Structures

Galileo’s prestige brought greater academic attention to the subject. In the mid-1650s, scholars began researching the ways in which different materials and structures behave under heavy loads. That same century, Robert Hooke also discovered how matter behaves at an atomic level.

Stress isn’t just a psychological problem affecting humans – structures can suffer from stress as well.

Stress tells us the degree to which atoms are being pushed apart. Strain, on the other hand, measures how far they’re being pushed apart

Some structures, like ancient churches, castles or monuments, have managed to stay intact for centuries or even millennia. What makes it possible for them to stay standing for so long?

Structures stay in place largely thanks to the compressive forces acting upon them. Unlike tensile forces, compressive forces push on a structure rather than pulling it.

Ancient people implicitly understood the principles of structures and their forces well before they could perform calculations about them.

Structures can fall apart when they develop cracks or when new material is added onto them. C. E. Inglis wrote about this in 1913.

Holes and cracks aren't the only agents of local stress, either. The addition of new material can also cause stress by increasing the structure's stiffness. So, if you put a patch on a torn piece of clothing, for example, it might just cause it to tear even more.

When a person gets frustrated or stressed out, they will often dwell on their problems, which only serves to increase their stress levels. A similar phenomenon occurs in metal – and, appropriately enough, it's called fatigue.

Fatigue occurs when the heavy load on a metal fluctuates and causes it to lose strength. People first noticed this phenomenon during the industrial revolution, when machinery would sometimes break when it was moved.

Structures are a fundamental part of both the man-made and natural worlds. And while a rooftop and a horse would seem to have little in common, they're affected by the same scientific concepts that keep structures intact.

Stress, strain, force and strength are the keys to designing and maintaining the structures so important to our everyday lives, and researchers play a critical role in keeping us safe from their collapse.