Open Source steel design assistants — hot-rolled AISC 360/341 and cold-formed AISI S100/S240/S400.
New module to upload your existing steel building design then run pushover, nonlinear response history analysis (NLRHA) and a full GMNIA Direct Design Method (DDM) analysis for free, no LLM subscription and no specification documents required. Watch the installation video.
// steltic latest updatesOctober has seen updates and bug fixes to both the USA and India versions of Steltic, make sure to update your modules in your Hub!
// steltic on your machineSteltic assistants are free and open source (MIT). Run them on your own machine, with your own buildings and no limits: github.com/Steltic/steltic (AISC) · github.com/Steltic/steltic_cfs (CFS) · github.com/Steltic/steltic_nonlinear (Non Linear).
// steltic on your machine in a HubSteltic Hub brings the Steltic assistants into a single Hub, a one-stop-shop for assisting your structural steel design tasks: github.com/Steltic/steltic_hub. Watch the installation video.
// steltic on a virtual machine with Grok BotSteltic assistants can be setup on a virtual machine with Grok Bot. Prompts and video.
// steltic Indian standards version →The Indian Standards version of the Steltic Hub and all the design assistants (IS 800, IS 801, IS 1893), with 39 worked Indian designs (five of them PEB sheds) and 24 nonlinear runs. Go to Steltic India.
Paste these three lines into a terminal. The first run fetches everything it needs (uv, Python and the hub) and then opens the Hub window. Nothing to install beforehand.
git clone https://github.com/Steltic/steltic_hub cd steltic_hub windows\Steltic.bat
Needs git. Your data is kept in %LOCALAPPDATA%\Steltic.
Steltic Hub brings the various Steltic modules into a single Hub, a one-stop-shop for assisting your structural steel design tasks. Design, Opensees analysis and grounding in your copies of the latest technical specifications.
Choose a building, then drag to orbit, scroll to zoom, and use the module strip to move between the Steltic design and the three nonlinear analyses.
Structural steel buildings (currently up to 20 stories) designed to AISC 360 and 341 (and 358 where appropriate): OpenSees analysis embedded in the session, ASCE 7 loads, all members and connections designed, lateral stability checked.
GitHub ↗ · Example report ↗ · Example 3D model ↗
Every example brief that ships with Steltic, re-designed end to end by Claude Opus 5.5 in October 2026 on the corrected engine (US-practice review: AISC 360/341/358-22, ASCE 7-22).
Cold-formed steel buildings designed to AISI S100-16 (R2020) w/S2,S3, S240-20 and S400-20 with ASCE 7-22 loads: wall-path buildings (WSP, steel-sheet, strap-braced and gypsum shear walls, Type II segments, podium and mixed systems, up to 8 stories) and portal-frame buildings, with stud/track/chord, connection, anchorage and drift design in every package.
GitHub ↗ · Example report ↗ · Example 3D model ↗
Every in-scope example brief that ships with Steltic CFS, re-designed end to end by Claude Opus 5.5 in October 2026 on the corrected engine (AISI S100-16 w/S2-20, S240-20, S400-20, ASCE 7-22).
Introducing Steltic Non Linear. It takes steel buildings designed by Steltic then undertakes: Pushover (ASCE 41-23 and AISC 342-22), NLRHA (eleven real earthquakes per ASCE 7-22 Chapter 16) and Direct Design Method analyses (a GMNIA fibre model with imperfections and residual stresses, every load combination scaled to collapse).
GitHub ↗ · Example library ↓ · 3D viewer ↑
Steltic designs of the HR test buildings, each run through all three analyses with the shipped defaults: fibre pushover, eleven-record NLRHA and the DDM sweep of every load combination. The verdicts are shown as computed, including the ones that fail.
| Building | Pushover Ω (X / Y) | NLRHA (ASCE 7-22 16.4) | DDM φsλu |
|---|---|---|---|
| Loading results… | |||
Ω = peak pushover base shear / design base shear. NLRHA: the suite verdict, unacceptable responses, the mean of the record peak story drifts against the limit and, where it governs, the force-controlled column check (16.4.2.1). DDM: the governing system factor × load factor at collapse (≥ 1.00 passes), with the number of load combinations that pass; INCOMPLETE where none fails but one could not be evaluated. Two of the eighteen HR test buildings (plate shear wall systems) are outside version 1 and are not shown. The STMF building (Ex28) is not evaluated: pushover and NLRHA do not support truss moment frames, and its design model represents each truss by a rolled-beam stand-in, so a DDM of that model would not check the trusses.
