AE911 New Collapse Hypothesis

[Jeffrey Orling]

Just trying to understand this.

Are you saying you believe that ALL the columns (designated as 501, 502, 601, 602, etc.), from base to roof, self buckled due to their weight and being unbraced?

What about falling debris impacting a column and causing it to snap at a weld or causing it to buckle? Could some of those columns have been pulled horizontally due to falling debris impacting horizontal structural components connected to them causing them to snap ay a weld or buckle?

Clearly there were lateral loads from material falling on bracing beams. The outside rows of the core... 500, 600... 900 and 1000 framed shafts and very limited floor loads inside the core. The spire columns were more rigid the lower you go in their height and would take large lateral loads to topple them.
You can think of the core columns as a stack of columns one atop the other... all held in a 3D lattice by the bracing beams.
The outside the core floor areas were supported on the core side on a belt girder which was cantilevered from the core by 28 short beam stubs.

 

[Gamolon]

And we build to that height. We're certain. But we even build in a safety margin to be sure.

Can you please elaborate on what you believe a "safety margin" is when speaking of buildings?

 

[Gamolon]

Clearly there were lateral loads from material falling on bracing beams. The outside rows of the core... 500, 600... 900 and 1000 framed shafts and very limited floor loads inside the core. The spire columns were more rigid the lower you go in their height and would take large lateral loads to topple them.
You can think of the core columns as a stack of columns one atop the other... all held in a 3D lattice by the bracing beams.
The outside the core floor areas were supported on the core side on a belt girder which was cantilevered from the core by 28 short beam stubs.

That didn't really answer my question.

Are you saying you believe that ALL the columns (designated as 501, 502, 601, 602, etc.), from base to roof, self buckled due to their weight and being unbraced?

You believe that's the only way the columns came down? That's what it sounded like to me at least. I'm just trying to clarify in case I misunderstood.

 

[Thomas B]

Can you please elaborate on what you believe a "safety margin" is when speaking of buildings?

We know what will happen at a critical load. It will fail. We're pretty sure the building will never experience that load or will experience it only once in a hundred years. But, just to be sure, we make the building two or three (or whatever) times stronger than that.

 

[johnny plectrum]

Interesting. Thanks.

Do you know how the calculation would come out for the homogenous vs. welded versions? What would the maximum height of the unsupported column be in each case?

I think there are just too many unknowns to make speculative calculations of any value.

 

[Jeffrey Orling]

This is something I can't agree with. Expert opinion on this must have converged on the truth by now. Engineering students are being correctly taught why the towers collapsed. They are not being misled by experts who still don't get it.

The truth about the collapses is not known only to amateurs.

Bazant's math is correct.... but does not describe the WTC collapse.
He "missed" the runaway floor collapse as the cause.

That didn't really answer my question.

Are you saying you believe that ALL the columns (designated as 501, 502, 601, 602, etc.), from base to roof, self buckled due to their weight and being unbraced?

You believe that's the only way the columns came down? That's what it sounded like to me at least. I'm just trying to clarify in case I misunderstood.

yes...in addition to some jostling from debris

 

[Thomas B]

I think there are just too many unknowns to make speculative calculations of any value.

No, I mean just two "textbook" examples. Like in the MIT "tallest column" example. Just with different values for the thickness of the column wall and the radius that look more like the WTC columns.

 

[Gamolon]

We know what will happen at a critical load. It will fail. We're pretty sure the building will never experience that load or will experience it only once in a hundred years. But, just to be sure, we make the building two or three (or whatever) times stronger than that.

Critical load for every structural component or assembly?

Let's take the concrete floors for example. Are you saying the engineers calculated the dead/live loads for each floor and then made those floors two or three (or whatever) stronger than that?

What about the core columns at floor 74 for example. One engineer, Tony Szamboti, said the core had a safety factor of 5. And as you removed a percentage of the 47 core columns, the safety factor would decrease by the same percentage. And as long as you stayed above a safety factor of 1, you'd be okay.

Thoughts?

 

[Gamolon]

I reject the last part for sure.

Did you used to think it was controlled demolition that brought down the columns?

If so, what explanation/evidence changed your mind?

 

[Thomas B]

Thoughts?

Not really. I'm not sure what you're driving at. Buildings have a known critical load at which they are expected to fail. But it's usually well above (x 2, 3 ... 5 ... depending on the building) anything they're expected to actually have to face.

 

[Thomas B]

Did you used to think it was controlled demolition that brought down the columns?

If so, what explanation/evidence changed your mind?

