Pratt Bridge Truss — Method of Sections
Multi-panel Pratt bridge truss solved by method of sections; a single diagonal cut through three members isolates the required forces without solving every joint — the canonical demonstration of sections efficiency over joints.
Category: truss · Difficulty: Advanced
Solution
| Support | Rx (N) | Ry (N) | Mz (N·m) |
|---|---|---|---|
| A | 0 | 30 | 0 |
| G | 0 | 30 | 0 |
| Member | Axial force (N) | Sense |
|---|---|---|
| Member 13 | 30 | Tension |
| Member 14 | 30 | Tension |
| Member 15 | 60 | Tension |
| Member 16 | 60 | Tension |
| Member 17 | 30 | Tension |
| Member 18 | 30 | Tension |
| Member 19 | -60 | Compression |
| Member 20 | -90 | Compression |
| Member 21 | -90 | Compression |
| Member 22 | -60 | Compression |
| Member 23 | -42.426 | Compression |
| Member 24 | -42.426 | Compression |
| Member 25 | 0 | — |
| Member 26 | -30 | Compression |
| Member 27 | 0 | — |
| Member 28 | -30 | Compression |
| Member 29 | 0 | — |
| Member 30 | 42.426 | Tension |
| Member 31 | 42.426 | Tension |
| Member 32 | 42.426 | Tension |
| Member 33 | 42.426 | Tension |
All reaction values are computed by the StatIQ structural engine, not generated text. Signs follow the solver's convention: a positive Ry acts upward, a negative Ry downward; a positive M is counter-clockwise.