How do skyscrapers manage to not topple?

Question

They are built on earth, earth crumbles, sinks, even moves right? I see the apartments they build here in China and its all concrete and rebar. How do the builders stabilize the ground enough to allow all that weight and stress? Serious answers please.

Answer 1

They use the highest quality duct tape and self tapping screws.

Answer 2

they have many curved plates with a ball on it. where ground move the skyscraper just rolls allow and gravity bring in back to its original position

Answer 3

On soft ground, we drive or bore piles in until they reach hard stratum way down, perhaps some 20-30m or more depending on the soil conditions. On fairly hard ground the columns are supported by individual pads or a huge concrete base called a raft foundation covering the entire building footprint. These are perhaps some 1m below the ground floor or basement level. There is even a thing called a piled raft foundation combining the ideas of both piles and raft foundations. Individual pads usually employed for smaller buildings like say a house, the raft for much bigger structure like skyscrapers or condominium blocks etc.

I never studied abt seismic effects, but there are methods employed to cater for ground movements like shock absorbers and movement joints added at the interface betn the concrete column and the foundation. Structural frame is also designed for oscillations - usually a 2nd or 3rd order differential eqn kinda thing. All these are input and simulated on a 2d or 3d computer model to find the additional stresses in the structural frame of the building & designed accordingly.