How is it that concrete floors in stadiums move/wiggle when jumped on without collapsing?

Question

Basically, I went to a concert, thought we were all going to die, then we did not die.

In: Engineering

Answer 1

These structures aren’t solid concrete – for all its strength, concrete is also brittle and inflexible and makes a poor structural material when used alone. Imagine a very thin sheet of concrete – the stuff is basically crumbly glass.

Instead, the concrete walls and floors are reinforced with steel rods and much of the structural strength for the building comes from steel beams and pillars inside or behind the concrete.

The steel is more flexible than the concrete, and can absorb all that energy and vibration without shattering.