ETABS & SAP2000 Agents - Stru AI Documentation

Getting Started

The ETABS and SAP2000 agents let you build structural models through conversation. Describe what you want, and the agent creates the model automatically.

Access the Agent

Go to app.stru.ai → Select ETABS Agent or SAP2000 Agent from the top-left dropdown

Write Your Prompt

Describe your structure in the input field:

Create a 3-story steel moment frame. Plan: 60ft x 40ft,
3 bays each direction. Story height: 12ft. Use W14 columns,
W18 beams. Units: kip-ft.

Review the Model

The agent builds the model, shows you screenshots, and provides a summary. Iterate with follow-up prompts to refine.

Pro Tip: Use @ to search building codes while writing prompts. Try @ASCE 7 for wind loads or @ACI 318 for concrete design.

What You’ll See

When you submit a prompt, the agent breaks down the task, executes the modeling steps, and shows you the completed model:

SAP2000 Agent modeling a 4-story eccentric braced frame building

The interface shows:

Left panel: Task breakdown with completed (✓) and in-progress (⚡) steps
Center: Interactive 3D model views from SAP2000/ETABS - click to select elements for modification
Right panel: Agent’s explanation of what was built and validation summary

ETABS vs SAP2000: Which Agent?

ETABS Agent

Choose for:

Buildings (high-rise, concrete frames, shear walls)
Floor diaphragms and vertical load distribution
Building-specific seismic and wind design
Story-based modeling workflows

SAP2000 Agent

Choose for:

Bridges, trusses, space frames
Industrial structures and towers
Long-span systems and stadiums
General-purpose structural analysis

Writing Effective Prompts

The Golden Rule

Either be specific OR explicitly give the agent discretion. Avoid vague prompts.

Create a 4-story building:
- Plan: 120ft x 80ft
- Bays: 4 @ 30ft in X, 4 @ 20ft in Y
- Story heights: 15ft ground, 12ft typical
- Columns: W14x120
- Beams: W21x50
- Units: kip-ft

Key Prompt Elements

Specify Units Upfront

Always include units in your first prompt:✅ “Use kip-ft units for this model…”Prevents unit confusion later.

Break Complex Tasks

For complex structures, work incrementally:

First, create the basic frame geometry.
[Review screenshot]
Now add X-bracing to perimeter frames.
[Review again]
Finally, apply gravity loads.

Be Clear on Directions

Specify load directions clearly:✅ “Apply loads in gravity direction (downward)”✅ “Wind loads in Global Y direction”✅ “Distributed along member length”

Common Use Cases

1. Regular Building Frame

Create a 5-story reinforced concrete frame:
- Plan: 100ft x 75ft
- 5 bays @ 20ft in X, 5 bays @ 15ft in Y
- Story height: 12ft typical
- Columns: 24"x24", Beams: 18"x24"
- Concrete: f'c = 4000 psi
- Apply loads: DL=120psf, LL=60psf

2. Steel Truss Bridge

Create a 100ft Warren truss:
- Span: 100ft, Depth: 12ft, Panel spacing: 10ft
- Top chord: HSS10x10x5/8
- Bottom chord: HSS8x8x1/2
- Web members: HSS6x6x3/8
- Supports: Pin at left, roller at right

3. Adding Lateral System

Add X-bracing to perimeter frames on gridlines A and D.
Use HSS8x8x1/2. Place bracing in bays 1 and 3, all stories.

4. Modifying Existing Model

Option 1: Describe the changes

Change all W14x90 columns on levels 3-5 to W14x120.
Keep levels 1-2 unchanged. Show me a before/after comparison.

Option 2: Select and modify Click to select specific columns in the 3D viewer, then: “Change these selected columns to W14x120”

5. Load Combinations

Apply gravity loads to all beams:
- Dead: 1.2 kip/ft (includes self-weight)
- Live: 0.8 kip/ft

Then create ASCE 7-22 load combinations for gravity design.

Advanced Usage

Study and Recreate Existing Models

The agent can analyze existing models and recreate them with modifications:

Open 'Existing_Building.sdb' and study its geometry, sections,
and loads. Then create a similar model but with:
- 20% taller story heights
- Updated to ASCE 7-22 wind loads
- Member sizes optimized for new loads

Use cases: Modernize old models to new code provisions, create design variations, or standardize legacy projects.

Compare Two Models

Compare different design options:

Compare 'Option_A.sdb' and 'Option_B.sdb':
Total steel weight difference
Drift ratios under lateral loads
Foundation reactions comparison
Cost implications of member size differences

Use cases: Design optimization, value engineering studies, structural system selection, and code compliance verification.

Use Sketches and Floor Plans

Upload drawings to convey information:

I'm attaching a floor plan sketch. Create a 3-story model
based on this layout. Use W14 columns and W18 beams.
Story height: 12ft.

What you can upload: Hand-drawn sketches, PDF floor plans, marked-up elevations, or structural diagrams. The agent interprets dimensions, grid layouts, and structural intent from images.

Parametric Design and Iterations

Rapidly generate design variations:

Create 5 design iterations of this building:

Base case: 4-story, 100ft x 60ft, W14x90 columns
Iterations:
1. Increase to 6 stories, adjust columns accordingly
2. Change bay spacing from 25ft to 30ft
3. Add perimeter braced frames instead of moment frames
4. Use concrete columns instead of steel
5. Optimize member sizes for minimum weight

Save each version and provide weight/cost comparison table.

