🌉 Bridges & Structures

beam · arch · suspension · cable-stayed · compression · tension · engineering

Bridge Type	Max Span	Main Material	Best For	Famous Example

What forces act on bridges?

Every bridge must handle compression (squeezing forces) and tension (stretching forces) caused by the bridge's own weight and live loads (traffic, wind, earthquakes). The genius of bridge design is distributing these forces safely into the ground.

Why do different bridges suit different spans?

A simple beam bridge sags badly at long spans. An arch needs solid rock or ground to push against. Suspension bridges use enormous anchor blocks and tall towers — expensive but capable of kilometre-scale spans. The right choice depends on span, budget, ground conditions and aesthetics.

Key terms

Compression — force that squeezes and shortens material; stone and concrete resist this well Tension — force that stretches material; steel cables and rods excel under tension Deck — the roadway or railway surface that carries traffic Abutment — the solid support at each end of a bridge that transfers loads into the ground Load factor — multiplier applied to expected loads to ensure a safety margin (typically ×1.5)

🎯 Try this challenge

In the Forces Explorer, switch between all four bridge types with the same load (50 tons). Which one puts the most tension on the structure? Which one relies most on compression? Notice how the Arch almost entirely avoids tension — that's why Roman bridges built 2,000 years ago still stand today.

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