I've said this before, but my view is that controlled demolition is easy to understand (from the point of view of physics) but impossible to believe. If it is true, the engineering profession is completely corrupt, and so is academia in general. A sociologically improbable conspiracy would be required to carry it out and cover it up. So, no, I have never thought that controlled demolition brought down the WTC.

That said, I don't understand how they actually collapsed. I wish there were a good popular book on the subject.

 

[econ41]

@Mendel your post explains in simple lay-person language the key aspects of the real collapse which I have explained in more "engineering" terms several times in THIS thread. And many occasions in other threads, Forums and Groups going back to Nov 2007.

But they're not homogenous, they're "lumpy", stronger at the edge and in the core, with mass density and resistance force also distributed unequally.

CORRECT. And the reality of "columns in core and at perimeter" with a large open office space - the "tube-in-tube" design is what makes "one-dimensional approximations" wrong. The presumption of homogeneity across the two horizontal dimensions of the plan. Which leads to columns not aligned, columns not taking the load.

The initial failure at the top was not symmetrical, either, we see the top block tipping to one side.

And "capacity increases" holds for the columns, but not for the floors!

Schneider's process halts because of this increase!

Yes. Yes. Yes.

And I explained this, with quotations, over a month ago, in post #8, so please stop flogging a dead horse.

You, me and at least one other (@Jeffrey Orling ) have presented explanations, coming from different approaches, using different terminology but saying essentially the same core of facts.

This is no longer up for discussion because your assertions have already been demonstrated to be false in this very thread, and you're just in denial about it. Unreasonably.

Sadly that is true.;

 

[Jeffrey Orling]

The loads on the columns hardly changed. There was some amount of load redistribution to carry the loads of the plane destroyed columns. When the floors collapsed the columns were "unloaded" from top to bottom as floors collapsed.

SOME COLUMNS IN THE CORE AT THE PLANE STRIKE ZONED FAILED
CORE COLUMNS DID NOT FAIL DURING THE COLLAPSE
PERIMETER COLUMN PANELS PEELED AWAY AS THE FLOORS COLLAPSED
THE COLLAPSE WAS

1. COLLAPSE / DESCENT OF THE UPPER BLOCK​

2. FLOOR COLLAPSE IN A RAPID RUNAWAY FASHION FROM TOP TO BOTTOM IN THE LOWER BLOCK​

3. COLUMNS TOPPLE OR BUCKLE AFTER FLOOR COLLAPSE (LOSS OF BRACING)​

 

[Gamolon]

Not really. I'm not sure what you're driving at. Buildings have a known critical load at which they are expected to fail. But it's usually well above (x 2, 3 ... 5 ... depending on the building) anything they're expected to actually have to face.

What do you mean when you say "known critical load at which they are expected to fail"? Fail as in complete collapse/destruction of the entire building?

 

[Jeffrey Orling]

What do you mean when you say "known critical load at which they are expected to fail"? Fail as in complete collapse/destruction of the entire building?

He's confusing the forest (the building) for the trees.... the building's elements... eg, columns, floors, beams... roof

A building does not have a factor or safety... the structural elements of the building each has a factor or safety. For a typical high rise the FOS of the structural elements is usually 2 or less.

https://theconstructor.org/structural-engg/safety-concept-in-structural-steel-design/4820/

 

[econ41]

I think there are just too many unknowns to make speculative calculations of any value.

That is not true. Especially framed as a global claim.

And the significance is much broader in impact than the specific "Euler Bucjkling" example you questioned.

For example, take the whole question of the Twin Tower's collapses. A much more complex issue than column Euler instability. There is more than sufficient evidence in the visual record and public domain to explain the collapse mechanisms, to explain how initial damage plus heat weakening from unfought fires caused the collapses, to explain why there was no need for "assistance" from so-called CD, and to know that no CT Truther has ever shown EITHER that CD was needed or that it was performed.

Yes much of the specific detail is not and never will be available. That is a big reason why many professional explanations fall short. But most of the "speculative calculations" don't need more than ballpark guesses PROVIDED we understand the mechanism of collapse. Most of the critical forces were simply "overwhelming"...

@Thomas B is recycling issues which are side tracks and derails which have already been explained multiple times. He keeps shifting his implied objective - looking for reasons to disagree rather than moving forward based on improving understanding.

 

[econ41]

For a typical high rise the FOS of the structural elements is usually 2 or less.

Which is reasonable at the level of individual elements. I would have expected 3 but I"m not familiar with the details of industry standard practice.

