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From Brief to Running Model

Describe the structure and the agent builds it in the ETABS or SAP2000 installed on your machine, live on your screen, with your licenses and your section databases. The connection runs through the Stru AI desktop app: set it up once with Connecting ETABS & SAP2000, then model by conversation. Jobs this page covers:
  • Build a model from a brief: geometry, sections, loads, and combinations from one written description
  • Build from structural drawings: attach the framing plans and schedules and model from them
  • Build from an IFC model: turn a BIM model into an analysis model
  • Build a bridge in SAP2000: the same staged pattern, applied to spans instead of stories
Here the agent builds a braced steel frame from a one-paragraph brief, ticking off its task list as the model grows:
The agent building a braced steel frame live in SAP2000, with the prompt and task list beside the model
This page is the workflow. For prompting patterns, ETABS vs SAP2000 selection, and recovery when a session stalls, see the ETABS & SAP2000 Agents guide.

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Set Up Once

1

Install the desktop app and sign in

The agent drives the software on the machine where it is installed, so start with Install & Sign In on that machine.
2

Wait for the green dot

The Client pill in the app header shows a green dot when the app is connected to your ETABS or SAP2000. Details in Connecting ETABS & SAP2000.
3

Pick your agent

Choose ETABS Agent for buildings or SAP2000 Agent for bridges, trusses, and general structures, from the dropdown in the top-left corner.
The agent dropdown with SAP2000 Agent and ETABS Agent

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Stage the Build

A model built in stages is a model you can check at every step. Give the complete brief up front, then have the agent build one stage at a time: grids and stories, then framing, then loads, then the analysis run. Each stage gets verified before the next builds on it.
1

Give the complete brief

Geometry, sections, materials, code, and units, all in the first message. A complete brief gets a complete model; anything you leave out, the agent has to assume.
Example: model brief
Build a 6-story office building in ETABS. Work in stages and
wait for my go-ahead between stages.

- Units: kip, ft
- Grids: 5 bays @ 30 ft in X, 3 bays @ 28 ft in Y
- Stories: 15 ft ground, 13 ft typical
- System: steel moment frames on the perimeter, W14 columns,
  W24 girders, W16 infill beams
- Materials: A992 steel, 4000 psi concrete on metal deck
- Code: ASCE 7-22 load combinations

Start with grids and stories only.
2

Grids and stories first

Everything else hangs off the grid, so confirm it before any framing exists: “Show me a plan view and an elevation before we continue.” Fixing a grid now takes one message; fixing it under a finished model takes a rebuild.
3

Framing next

Columns, then beams, then walls and slabs, one system per message. After each: a screenshot, a quick scan, then the go-ahead. To change something, say exactly which members: “Change the girders on levels 2 to 4 to W24x76, keep the roof as is.”
4

Then loads

Apply gravity first, then lateral, and ask for a screenshot with load arrows visible to confirm the pattern and direction. If the wind and seismic demands still need deriving, Wind & Seismic Load Calcs covers getting them from your site and code. Before moving on: “List every load case and combination you have not applied yet.”
5

Run it and read it back

Run the analysis, then have the agent walk you through the results in the model: “Walk me through the governing drift: story, combination, and value. Then give me the base reaction totals so I can compare them with my hand tally.” Save with a versioned name: “Save as Office_Building_Demo_v1.EDB.”
One stage per request. “Build the whole building” produces a model you have to reverse-engineer to trust. Staged builds produce a model you watched grow, with a checkpoint at every step.

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Build From Your Drawings

Attach the framing plan and reference it with @ so the agent models from your sheet and your numbers. The Mentions guide covers tagging files already in your project.
Example: model from a plan
@S-201_Level2_Framing.pdf Build levels 1 to 3 in ETABS from this
plan. Use the grid dimensions and member sizes shown on the sheet.
Ask me before assuming anything the sheet does not show.
Work sheet by sheet, the way the set is organized: the framing plan for geometry, the column schedule for sections, the general notes for materials. Referencing the sheet in every request keeps the model traceable to the drawing it came from.

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Build From an IFC Model

When the geometry already exists as a BIM model, have the BIM Agent read the IFC first and turn it into a modeling brief.
Example: IFC to modeling brief
@Office_Building_Demo.ifc List the levels, grid lines, and every
column and beam with its section and material. Format the output
as a modeling brief I can hand to the ETABS Agent.
The BIM Agent opens the model in a viewer beside the chat while it reads the file:
The BIM Agent reading an IFC file with the 3D model viewer open beside the chat
Take the brief it produces into an ETABS or SAP2000 Agent conversation and stage the build as above. You review the brief in between, which is exactly where a geometry error is cheapest to catch.

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A Bridge in SAP2000

The staged pattern carries over: alignment and supports first, then the superstructure, then loads.
Example: bridge brief
Build a 3-span continuous steel plate girder bridge in SAP2000.
Work in stages and confirm each stage with a screenshot.

- Units: kN, m
- Spans: 35 m + 45 m + 35 m
- Cross-section: 4 girders at 3.0 m spacing, 250 mm composite deck
- Supports: bearings at abutments and piers, continuous girders
  over the piers
- Loads come after geometry is confirmed: self-weight,
  superimposed dead 2.5 kPa, then AASHTO HL-93

Start with the girder layout and supports.
Trusses, space frames, and cable systems follow the same rhythm; the SAP2000 examples show briefs for each.

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Verify As You Go

Three habits keep a staged build honest:
  • Screenshot every stage. A plan and an elevation after each stage catches misplaced grids and missing members while they are one message deep.
  • Ask what is missing before the run. “List every load case and combination you have not applied yet” turns the gap between intent and model into a to-do list.
  • Read the numbers back after the run. Have the agent open the saved file and report the governing drift and reaction totals, then compare them against your expectations.
You are the engineer of record: the model that goes forward is the one you have checked, and a staged build gives you a checkpoint trail to check it against. For a deeper verification pass on the finished model, export the results and run Check an Existing Model.

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Next Steps

Connecting ETABS & SAP2000

The Client pill, working folders, and detected versions.

ETABS & SAP2000 Agents

Prompting patterns, examples, and stall recovery.

Check an Existing Model

Export the results and verify them against code limits.

Wind & Seismic Load Calcs

Derive the lateral loads before you apply them.Wind & Seismic Load Calcs
Questions? Email support@stru.ai or book a call.