Powerful for: Early design exploration, code-driven updates, client options, optimization studies, and sensitivity analysis. Example: Beam depth study

Create 3 models with beam depths of 18", 21", and 24".
Keep all other parameters constant. Report:
- Deflections under service loads
- Steel weight for each option
- Floor-to-floor height implications

Example: Lateral system comparison

Model the same building with three lateral systems:
1. Perimeter moment frames
2. Interior braced frames
3. Concrete shear walls at core

Compare drift, period, steel tonnage, and foundation demands.

The agent handles the repetitive modeling work, letting you focus on engineering decisions.

Best Practices

Starting New Model
Modifying Models
Load Application

Always specify units firstInclude units in your opening prompt: “Create a model using kip-ft units…”Build geometry before loadsCreate structure first → Review screenshot → Apply loads → Verify patterns → Run analysisSave incrementallySave at major milestones: “Save as ‘Building_BaseFrame_v1.sdb’ before we modify the lateral system”

Troubleshooting

Model Doesn’t Look Right

Request Multiple Views

Show me:
- Isometric view
- Plan view at level 2
- Elevation along gridline A

Check Geometry Details

List all frame members with their coordinates and sections.

Start Fresh if Needed

This isn't quite right. Let's create a new model.
This time, use 4 bays @ 25ft instead of 5 bays @ 20ft.

Agent Seems Stuck

Ask for Status

What's the current status? Are you stuck on something?

Simplify the Request

Let's pause. Just create the basic frame geometry
without loads for now.

Break It Down

Instead of one complex prompt, use a sequence:

Create geometry
Add lateral system
Apply loads
Run analysis

Loads Not Applied Correctly

Verify Load Patterns

List all load patterns and show which members have
loads in the DEAD case.

Check Direction

Verify the loads are applied downward (gravity).
Reapply if the direction is wrong.

Visualize

Screenshot with load arrows visible.

Real-World Workflow

A complete design session showing iteration and refinement:

Initial Model

Create a 4-story office building:
- 150ft x 100ft plan
- 5 bays @ 30ft in long direction
- 4 bays @ 25ft in short direction
- Story heights: 15ft ground, 13ft typical
- Use engineering judgment for member sizes
- Units: kip-ft

Agent creates model with W14x176 columns, W24x62 beams

Optimize

Beams seem heavy. Try W21x50 for levels 2-4,
keep W24x62 at ground only.

Agent updates sections

Add Lateral System

Make perimeter frames on gridlines A and E moment-connected
for lateral resistance.

Agent modifies connections

Apply Loads

Floor loads:
- Dead: 100psf (slab + MEP + ceiling)
- Live: 50psf (office)
- Roof: Dead 80psf, Live 20psf

Create ASCE 7 gravity combinations.

Agent applies loads and combinations

Verify

Before analysis, show:
Isometric with loads visible
Total applied loads by level
List of load combinations

Agent provides verification package

Save

Save as 'Office_Gravity_Rev1.sdb'

Agent saves and provides download link

Tips for Success

Iterate freely - Don’t expect perfection first try. Refine with follow-ups: “Can you adjust the bay spacing to be more uniform?”
Interactive selection - Click elements in the 3D viewer to select them, then ask the agent to modify your selection
Request screenshots - Ask for visual verification at key stages: “Show isometric view to confirm bracing layout”
Upload references - Attach floor plans, sketches, or existing models to guide the agent and convey complex information visually
Compare options - Generate multiple design variations quickly for value engineering and optimization studies

Next Steps

Try It Now

Build a simple 2-story frame to get comfortable with the workflowGo to app.stru.ai

Upload a Sketch

Try creating a model from a floor plan or structural drawing

Run a Parametric Study

Generate 3-5 design variations and compare them

Study Existing Model

Have the agent analyze and explain one of your existing models

Get Help

Questions? Email bhosh@stru.ai or book a callcal.com/bhosh

Reference Codes

Use @ in prompts to search ASCE 7, ACI 318, AISC 360, IBC

Getting Started

Using Stru AI

Advanced

​Getting Started

​What You’ll See

​ETABS vs SAP2000: Which Agent?

ETABS Agent

SAP2000 Agent

​Writing Effective Prompts

​The Golden Rule

​Key Prompt Elements

​Common Use Cases

​1. Regular Building Frame

​2. Steel Truss Bridge

​3. Adding Lateral System

​4. Modifying Existing Model

​5. Load Combinations

​Advanced Usage

​Study and Recreate Existing Models

​Compare Two Models

​Use Sketches and Floor Plans

​Parametric Design and Iterations

​Best Practices

​Troubleshooting

​Model Doesn’t Look Right

​Agent Seems Stuck

​Loads Not Applied Correctly

​Real-World Workflow

​Tips for Success

​Next Steps

Try It Now

Upload a Sketch

Run a Parametric Study

Study Existing Model

Get Help

Reference Codes

Getting Started

What You’ll See

ETABS vs SAP2000: Which Agent?

Writing Effective Prompts

The Golden Rule

Key Prompt Elements

Common Use Cases

1. Regular Building Frame

2. Steel Truss Bridge

3. Adding Lateral System

4. Modifying Existing Model

5. Load Combinations

Advanced Usage

Study and Recreate Existing Models

Compare Two Models

Use Sketches and Floor Plans

Parametric Design and Iterations

Best Practices

Troubleshooting

Model Doesn’t Look Right

Agent Seems Stuck

Loads Not Applied Correctly

Real-World Workflow

Tips for Success

Next Steps