 

[econ41]

Not really. I'm not sure what you're driving at. Buildings have a known critical load at which they are expected to fail. But it's usually well above (x 2, 3 ... 5 ... depending on the building) anything they're expected to actually have to face.

Wrong. Fundamentally wrong. And the true situation has been explained to you on multiple previous occasions. "Factor of Safety" is NOT global. It does NOT apply to "Whole Buildings". And the concept of FoS is best avoided, not invoked, by persons who do not sufficiently understand it.

 

[econ41]

What about the core columns at floor 74 for example. One engineer, Tony Szamboti, said the core had a safety factor of 5. And as you removed a percentage of the 47 core columns, the safety factor would decrease by the same percentage. And as long as you stayed above a safety factor of 1, you'd be okay.

Thoughts?

I know it would be fun but do we really need to go there at this time?

The concept that removing a %age of columns results in uniform increasing loads on remaining columns has been one of the core errors of trutherdom from the earliest days of debate. And it is one issue that I have explained to Tony Szamboti several times. AND the only issue where I ever caught him out in deliberate lies. (On that very topic he hedged his bets on JREF - too many engineer debunkers who would know he was wrong. Whilst on Debate Politics - very few engineers - he blatantly repeated the untruth. Forgetting that I was a member of both Forums. )

BOTTOM LINE > IF you remove 25% of the columns from an array of columns it doesn't result in a uniform 33.3% increase in load on the other columns.

Here - an extreme case model to prove my point. A simplified "Twin Tower" with a "Top Block" supported on just three rows of columns. Original loads in GREEN. What happens to loads in the LEFT row and CENTRE row if the RIGHT row columns are cut? Assume the Top Block is rigid at this stage.

Spoiler: Answer

 

[econ41]

Bazant's math is correct....

Maybe. Are you aware @Jeffrey Orling of the paper "Some Misunderstandings Related to WTC Collapse Analysis" by Szuladzinski, Szamboti and Johns? One of their claims is that Bazant & Zhou over-estimated the energy and the B&Z conclusion was therefore wrong. Collapse should've been arrested for the abstract 1D approximation "Limit Case" proposed in the B&Z 2001/2 papers.
http://www.ae911truth.org/images/PDFs/Szuladzinski.Johns.Szamboti.pdf

The Szuladzinski, Szamboti and Johns claim has AFAIK never been falsified/disproven.. And Bazant has never responded to prove his original claim was correct (Or admit he was wrong!)

but does not describe the WTC collapse.

Correct. And that is the fact that @Thomas B is attempting to ignore or gloss over evade.

He "missed" the runaway floor collapse as the cause.

He set the real mechanisms to one side as "too hard at this early stage" with his B&Z papers 2001-2. And fell for his own trp in Bazant & Verdure 2007 which introduced the Crush Down/Crush Up hypothesis. Which is wrong - four fatal errors - if applied to the WTC Twin Towers. Most debunkers are not courageous enough to admit or even understand that Bazant was wrong. (Except one iconoclast who comments lèse-majesté by daring to disagree with the king.)

yes...in addition to some jostling from debris

Probably - jostling would be unavoidable.

 

[FatPhil]

The math is above my pay grade. However the real world example is a tell. Col 501 was about 75 stories tall and it toppled. Clearly its form, mass and height could not self support.

One thing to bear in mind is that the textbook examples are idealised cases where there's no significant externally-imposed perturbations on the column. Euler bucking is a positive-feedback effect, the corrective force available simply isn't enough to correct any perturbation. However, where there's detaching floors and beams tugging on or bashing into the uprights every which way, and with significant lateral loads like that you'd expect most columns to collapse well before reaching their theoretical slenderness limit.

An approximation to this should be modelable in a fairly simple balls-and-springs physics package, and I don't even see why you'd need a third dimension. Build a slender column at various ratios of its theoretical slenderness ratio, and see what kinds of magnitudes of perturbations (compared to the magnitudes of the compressive loads at play) applied at random points can bring upon buckling. (I see nothing in my distro that does the job, but apparently there was a package called xspringies way back that could have been up for the task, I'll see if I can build that on my system, but I'm not that hopeful, code/library-rot is a very real thing, and that package seems decades old.)

 

[Mendel]

An approximation to this should be modelable in a fairly simple balls-and-springs physics package,

Or play "World of Goo" (or its free game design lab predecessor "Tower of Goo").

Source: https://m.youtube.com/watch?v=w58z_u_QS7w


Source: https://m.youtube.com/watch?v=CXKBmuLrCco

The tower in the second video stays upright because the player manipulates it, and because there's a suction element above the top that keeps it upright.

