Lesson 2: Structures Under Stress
Every structure faces forces every day — the weight it carries, wind, earthquakes, and its own weight. Understanding how materials handle stress helps engineers build things that last.
Key Concepts
Compression and Tension
Compression squeezes — columns and arches are in compression. Tension stretches — cables and ropes are in tension. Most structures have both happening at once.
Bending and Shear
A horizontal beam bends under a load: the top is compressed, the bottom is stretched. Shear forces try to slide layers of material past each other, like scissors cutting.
Material Choice
Steel handles tension well. Concrete handles compression well. That is why reinforced concrete uses steel rods inside concrete — the concrete handles compression and the steel handles tension. Together they are much stronger than either alone.
🆕 Stress Visualizer
See how a beam responds to load. Red = compression, blue = tension.
✅ Check Your Understanding
1. What is compression?
2. Why does reinforced concrete use steel rods?
3. What happens to the top of a beam under a load?