed/self-weight loads
FEM solver, diagrams, NBR 8800, NBR 14762, Eurocode 3, AISC 360
2D views, plane groups, drawing sheets, tool reference & shortcuts
Each documentation article includes embedded video clips demonstrating the described workflow. The editor features 34 enhanced tooltips that show a text description after 300ms and an inline video demonstration after 800ms of hovering.
CalcSteel is actively developed. Here's what's coming next.
Regional wind speed maps per country. Automatic pressure distribution on structures based on geometry and terrain. Standards: NBR 6123, ASCE 7, EN 1991-1-4, AS/NZS 1170.2, IS 875 Part 3.
Automatic seismic load generation per country and zone. Equivalent lateral force method. Response spectrum analysis. Standards: ASCE 7, EN 1998-1, NEC-SE-DS, NSR-10, NCH 433, NBR 15421, IS 1893.
Complete weld sizing and verification (fillet, CJP, PJP). Bolt group analysis with slip-critical connections. Base plate design with anchor bolt pullout/breakout per ACI 318. Block shear checks.
Parametric generators for 3D space trusses: flat grid, barrel vault, dome, geodesic. Tubular joint verification per EN 1993-1-8. Ideal for stadium roofs, exhibition halls, airport terminals.
No installation. No credit card. Open the editor and start modeling in seconds. CalcSteel supports 41 design standards, 1,140+ profiles, and 98 materials.