It's a combination of the springiness and the perturbations that makes this game challenging and difficult to predict.

 

[Thomas B]

A building does not have a factor or safety... the structural elements of the building each has a factor or safety. For a typical high rise the FOS of the structural elements is usually 2 or less.

"Factor of Safety" is NOT global. It does NOT apply to "Whole Buildings". And the concept of FoS is best avoided, not invoked, by persons who do not sufficiently understand it.

I'm no expert (as you know). But this didn't seem right to me because it is my understanding that buildings (and especially the WTC towers) are designed to manage wind loads as whole structures. So I did a little googling, and I'd like to know how you square this with this "Whole Building Design Guide", published by the National Institute of Building Sciences:

After loads have been determined, it is necessary to determine a reasonable safety factor (when using allowable stress design) or reasonable load factor (when using strength design). For building envelope systems, a minimum safety factor of two is recommended.

https://www.wbdg.org/resources/wind-safety-building-envelope

Sometimes the two of you seem to know what you're talking about. And sometimes you say things that just make no sense and are wildly at odds with what a non-expert like me can easily find online.

In a related point, you constantly question my understanding and sincerity, and yet you claim to understand a structure and its collapse even though the basic math is "above your pay grade". (Until you actually do the math, Econ, I'll assume this goes for you as well.)

I fully admit that I don't understand the collapses. But I'm trying. It often seems like your main goal is to convince me (or the readers who follow along silently) that I never will, that I'm either too stupid or too stubborn to learn. But examples like this, where you say things about safety factors that can be easily falsified by the layman, lead me to question who is wasting whose time.

 

[Jeffrey Orling]

I'm no expert (as you know). But this didn't seem right to me because it is my understanding that buildings (and especially the WTC towers) are designed to manage wind loads as whole structures. So I did a little googling, and I'd like to know how you square this with this "Whole Building Design Guide", published by the National Institute of Building Sciences:

https://www.wbdg.org/resources/wind-safety-building-envelope

Sometimes the two of you seem to know what you're talking about. And sometimes you say things that just make no sense and are wildly at odds with what a non-expert like me can easily find online.

In a related point, you constantly question my understanding and sincerity, and yet you claim to understand a structure and its collapse even though the basic math is "above your pay grade". (Until you actually do the math, Econ, I'll assume this goes for you as well.)

I fully admit that I don't understand the collapses. But I'm trying. It often seems like your main goal is to convince me (or the readers who follow along silently) that I never will, that I'm either too stupid or too stubborn to learn. But examples like this, where you say things about safety factors that can be easily falsified by the layman, lead me to question who is wasting whose time.

Frankly my interest in the WTC was to satisfy my own curiosity, not teach others. So I may learn from others ... all online...but now as I think the collapses make sense to me my "goal" has been satisfied. I don't need to prove anything... do any math... or make any models.
One does need to understand basic structural principles. Educated as an architect I understand the principles of structure. As I stated many times understanding will come from accurate observations and adequate technical knowledge. The latter does not have to be advanced physics or engineering. ROOSD makes "sense"... is an observed phenomena and supported by basic structural principles.

You can lead a horse to water but you can make her think.

 

[Thomas B]

Frankly my interest in the WTC was to satisfy my own curiosity, not teach others. So I may learn from others ... all online...but now as I think the collapses make sense to me my "goal" has been satisfied. I don't need to prove anything... do any math... or make any models.
One does need to understand basic structural principles. As I stated many times the understanding will come from accurate observations and technical knowledge. The latter does not have to be advanced physics or engineering. ROOSD makes "sense"... is an observed phenomena and supported by basic structural principles.

You can lead a horse to water but you can make her think.

You're not even going to acknowledge your error?

You said that there is no safety factor for buildings and that the safety factor for elements is usually less than two. I found a credible source that says the safety factor for wind design of whole buildings is usually 2 or more.

You can show a horse your sources but you can't make him read them, I guess.

 

[Jeffrey Orling]

You're not even going to acknowledge your error?

You said that there is no safety factor for buildings and that the safety factor for elements is usually less than two. I found a credible source that says the safety factor for wind design of whole buildings is usually 2 or more.

You can show a horse your sources but you can't make him read them, I guess.

I stand by what I stated... and it's my understanding from reading. Elements, components have a safety factor... that is they can withstand more stress than they are expected to receive. All the elements should have a minimum safety factor which for high rise buildings is 2 or lower.
Buildings do not have safety factors. Every material has performance characteristics for tension, compression and so forth.

