How can an object pass through a building without taking significant damage?

Question

A kaiju swinging its arm through a building, a superhero that, locked in battle with a villain, flies through several buildings, a huge mecha that uses its ax on a skyscraper, like a lumberjack would on a tree. We have seen similar scenarios several times in fiction, and the constant is that the object, regardless of what it is, goes through the building without taking any apparent damage, and without losing functionality.

In real life, we don't have kaijus, superheroes or giant mecha, but we do have some unfortunate examples of large objects hitting buildings (for example, the 9/11 attacks), and in these, we don't see that the object hitting the building was able to pass through it, let alone without taking damage. So, in a fictional context, that tries not to get detached from the physics of the real world, what characteristics would an object need to be able to pass through a building without suffering damage?

I'm not referring to it being invulnerable. It can still scratch and wear away, but it doesn't have to take destructive or disabling damage.

Answer 1

All you need is to be stronger than Glass.

Most buildings have as minimal 'structure' as possible - not only to save money and to reduce resources used, but increase natural light penetration and insulation.

For instance, here is a plan of a typical 'skyscraper' commercial building: As you can see, the main support structure is normally located at the centre of the building by a concrete lift core. The light coloured walls are lightweight partitions - usually of felt or plasterboard. A sparsely spaced external perimeter of columns is sometimes used to grow the size of each floor.

As you can see then, the external envelope of the building (ie. what you 'see' when you look at it) is simply light cladding, or glass.

It is actually easily conceivable for an object to go through the glass without any damage, and also punch through lightweight partitions also, with little or no damage to itself.

If, however the external columns or the internal concrete core structure were damaged, the building will likely collapse. In your case, to go through a pretensioned steel reinforced concrete column without any damage you would require something with a lot more mass and structural integrity than even a high-speed aircraft, possibly a very dense, reinforced material with a cutting edge geometry at extreme speeds. It is not necessarily the concrete, but the pre-tensioned steel within that would need to be cut, something that many depictions (like in Spiderman with the Crane Arm) would simply not achieve.

However, it may be simpler to simply penetrate the glass, for which almost any metal material would be sufficient.

Note: It is worth noting that in your World Trade Centre reference, it was not the aircraft that caused the towers to collapse, but the burning fuel on-board, which heated the concrete structure constantly over a period of time hotter and hotter until the tensioned steel reinforcement within was weakened enough to cause structural failure. This was why after the impacts the WTC towers took a long time until they collapsed.

Answer 2

Hardness, Sharpness and Weight

Hardness is basically a materials resistance to being scratched and being dented. Diamonds are the worlds hardest material, and can scratch any other material without damaging themselves*. Technically, you would need another Diamond to scratch a diamond.

Now using Diamond edges for most weapons isn't great. Diamond's hardness causes it to be brittle and under certain pressures, the diamond is going to shatter.

The second part is Sharpness. The Sharper an object, the better its ability to split through the atoms of another object. A pointy diamond is going to pierce through a nice and flat diamond surface, and that allows us to slowly cut a diamond into shape.

Now all high-rise buildings are made up of a mixture of Concrete and Steel, so to have a weapon capable of going through these buildings, you would need something with a higher hardness than steel, and be sharp enough to initiate a cut into the steel (Like Diamond Bat isn't going through a steel pole, unless you exert so much force that you essentially stretch and snap the steel pole by materially deforming it).

I would imagine a weapon of such capabilities would need to be made from a mixture of Ceramics on the outside to provide a hard and sharp cutting edge, and a core of a software material (e.g. Steel/Iron) which would be able to absorb the shock of the impact and prevent the Ceramic edge from just shattering on impact.

The final aspect would be Weight. Because you need momentum to push through objects. At that scale, if you chop a skyscraper apart, not only are you cutting through the building, your going to push the top half of the building up a bit as your weapon cuts through it. So you need that raw power and momentum behind it to make sure you get all the way through and your blade doesn't get stuck halfway through because the skyscraper is just too heavy and pinning your blade.

Answer 3

A weapon (or kaiju body part) must simply be more structurally sound than the building.

Most things we humans make today are thin shelled bits of materials that wrap around something more complicated. Most vehicles' shells are simply too thin to withstand big, thick, heavy walls of cement or mortar. (Similar argument for applies to vehicles and trees and steel girders.)

