Why Triangles Are Strong

Design a bridge, drive a truck across it, and see the real forces in every beam. Which design carries the most for the least material?

Tension, Compression & Bending

Every beam is being stretched (tension), squeezed (compression) or bent. The thicker and brighter it glows, the closer it is to its limit.

A beam fails when the stress gets too big for the material (it yields), but a long, thin beam that is squeezed fails much earlier: it buckles sideways. Triangles turn bending into pure stretching and squeezing, which beams handle far better.

How to Experiment

  1. Pick a design and a material. Every design has the same road deck and the same truss members; only the arrangement differs.
  2. Set the truck's mass and position, or press Drive across.
  3. Read "Can carry about…" and compare designs.
  4. Tap a beam to see its force, tap it again to remove it (and again to put it back). Which beams really matter?

What's happening?

Controls

1. Bridge design

Bridge Status

SAFE

Can carry about: –

Most loaded beam: –

Maximum sag: 0.0 mm

Material used: –

Strength ÷ weight: –

Tap a beam to see its force.