No. There is no force in the universe that could ever cause a skyscraper to ‘topple over’ sideways. Regardless of how it looks tall buildings are not solid objects, they are a pile of framework steel constantly in balance against the force of gravity pulling down trying to collapse it under its own weight. Even if you could somehow magically ‘push’ against an entire side of one the instant its center of gravity moved slightly off-center it will collapse straight down. Every time. No exceptions.
In fact, if you watch the video of the second WTC tower collapsing, because it was struck much lower the upper half actually did start to tip a little when the middle gave way. But, as stated above, it immediately collapsed straight down.
If you take the supports out of one side of a high rise it will begin to lean a little and then collapse. That is when gravity begins to take over Most of the parts will fall straight down but the pile will be higher on the side where the supports were removed. But the building is not going to arc down.
Why would it lean at all if all support below is removed simultaneously? It’s only when support is removed unequally that it will tilt. There is no inherent tendency to tilt over in all structures.
Most buildings are tall and thick. Most trees are tall and thin. Think there might be an important difference here with respect to gravity and the center of it?
The World Trade Center was a new design where the supporting walls were on the outside. Usually, there’s a central core that holds up the building, but that takes up space, so the architect did it so the outside wall supported everything. Once the wall was breached, the floor above the breach would fall down, creating the chain reaction we saw.
Older building would stand up better, but would be more likely to topple sideways, since the central core would prevent the floors from falling straight down.
Before buildings were made with structural steel frameworks they relied on masonry walls for support. Consequently buildings couldn’t be much taller than ten stories. As such, no skeletal steel supported building much taller than ten stories could ever topple over like a tree. They always collapse straight down under their own weight.
Because a tall building is subject to a strong wind load and experiences a fair amount of tension on the side facing the direction where the wind is coming from. And tall buildings do “bend” because of this.
It’s also the reason that concrete columns contain steel reinforcing bars. It’s not for compression (the concrete is more than adequate for that). Also, a tall building can, in fact, topple over like a domino. Particularly if they are made from steel frames (which are strong in tension).
The reason the World Trade Center towers came crashing straight down is because they were designed as a bunch of concrete slabs suspended by pins within a tall metal tube. The collapse started towards the top where the planes hit and each slab pancaked straight down on the floor below it.
It’s just physics. Look at that video above. Again, its barely more than ten stories high (and very narrow). The simple fact is there is no building material that can maintain rigidity beyond its designed size & shape without collapsing under its own weight. Tall buildings may look like static ‘blocks’ but they’re not. They are in constant compression, tension etc. against gravity. If you upset that fairly delicate balance beyond a certain point the whole structure just gives way like a house of cards. There was nothing particularly special about the Twin Towers (excluding the girders losing their fireproofing and then bending) that made it collapse straight down. If the Empire State or Chrysler Buildings were subjected to say a large enough earthquake they too would collapse in essentially the same way.
You’re missing the point.
Nobody here has said that a skyscraper will remain completely intact and fall over so that the top will land exactly it’s height away from the base.
But, buildings are still structures, and the steel framework is welded or riveted together, to give them some amount of rigidity. If the base of a tall building was blown out on one side, the building would not fall straight down - it would lean over, and collapse at some point, but the rubble pile would extend for a significant percentage of the height of the building.
That is one reason that skyscrapers are disassembled and not imploded.
We probably need to define “skyscraper” and then for individual examples look carefully at the manner in which they are constructed.
The Empire State building, like all those built at that time is a steel girder structure. It is steel riveted together. These buildings defined the idea of a skyscraper. They are different to a simply tall building. Such a building will have a significant tensile strength, and if toppled would be expected to hold together much better than a building built out of ordinary reinforced concrete. It will still buckle and fracture, but it won’t crumble into a shower of rubble falling straight down. A building built out of prestressed reinforced concrete is another matter. It has a greater tensile strength, but as soon as the concrete starts to fracture the internal tension will probably result in a catastrophic collapse of the structure.
The various videos of chimneys being felled demonstrates the question. Brick chimneys fall a little and then dissolve into a rain of bricks, whilst the various concrete ones have varying amounts of topple before they fracture.
But in order to topple a building, you need to give it some impetus to fall, like removing a section on one side. Dropping chimneys will involve charges placed at one side of the base, and even some preparatory removal of structure (rather like felling a tree.) Symmetric destruction of the base of a building will get movement straight down, and a nice downward collapse. You see some such demolitions go wrong and the building partially topple if there isn’t symmetric destruction.
Here is a pretty good vid of demolitions gone wrong. - YouTube WARNNG: loud music.
Anyhow, in there you’ll see several examples of structures that fall straight down but don’t self-disassemble as expected. And several of structures that tip over and don’t self-disassemble as expected.
Bottom line: a tall structure is neither a simple stack of loose blocks, nor is it a perfectly rigid object with infinite strength and a firm anchor point about which to pivot. As **Francis Vaughn **said so eloquently, a masonry chimney is close to the former and produces a “rain of bricks”. Whereas Alex Roger’s tall steel pipe is close to the other extreme, something very strong in tension and torsion with a solidly anchored pivot.
So any intact structure falling down is a mix of gravity pulling each small chunk straight down with one amount of force, and each chunk being pulled in whatever direction(s) with whatever strength(es) by all the chunks it’s connected to. While the connections are stronger than the forces it remains a single unitary object. As the forces grow to exceed the connections’ strengths, those connections fail and the structure fragments. The more it breaks up, the more each ever-smaller chunk’s behavior becomes dominated by gravity alone.
I’m disappointed! Can’t we all endeavor just a little more to trainwreck this thread into yet another WTC conspiracy screed? We’ve got most of the ingredients… we just need the critical mass of a nut or two to really get us going.
I have my BS & MS in structural engineering. “How buildings fall” was never a criteria in design work and I don’t even recall seeing it mentioned in any of the various codes.
We did spend a considerable amount of time designing buildings to NOT fall down and by necessity this included studying collapse mechanisms but that’s not the same.
I’m sure that the companies which do controlled demolitions study this intensely but AFAIK it’s not part of normal structural design.
To the OP, people have pretty much covered the basics but tall buildings don’t generally topple like trees because they are not trees. They’re both tall but that’s about it. A tree is far stronger for it’s size in certain ways compared to a building; tilt a tree 45 degrees and it’ll probably be fine. Tilt a skyscraper at 45 degrees and it’ll likely fall apart because it’s not designed to withstand that type of loading.
If you want an example of something that can withstand a huge compressive load collapsing “straight down”, stand on an empty soda can. Do it carefully and it’ll hold your weight just fine, despite the supporting structure consisting of nothing more than an extremely thin sheet of aluminum. Then have someone tap the side of a can with a yardstick - a tiny bit of local buckling in the wall of the can and crunch, your weight smashes straight down and the can becomes a circle.
ETA - and then the CIA operatives will change the live video feed of the event and freefall plus explosive thermite.