 

[Thomas B]

I stand by what I stated... and it's my understanding from reading.

I suppose it's possible that neither of us understands how those towers collapsed. I think that's going to be my assumption going forward. Thanks for your frankness, anyway.

 

[Jeffrey Orling]

I suppose it's possible that neither of us understands how those towers collapsed. I think that's going to be my assumption going forward. Thanks for your frankness, anyway.

Speak for yourself.
I am confident that I understand how the towers most likely collapsed.
You are willfully ignorant or simply not able to grasp basic engineering principles.
You are incapable of understanding the visual evidence (or denying what you see).

 

[Thomas B]

I am confident that I understand how the towers most likely collapsed.

Yes, I get that. It's just that I recently lost confidence in your grasp of engineering principles. That's fine. I don't understand them well enough either. Be well.

 

[Gamolon]

You're not even going to acknowledge your error?

You said that there is no safety factor for buildings and that the safety factor for elements is usually less than two. I found a credible source that says the safety factor for wind design of whole buildings is usually 2 or more.

You can show a horse your sources but you can't make him read them, I guess.

https://en.wikipedia.org/wiki/Factor_of_safety#:~:text=Buildings commonly use a factor,and most structures are redundant.

Buildings commonly use a factor of safety of 2.0 for each structural member. The value for buildings is relatively low because the loads are well understood and most structures are redundant.

https://www.onsitesafety.com/safety-articles/what-is-the-factor-of-safety/

Keep in mind:

Safety factors do not imply that a system is safe and free from accidents. Parts to a whole may all have the same factory of safety, but that does not give the system as a whole the same FoS. Likewise, stress to one part of whole can easily change the stress distribution to the whole itself. Remember, a factor of safety is a good tool to determine how to properly install and use equipment, but many other factors go into determining safety.

You didn't answer my question from before Thomas B. As far as your understanding, when a building surpasses it's factor of safety, does that mean complete collapse?

We know what will happen at a critical load. It will fail. We're pretty sure the building will never experience that load or will experience it only once in a hundred years. But, just to be sure, we make the building two or three (or whatever) times stronger than that.

 

[Gamolon]

I'm no expert (as you know). But this didn't seem right to me because it is my understanding that buildings (and especially the WTC towers) are designed to manage wind loads as whole structures. So I did a little googling, and I'd like to know how you square this with this "Whole Building Design Guide", published by the National Institute of Building Sciences:

https://www.wbdg.org/resources/wind-safety-building-envelope

Do you understand what a "building envelope" is?

https://build.com.au/whats-building-envelope

What's a building envelope?

Climate control
Energy and water management
One term that's used a lot when building a house is 'building envelope'. The concept of a building envelope relates to design and construction of the exterior of the house. A good building envelope involves using exterior wall materials and designs that are climate-appropriate, structurally sound and aesthetically pleasing. These three elements are the key factors in constructing your building envelope. The building envelope of a house consists of its roof, sub floor, exterior doors, windows and of course the exterior walls.

 

[Thomas B]

Do you understand what a "building envelope" is?

Yes, if you read the guide I linked to you'll see that its relationship to the "structural system" is also discussed.

 

[Jeffrey Orling]

Yes, I get that. It's just that I recently lost confidence in your grasp of engineering principles. That's fine. I don't understand them well enough either. Be well.

