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definition of COLLAPSE
4

definition of COLLAPSE

definition of COLLAPSE

(OP)
Recently I was asked to define "collapse" relative to a structure, or portion of a structure.

After some thought, I stated that a "collapse" is a condition in which a structural member has so little integrity (for whatever reason) that it will undergo a "catastrophic collapse" when subjected to only a small portion of the load that it is intended to support.  I continued, by defining a "catastrophic collapse" as a condition in which a structural member has actually deformed, deflected, or moved so significantly, that even a lay person would know to avoid it.

The party that asked the question, seemed uncomfortable with my response, implying that a member must have already deformed, deflected or moved significantly to be considered as a “collapse”.   I considered my response to be from the viewpoint of a structural engineer, and his belief to be that of a non-engineer.

I am curious to see what other engineers believe relative to this definition.

RE: definition of COLLAPSE

i think you've overcomplicated the question.

picture a house of cards.

now, picture a bunch of cards lying of the ground.

that would be a collapsed house of cards !

a component in a structure may well deform before failing.  the structure may well continue to carry load, albeit deflected, or it may "collapse"

RE: definition of COLLAPSE

I would interpret your definition as a structural "failure", rather than a "collapse".

cheers

RE: definition of COLLAPSE

epr

This is a very interesting question that I am asked about quite frequently in a legal arena, usually with an attorney in pursuit of assigning blame.

I don’t agree with your philosophical difference between your version of ‘collapse’ and ‘catastrophic collapse’.  A structural collapse is an event that occurs resulting in a structural member being overloaded or severely compromised past it’s limit resulting in severe deformation or buckling to where the member is significantly out of position.

An example from one of my current cases:  Several joists of a wood-framed house with a low-sloped roof were severely decayed, presumably caused by decades of ponding, cyclic deformation and water infiltration.  The joists in question were so deflected and eroded by decay that they lost their ability to support the roof loads.  However right below them were non-load bearing, full-height cabinets that acted as partitions between children’s bedrooms.  Instead of collapsing right away, these joists rested on the cabinets for an unknown period of time.

The contractor hired to do a remodel when the children were grown began to remove the cabinets, triggering the ultimate collapse of the roof.  In this case, the structural members had failed, but had not yet collapsed.  It becomes a point of contention between the various defendants, plaintiff and insurance carrier, of who caused the collapse.

Say you have one column amongst many that is defective for whatever reason, resulting in lateral-torsional buckling.  But it just twists and deforms and the load is distributed to surrounding columns without any roof or floor collapse.  Yes, there has been a structural failure, but no collapse.

I say something pretty much has to fall down before I’d call it a collapse.  The difference between collapse and catastrophic collaspe is one of magnitude, and economic impact.

"If you are going to walk on thin ice, you might as well dance!"

RE: definition of COLLAPSE

But, a fallen house of cards, and a fallen building, will, after failure, support a load substantially greater than that for which they were originally intended.

The first thing that came to my mind was 'gross deformation'.

The second thing that came to my mind was Google.
A search for [<word> define] will net you dictionary entries for <word>, including that from dictionary.net, which for "collapse" boils down to "sudden and complete failure".

I hadn't thought of the time element, because stuff has usually stopped falling when I reach the scene, but I think it's an important part of the word's meaning.

Mike Halloran
Pembroke Pines, FL, USA

RE: definition of COLLAPSE

I would call a structure whose members are no longer able to support a load to be "compromised" rather than collapsed.

RE: definition of COLLAPSE

Collapse means a structural element fell to the ground or to the level below.  I like the house of cards analogy.  You can have a total collapse or a local collapse.

Significant structural failure may occur without collapse such as buckling of members, connection fracture, excessive deflection/deformation etc.

You can have components of buildings such as ceilings, partition walls etc fall to the floor.  These are considered damage but not structural collapse.

RE: definition of COLLAPSE

2
"collapse" - you need to scrape it up off the ground in a front loader

KENAT, probably the least qualified checker you'll ever meet...

RE: definition of COLLAPSE

I would contend that a colapse does not have to be dramatically evident to have occurred.
A roof may collapse onto the ceiling joists, or it may break through that to rest on the floor, or through that to rest on the ground.
It would not be how far it fell that indicated the collapse but that designed support was no longer supporting the load.

In the case Cass put foward, "Instead of collapsing right away, these joists rested on the cabinets for an unknown period of time." My contention would be that the collapse had already occurred, whether by millimeters of feet, the members were no longer supporting the load; as was evident by the fact that when the cabinets they had collapsed onto were removed they continued the falling that had already started, and which had been temporarily arrested by the cabinets.

Of course I am no structural engineer, nor legal expert, but logic would indicate to me that a collapse is not a matter of degree, but an event that takes place when a breaking point is reached, the straw that broke the camels' back.

Running back to hide in my box now!

RE: definition of COLLAPSE

Collapse can occur at the time of failure or later.  Failure can occur without collapse if there is another load path, redundancy, or ductility.

RE: definition of COLLAPSE

(OP)
Thanks everyone, your responses are interesting and well thought out.

Now, would anyone like to start a thread regarding the definition of "unsafe", as it relates to a structure?  
This is another word that should have a variety of answers, even from the engineering community.  And by the way, citing the building code definition of "unsafe" would be a cop out.

RE: definition of COLLAPSE

Cracking reply Ken

Kevin

“It is a mathematical fact that fifty percent of all doctors graduate in the bottom half of their class." ~Author Unknown

"If two wrongs don't make a right, try three." ~Author Unknown

RE: definition of COLLAPSE

Shaman2,

Here's a good photo of a sheathing failure of a roof from my current case file.  In this particular situation, the sheathing wasn't described as collapsed because the mastic on the roof shingles was holding what was left of it up. Rarely is the situation you describe called a 'collapse'.  It's too big of a word and implies a dramatic event.

"If you are going to walk on thin ice, you might as well dance!"

RE: definition of COLLAPSE

Thanks Cass.

I would agree on the pic above because what is holding it together is still part of the building. In the prior case I am picturing the cabinets as freestanding furniture instead of being part of the building. Thus I would have said it had collapsed onto the furniture, whether the furniture was full hight or three foot high, under the definition that to collapse is to give way. However I note several other definitions( in Mirriam Webster) require the collapse to be sudden, and who knows how suddenly the joists fell to the top of the full height cabinets. Did in happwn as slow deflection over years, or suddenly one night when a storm was shuddering the house.
At any rate I appreciate the information. While I am nether a structural engineer nor a lawyer, I still like learning all I can about what is going on out there, in every field.

 

RE: definition of COLLAPSE

This is an apse roof



casseopeia image is an out o apse roof so it is a roof in collapse

cheers

Luis

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