King-Post Roof Truss
King-post roof truss with a 120 N symmetric central apex load; the king post is a zero-force member by the collinear-joint rule, rafters carry compression (−100 N), and the horizontal tie-beam carries tension (+80 N per half).
Category: truss · Difficulty: Basic
Solution
| Support | Rx (N) | Ry (N) | Mz (N·m) |
|---|---|---|---|
| A | 0 | 60 | 0 |
| C | 0 | 60 | 0 |
| Member | Axial force (N) | Sense |
|---|---|---|
| Member A–B | 80 | Tension |
| Member B–C | 80 | Tension |
| Member A–D | -100 | Compression |
| Member D–C | -100 | Compression |
| Member B–D | 0 | — |
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.