That's OK...
Most important concept is that every material has what is called ultimate strength. If the stress exceeds that value the material will fail.
So... you have the twin tower floor slabs. Each was the same "design" and construction (except the mech floors which were all the same as well but a bit stronger than the office use floors) and they were designed for loads according to code requirements. So a typical office use would X pounds of super imposed (live) loads per square foot and a warehouse use would be Y pounds of super imposed... and a roof would be Z pounds of super imposed and so on. The ultimate strength (in compression) would be higher than the code value. For example, if code called for a design live load of 50#PSF the ultimate strength of the floor (assembly) would be 125# PSF. The floor would typically have less than 50# PSF. As a floor is loaded it will defect under load. Deflection is another "design" factor. A very stiff floor specification would be deflection less than 1/360 of its span length. More deflection means the floor feels bouncy. A local "overload" condition will usually not fail the entire floor. It may cause a section to deflect more or even "fracture" leaving the remainder of the slab intact.
The runaway floor collapse occurred and was unstoppable when a load exceeded the ultimate strength of the slab (locally)... and then globally (the entire floor footprint). The floor would break apart and drop... If the slab itself had a higher ultimate yield strength than the connection of the beams which supported the slab to the columns... the connections would fail before the slab itself. As the floors were of the same ultimate yield strength... when the mass of a failed floor fell on the one slab below... that slab would of course fail and the process would rapidly repeat and become "runaway" with no possibility for arrest.
The columns are the elements which "convey" the loads of the floors to the foundation. The columns also convey the load from the column above it which rests on its top... and that column is supporting floor loads as well as the column loads on to of it. So loads aggregate and the column ultimate yield strength is increasing from top to bottom. Floor/slab loads are "attached" to the sides of columns in steel frames as the in the WTC. So if and when a floor is overloaded past its ultimate yield strength it will collapse... and the column will no longer carry the load of that floor. The columns cannot play a role in preventing or arresting a floor collapse.... the loads / falling mass simply breaks free and passes them... leaving the columns behind only supporting themselves.
Another important basic engineering principle is that a column of a given length is stronger when laterally braced and weaker when lateral braces are removed. If bracing is removed the column will lose axial capacity and it will buckle... and fail. In the twin tower situation... the floors were collapsing... so the columns were losing capacity... but the columns were also losing the loads.
Incorrect Explanations
Top block crushing the bottom block - The load situation did not change and there was adequate support at any elevation for the section above. The so called crushing would require that the top was laterally displaced and the upper columns move off of axially alignment with those below. What force did could do that? NONE! But if enough columns failed the the remaining ones would buckle, the tops would move laterally and drop and crush the bottom creating the runaway floor collapse.... It would begin with a mutual destruction of the bottom of the top and the top of the bottom.
Correct Explanation
Core columns were losing capacity from the effects of heat. This led to columns buckling and then there was inadequate capacity and the remaining columns buckled and the top dropped... and this led to mutual destruction and the creation of the "ROOSD" mass... outside and inside the core...
We know heat weaken steel. We know heat distorts. warps and lengthens steel. Heat destroyed the strength and integrity of the steel frame. This took place in the core and floor trusses but hardly to the perimeter columns. They buckled from transferred loads and feel away when bracing was destroyed by ROOSD. Over pressure from the air inside being forced away (laterally) by the descending ROOSD mass.. which became like a piston inside the tube driven my the growing mass of collapsed floors.

This is very simple and intuitive to understand.

 

[Thomas B]

You didn't answer my question from before Thomas B. As far as your understanding, when a building surpasses it's factor of safety, does that mean complete collapse?

Of course not, but a threshold for complete collapse (vs. partial collapse or just structural damage that would need repair) are all things that can be calculated, i.e., included in the design. That's all we are talking about.

 

[Jeffrey Orling]

Column free office floor space structures are much more vulnerable to complete collapse than the traditional structural column grid with bays.

 

[Gamolon]

Of course not, but a threshold for complete collapse (vs. partial collapse or just structural damage that would need repair) are all things that can be calculated, i.e., included in the design. That's all we are talking about.

When I asked you "Can you please elaborate on what you believe a "safety margin" is when speaking of buildings?", you responded with the quote below.

What were you referring to when you said "it"?

We know what will happen at a critical load. It will fail. We're pretty sure the building will never experience that load or will experience it only once in a hundred years. But, just to be sure, we make the building two or three (or whatever) times stronger than that.

You also said this:

Not really. I'm not sure what you're driving at. Buildings have a known critical load at which they are expected to fail. But it's usually well above (x 2, 3 ... 5 ... depending on the building) anything they're expected to actually have to face.

What did you mean by "fail"?

 

[Thomas B]

What were you referring to when you said "it"?

The building.

Edit: It might be more precise to say the building design. That is, the structural system is designed to distribute loads to various parts of the building and ultimately to the vertical columns and into the ground. "It" fails if any part of that system breaks under a load (like a hurricane.)

 

[Gamolon]

The building.

Edit: It might be more precise to say the building design. That is, the structural system is designed to distribute loads to various parts of the building and ultimately to the vertical columns and into the ground. "It" fails if any part of that system breaks under a load (like a hurricane.)

Ok, according to you, when the building/building design fails, what happens? What does "fail" mean in this sense?

 

[Thomas B]

What does "fail" mean in this sense?

Sustaining damage under load.

 

[Gamolon]

Sustaining damage under load.

I'm trying to understand what YOU think these terms mean and how they are applied.

If a building's basement sustains water damage, does that mean the entire building's/building's design factor of safety was surpassed? Does that mean the entire building's design failed?