Steltic is a family of free, open-source structural design assistants for engineers: an agentic harnessi that drives an AI LLM through the full steel design workflow — hot-rolled steel (AISC 360/341), cold-formed steel (AISI S100/S240/S400), and nonlinear checks on finished designs (pushover, NLRHA, DDM). The assistants live on GitHub.
Steltic has no LLM of its own — it is an LLM harness that guides your LLM through the structural design workflow but generates no engineering content of its own; every model, calculation, figure, and report is produced by your LLM. You simply input your API URL and API key at the beginning of your session (you pay the LLM costs).
The harness is designed to lead the LLM through a first pass, then enters a traditional "chat" format, wherein the building is now in context and the user can ask the LLM to make any changes.
Quick Start — 61 worked example buildings ship across the HR and CFS assistants (36 AISC + 25 CFS), and 15 of the HR test buildings have full nonlinear results (pushover, NLRHA and DDM). Install locally and design your own, or run the shipped examples.
Four Grok Bots, two prompts each. Copy from the slider — full files on github.com/Steltic/steltic_grokbot.
If you want to add all Steltic assistants to your Grok Bot, create one bot called Admin (for example), then give it this single prompt:
You are the site Admin for a new Steltic Grok Bot install. Create four teammate Grok Bots (use CreateAgent), then message each one its setup prompts so they bootstrap themselves. Do not design buildings yourself. Create these bots (names exact): 1. Query file manager 2. HR Steel App 3. CFS Steel App 4. Steltic Nonlinear Then SendToAgent each bot the messages below, in order 1→4. For each bot: first send Prompt 1, wait until they confirm the skill is loaded (or send both in one message clearly labeled Prompt 1 then Prompt 2). Report back when all four have been created and messaged. === Query file manager — Prompt 1 === Load skills/Skill_query_file_manager_PACKAGED.md from https://github.com/Steltic/steltic_grokbot as a skill. === Query file manager — Prompt 2 === Clone https://github.com/Steltic/steltic_grokbot onto your computer. Copy scripts/ to /workspace/engineering_rag/scripts and engineering_rag_phase2/ into /workspace/engineering_rag/. Create a Python venv at /workspace/engineering_rag/.venv, install Docling 2.123.1 (do not upgrade it without revalidation), and set TESSDATA_PREFIX=/usr/share/tesseract-ocr/5/tessdata/ and DOCLING_DEVICE=cpu. Tell me when that bootstrap is done. (After Prompt 2, remind the user: Supply the specs — place your own licensed PDFs in the working-folder standards/. Follow the first-run sequence in the Query file manager skill. The Bot will run retrieval checks on the converted specifications, revise as needed, then report when they are ready for design. Also convert ASCE/SEI 41-23 and ANSI/AISC 342-22 with stems ASCE_41_23 and AISC_342_22 for Steltic Nonlinear.) === HR Steel App — Prompt 1 === Load skills/Skill_querying_PACKAGED.md from https://github.com/Steltic/steltic_grokbot as a skill. === HR Steel App — Prompt 2 === Clone https://github.com/Steltic/steltic onto your computer. Install it per the README (Python 3.12, pip install -e . — openseespy needs native libs, install those too). Verify by running the app with model MOCK and confirming a design package appears. Then read contract/AGENT_START.md: for future design tasks you will follow that contract yourself — write cfg.py, run the engine via python in your terminal, fill the calc package, run consistency.check, and deliver report.html + viewer_3d.html. Let me know after you complete the MOCK tests, then Run the first example building end to end that way. === CFS Steel App — Prompt 1 === Load skills/Skill_querying_PACKAGED.md from https://github.com/Steltic/steltic_grokbot as a skill (same file as HR). === CFS Steel App — Prompt 2 === Clone https://github.com/Steltic/steltic_cfs onto your computer. Install it per the README (Python 3.12, pip install -e . — openseespy needs native libs, install those too). Verify by running the app with model MOCK and confirming a design package appears. Then read contract/AGENT_START.md and contract/CFS_REFERENCE.md: for future design tasks you will follow that contract yourself — write cfg.py, run the engine via python in your terminal, fill the calc package, run consistency.check, and deliver report.html + viewer_3d.html. Let me know after you complete the MOCK tests, then Run the first example building end to end that way. === Steltic Nonlinear — Prompt 1 === Load two skills from https://github.com/Steltic/steltic_grokbot: skills/Skill_querying_PACKAGED.md and skills/Skill_SNL_PACKAGED.md. === Steltic Nonlinear — Prompt 2 === Clone https://github.com/Steltic/steltic_nonlinear onto your computer, next to the Steltic (HR) repository (the DDM step needs its steel_engine folder). Create a Python 3.12 venv (openseespy only ships wheels for 3.10–3.12) and pip install -e . in the repo. Set STELTIC_ENGINE_DIR to the absolute path of steltic/steel_engine. Verify the install on the packaged example (no retrieval needed): python -m snl inspect examples/Ex22_SMF python -m snl report examples/Ex22_SMF python -m pytest tests -q python -m snl run examples/Ex22_SMF --only pushover --params examples/Ex22_SMF/hinge_params_ex22_aisc342.json Open examples/Ex22_SMF/steltic_viewer_bundle.html and flip through the four viewers. From now on, for every job, follow skills/Skill_SNL_PACKAGED.md: inspect the HR package zip; send ONE wave-1 retrieval plan to Query file manager; fill the job hinge_params.json from excerpts; run python -m snl run <zip> --params <job>_hinge_params.json --steltic-engine $STELTIC_ENGINE_DIR --parallel 2; judge pushover, NLRHA and DDM; deliver the job folder with four_analyses.html, steltic_viewer_bundle.html, narrative, retrieval_log.md and open items. Product defaults are in docs/PRODUCT_DEFAULTS.md (NLRHA ModIMK→PZ×1→fibre; dual-gate; CFS DDM Tier 2; HR DDM/NSP fibre+mesh 10%). Report back: example Omega in X and Y, BSE-2N targets, viewer bundle confirmed.
Steltic has been internally tested thoroughly with Claude Fable 5 and ChatGPT 5.6 Sol. These frontier models perform exceptionally well and typically complete the full design with no human-in-the-loop. Notably, ChatGPT 5.6 Sol systematically designs quite conservatively in the initial no human-in-the-loop run (this simply requires the user to prompt an optimization run following the first completion). Limited testing has shown Opus 4.8 to also be very good. Without doubt, Fable 5 is the best choice for excellent results.
Open-weight models — Zai GLM 5.2 and DeepSeek 4 Pro have been extensively tested; however they perform substantially less well, sometimes forget the agent instructions, sometimes "spin their wheels" on unimportant issues, and generally require substantial human-in-the-loop support.
Other LLMs — any LLM for which a user has an API key can be used in the harness; however, as with all AI products, less intelligent models will give less intelligent results. Nonetheless, you can test any model you wish.
Your LLM is fully grounded to the latest specifications and design procedures. The AISC assistant has access to RAG vector databases of AISC 360, 341 and 358 (2022), an examples database of OpenSees models, two databases of the OpenSees documentation, and the AISC Steel Construction Manual Design Examples of 168 design examples (V16.0). The CFS assistant is grounded the same way to AISI S100-16 (R2020) w/S2,S3, S240-20 and S400-20. Steltic Nonlinear retrieves ASCE/SEI 41-23, ANSI/AISC 342-22, ASCE 7 Chapter 16 and related clauses through Query file manager. These corpora are built from your own licensed PDFs (or hosted privately when you run grounded servers), and Steltic directs your LLM to query them to ground its calculations.
Running it yourself — input is anything you can describe. In the open-source versions you write the brief in text (stories, bays and spacings, loads, seismic, system), attach drawings or PDFs if your model reads images, and keep working with the agent afterwards. After the initial run your building is in context, so you can change the geometry, change the seismic LFRS, optimise the member sizes based on the drift, etc. Simply chat with your LLM to investigate any alternative designs.
Outputs. A structural engineering report (report.html) written
to the level a senior engineer needs for review, the analysis model files, an interactive 3D viewer of that
model, the conversation history and the reasoning trace where your model exposes one. The 3D viewer is how
you verify the modelling. In the open-source
versions you can modify the report parameters to include anything you think is useful for reviewing
purposes. You get consistent data output for every building, every design, every time.