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 | 30000 | 0 |
| G | 0 | 30000 | 0 |
| Member | Axial force (N) | Sense |
|---|---|---|
| Member A–B | 30000 | Tension |
| Member B–C | 30000 | Tension |
| Member C–D | 60000 | Tension |
| Member D–E | 60000 | Tension |
| Member E–F | 30000 | Tension |
| Member F–G | 30000 | Tension |
| Member H–I | -60000 | Compression |
| Member I–J | -90000 | Compression |
| Member J–K | -90000 | Compression |
| Member K–L | -60000 | Compression |
| Member A–H | -42426 | Compression |
| Member G–L | -42426 | Compression |
| Member B–H | 0 | — |
| Member C–I | -30000 | Compression |
| Member D–J | 0 | — |
| Member E–K | -30000 | Compression |
| Member F–L | 0 | — |
| Member H–C | 42426 | Tension |
| Member I–D | 42426 | Tension |
| Member K–D | 42426 | Tension |
| Member L–E | 42426 | 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.