Structural integrity can be achieved through several means, usually by...

• being of a more tough material (the area under a stress-strain curve, particularly the elastic region for no visible damage)
• distributing forces more acutely in the target than the weapon, meaning lower stresses and therefore less damage to the weapon

A wrecking ball and chisels do both of these things. The sphere of a ball and sharp points focus force down to a small area, and the tough steel (or other material) can simply withstand more damage before deformation.

It should be noted that toughness, damage, and deformation here are used in a material science sense. That's a little different than normal usage. This field gets people degrees, so consult your nearest mechanical, materials, or structural engineer for more details.

Answer 4

flox mentions being "stronger than glass". There's a major caveat there: these are not normal house windows. Normal double-pane residential windows are about 2-3mm thick (3/32"). Skyscraper windows are thicker (6mm or more).

Then there's the movies, which make breaking glass seem trivial (either by using untempered glass or by using hidden explosive charges to ensure the glass shatters on queue). Not only is this glass thicker, it's also tempered. Tempering means there's a thin plastic film that keeps the glass from completely shattering and making all sorts of dangerous shards. If you have a smart phone, it uses highly tempered glass over the screen, which can spider easily, but not break. It also keeps the glass from letting anything through easily.

The key on going through tempered glass (without something with a lot of force, like a wrecking ball) is to focus the energy onto a single point with something like a pyramid or conical shape. The glass will shatter and the top of this object will force the hole open until the whole object is in. This shouldn't damage the object much, if at all.

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The second key is your object should not be larger than around 10ft(3m). Each floor will be an impediment to your object, and hitting one along the side will almost certainly stop it. Skyscraper floors are typically in the 10-14ft(3-4m) range. You want to give your object a chance to pass through two windows cleanly. An airplane of any size is unlikely to be able to survive this, since a smaller aircraft will likely not have wings that can survive the trip (flying through a building in an airplane, period, is quite the stunt by itself).

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Now you need to contend with what's inside. The elevator and stairs are almost always reinforced to help ensure people can escape. Hitting closer to the edge should fare better. If this is an office building, it's unlikely there's interior walls everywhere. An apartment building... not so much. The fewer objects in your path here, the better. There's still likely to be cubicle walls (they're not attached to the floor or ceiling so they can give some), but some offices have no walls at all (called open offices). As such, if you're not going through a lot of material in between, your object need not be metal.

In theory, you could do this with a simple metal cap (say a post cap) to shatter the glass, and then a wooden structure behind to get inside (I am assuming an all-glass exterior with no exterior wires). It could strike minimal objects inside and exit the other side. Would still need a decent amount of force for penetration, but nothing a well-built box of 2x4's couldn't handle.

Answer 5

The problem here is energy.

So, the things we build stuff out of are all solid right? Solid as in the material state. Being solid is a relatively low energy state. This is usually great, because being in a high energy stake makes things move around, and we usually want them to stay still.

But, when we start dealing with things on a massive scale, like giant monsters or huge robots, or the raw power super heroes throw around, this requires massive amounts of energy.

we also make sky scrapers out of types of matter that require huge amounts of energy to deform, and because of how mater and energy interact, any energy that king Kong puts on the empire state building, the building will reflect back onto king Kong. You see this exact effect in a plane hitting a tower. The tower stays up longer than the plane, because the tower reflects the same stress the plane put on the tower, and towers are built to take more stress than planes. And for the effect you want,we need subjects that can take much more stress than towers can.

So the question becomes, how do we build a man who can take the stress of hitting multiple buildings, that is, the stress he himself inflicted on those buildings by smashing into them, plus whatever sent him flying in the first place, while not turning into a pulp?

It depends on how crazy you want to get with it. There are materials out there that can handle more energy being put into them than glass and steel, but you might want make something a bit more fantastic. Personal energy shields are not super realistic, but they do technically exist, and the magnetic field around our planet mitigates insane amounts of energy. If you hand an energy field around the subject, it might give you the effect you want, without making the subject itself completely indestructible.

Answer 6

There were examples of rockets penetrating deep into the soil and bunkers just by kinetic energy, before exploding. Example here.

Recently I watched a video showing a rocket going into through at least 4 floors of a building into a basement and then not exploding for whatever reason. So video could show how basically a hole through each floor concrete structure was made.

Unfortunately that was on telegram so I can't link.