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Comment by ars | Hacker News Reader

I'm actually surprised at how many buildings seem structurally basically still standing.

Especially the granaries right next to the epicenter.

Is it really that easy to build a building that can handle explosions like this?

Grain elevators (which that building is) can undergo fairly extreme loading so they are constructed from thick, steel-reinforced concrete. Depending on the details, the walls can be a substantial fraction of a meter in thickness. Additionally, there was tens of meters of standoff distance between the explosive and the grain elevators, which significantly reduces the peak stress it needs to endure.

Due to the height of the grain column, they are designed to withstand enormous pressures induced by having extremely tall columns of grain concurrent with undergoing lateral stresses from typhoon/tornado velocity winds. While they are not designed to be resistant to the shock wave characteristic of large detonations per se, being built with so much reinforced concrete lends some of that property naturally.

The warehouses that were obliterated entirely, if I had to guess they were steel truss with corrugated steel skins. One of the lowest cost ways to cover the largest area in square meters possible. Basically large versions of these steel truss horse barns, see interior photo:

https://www.worldwidesteelbuildings.com/steel-buildings/hors...

https://www.metalbuildingoutlet.com/images/steelequestrianbu...

> Is it really that easy to build a building that can handle explosions like this?

It's probably not that hard to have some sort of structural parts still standing but these things are as good as destroyed (even worse because now they'll have to setup a controlled demolition on a potentially unstable structure). A good 50% of the silos aren't there anymore, I guess the enormous amount of grain inside absorbed and dissipated a lot of the blast. They're basically the building equivalent of sandbags.

Even the famous building in Hiroshima survived being relatively close to the epicenter due to its construction.

I read somewhere that the way the harbour and the storage buildings where structured(probably not intentionally) directed a big part oft the blast downwards, hence the crater. Matches the Videos i've seen were the explosion was sharply going into the sky. Only the shockwave was horizontal.

Purely from a physics/explosives effectiveness standpoint, the destruction would have been much greater if it had occurred at 200-300m above ground level. This is one of the reasons why air drop freefall nuclear bombs (10-20 kiloton class) were designed with radar fuses to explode at a certain height above the target, and not at ground level. Except when intended to destroy a bunker.

Because the explosion occurred at ground level at least some of its energy was directed into excavating a crater and not destructive shockwave traveling outwards.

Also, IIRC air burst nuclear weapons produce less fallout.

For nuclear war planners, fallout is probably a feature.

Not for theoretical defensive tactical use in Korea / Germany / Israel / similar

Two kinds of nuke classes:

1. Strategic -- The world is going to die nukes. These are big nukes on ICBMs. If the opponent launches a strategic nuke, you launch all of yours and kill them too.

2. Tactical -- Small nukes that you shoot at the opponent's army before sending in your troops.

You're thinking of strategic nukes. But strategic nukes are far weaker if you have a dirty explosion: its probably better to have a more complete bomb. Tactical nukes absolutely must be clean, because your own troops are in the area.

Strategic nukes are typically fission-fusion-fission devices with both more yield and more fallout than a cleaner fission-fusion design of the same weight.

One can think of an explosion causing a roughly spherical shockwave. For a ground level explosion there's a relatively narrow "band" of that shockwave that travels along the surface of the earth damaging buildings and other stuff, the rest is either directed upwards, or as you say, to create a crater (and a lot of the "cratering energy" will be reflected upwards towards the sky as well).

A ground level explosion also means that nearby buildings and geography (hills etc.) shield things behind them, reducing the destructive effect.

With an airburst you have a more even distribution of destructive energy over a larger area.

One of the videos, when you step it frame by frame, manages to capture a nearly spherical fireball [1]. The next frame seems to suggest (to my amateur eyes) that the tall grain silos is causing a bit of a reflection of the fireball. Other than the grain silos, though, there doesn't seem to be any other factors shaping the blast.

[1] https://www.reddit.com/r/nextfuckinglevel/comments/i420ir/th...

Reinforced walls, no windows, angled inwards in a truncated pyramid to deflect energy up. Maybe covering it with material that's expected to be blown away by an explosion is a good idea as well. If it's grassy it may even help to keep the building cool.

I doubt that when someone is designing a storage warehouse on a shipping pier that "deflecting explosion energy" is very high on the list. "How cheap can we cover the most square footage" (is square meterage a word) would be the #1 question.

Also in an area where you don't have to design for roof snow loading, risk of tornadoes or hurricanes, warehouse structures on a concrete slab can be built at lower cost, with lighter gauge material and less structural reinforcement.

> is square meterage a word

Square meters or (in cases like this where the unit is irrelevant) just "area".

Grain silos may also be built to withstand internal dust explosions.

Yeah, I'm surprised all the office or apartment buildings across the street seem to all be intact. Hope the people that were in those buildings are all right.

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