Statically Determinate Check
Enter member, reaction, joint, and release counts to instantly check if a 2D structure is statically determinate, indeterminate, or a mechanism.
Structure Parameters
Total number of structural members
Pin = 2, Roller = 1, Fixed = 3
Total number of joints (nodes)
Result
Degree of Static Indeterminacy
Equation Breakdown
Enter structure parameters and click
Check Determinacy to see the result.
Support Reaction Reference
| Support Type | Reactions (r) | Constraints |
|---|---|---|
| Pin / Hinge | 2 | Horizontal + Vertical force |
| Roller | 1 | Normal force only |
| Fixed (Cantilever) | 3 | 2 forces + 1 moment |
| Link / Sliding | 1 | One direction only |
Summary
Enter member, reaction, joint, and release counts to instantly check if a 2D structure is statically determinate, indeterminate, or a mechanism.
How it works
- Select the structure type: Truss or Frame.
- Enter the number of members (m), reactions (r), and joints (j).
- For frames, also enter the number of internal hinges/releases (c).
- The tool calculates the Degree of Static Indeterminacy (DSI).
- A DSI of 0 means determinate; positive means indeterminate; negative means a mechanism.
Use cases
- Quickly verify hand calculations in structural engineering coursework.
- Check trusses and portal frames before full analysis.
- Teach students the concept of static determinacy interactively.
- Pre-screen structures for suitability of the force method or stiffness method.
- Confirm that internal hinges are correctly counted in frames.
- Validate simple beam, cantilever, or propped-cantilever configurations.
Frequently Asked Questions
Last updated: 2026-06-10 ·
Reviewed by Nham Vu