Shared truss vocabulary
- Top chord — the horizontal member along the top. Usually in compression.
- Bottom chord — the horizontal member along the bottom. Usually in tension.
- Vertical — upright members connecting top to bottom chord.
- Diagonal — slanted members forming triangles with verticals and chords.
- Panel — one section between two verticals (one triangle or rectangle).
1. Pratt Truss
Members in tension (blue): bottom chord, diagonals
Members in compression (red): top chord, verticals
Typical use: short-to-medium span steel and timber bridges
Good for Y7 build: diagonals in tension = less buckling risk. Easiest truss to build cleanly.
2. Howe Truss
Members in tension (blue): bottom chord, verticals
Members in compression (red): top chord, diagonals
Typical use: timber bridges (timber is good at compression)
For Y7 build: watch out — diagonals in compression are prone to buckling with thin sticks.
3. Warren Truss
Members alternate compression and tension — each diagonal is one or the other
Typical use: medium-span steel bridges, many Australian rail bridges
For Y7 build: elegant and uses FEWER sticks than Pratt. But alignment is trickier because diagonals must meet at clean points.
4. K-Truss
Shorter diagonals = less buckling risk (critical for tall trusses)
Typical use: Eiffel Tower (vertical use), tall highway signs, very wide bridges
For Y7 build: complicated. Only attempt if you're confident with Pratt first. Uses the MOST sticks.
Which should I pick?
| Truss | Ease | Stick count | Load capacity | Recommended for |
|---|---|---|---|---|
| Pratt | ⭐⭐⭐⭐⭐ Easiest | Medium | High | Most Y7 pairs |
| Howe | ⭐⭐⭐ Medium | Medium | Medium (buckling risk) | Pairs confident in gluing |
| Warren | ⭐⭐ Trickier | Fewer | Medium-high | Pairs who want lowest mass |
| K-truss | ⭐ Hardest | Most | Very high | Extension students only |