Nib asked, and Nib — askNib's tutor — drew the answer live at a whiteboard. This is the spoken transcript; enable JavaScript to watch it drawn.
how do skyscrapers not fall over
A tower is not a stack of blocks that could tip. It is pinned deep: the Burj Khalifa rests on close to two hundred concrete piles.
It has two jobs: carry its weight down, and survive wind pushing sideways. Wind grows stronger with height, and often decides the design of the tallest towers.
So picture the tower as a huge stiff beam pinned at the bottom. Wind is strongest at the top and tries to bend it over, like a ruler.
A stiff core does the heavy work. Outriggers, stiff arms, tie the core to the outer columns, so the whole width of the building joins the fight.
Shape helps too. The Burj Khalifa's stepped Y shape was tuned in wind tunnels, so the wind's swirls break up instead of rocking it.
A few towers add a giant pendulum. Taipei 101 hangs a steel ball of about six hundred sixty tonnes near the top, swinging against the sway.
So the whole idea: deep piles carry the weight, a stiff core with outriggers resists the bend, the shape breaks up the swirls, and a pendulum calms the sway.
Next time you look up at a tower, remember: it is a tall beam pinned in the ground, and every part of it is helping hold it up.