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Earthquake resistance: Linear, or not...?

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Earthquake resistance: Linear, or not...? Kris Krieger 03-07-2008
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Posted by ++ on March 13, 2008, 11:44 pm


Kris Krieger wrote:

>
>
>
>>.
>>
>>
>>>
>>>
>>>>The word that you are looking for is Ductility not flexibility.
>>>>Such as a
>>>>ductile moment frame. Hope this answers the question.
>>>>
>>>>
>>>Sorry, Chuck but this thread is on earthquakes - the AC duct
>>>relocation question is a couple threads over. ;)
>>>
>>>Don is always looking for a word - and he's going to use every word
>>>he knows until he finds it. =:O
>>>
>>>R
>>>
>>>
>>Both ya'll need to pay attention, I didn't use either of those words,
>>I think Kris did, about bones.
>>
>>
>
>Yup, I did. Bones are felxible. Wood is flexible.
>
>
>Flexible = able to bend without incurring damage
>
>Ductible = capable of being drawn out
>
>A spring is flexible. The metal that is drawn out to create the wire used
>to make the spring is ductible.
>
>
>
>>But yeah, if Cuse manages to move that thing successfully it could be
>>said he has ductibility. =D
>>
>>
>>
>
>Or, living near all tat wter in Miami, maybe "ducktability" ;)
>
>

Or may plasticity, since you live in America

>
>
>
>


Posted by Kris Krieger on March 16, 2008, 1:28 pm

>
>
> Kris Krieger wrote:
>
>>
>>
>>
>>>. .
>>>
>>>
>>>>
>>>>
>>>>>The word that you are looking for is Ductility not flexibility.
>>>>>Such as a
>>>>>ductile moment frame. Hope this answers the question.
>>>>>
>>>>>
>>>>Sorry, Chuck but this thread is on earthquakes - the AC duct
>>>>relocation question is a couple threads over. ;)
>>>>
>>>>Don is always looking for a word - and he's going to use every word
>>>>he knows until he finds it. =:O
>>>>
>>>>R
>>>>
>>>>
>>>Both ya'll need to pay attention, I didn't use either of those words,
>>>I think Kris did, about bones.
>>>
>>>
>>
>>Yup, I did. Bones are felxible. Wood is flexible.
>>
>>
>>Flexible = able to bend without incurring damage
>>
>>Ductible = capable of being drawn out
>>
>>A spring is flexible. The metal that is drawn out to create the wire
>>used to make the spring is ductible.
>>
>>
>>
>>>But yeah, if Cuse manages to move that thing successfully it could be
>>>said he has ductibility. =D
>>>
>>>
>>>
>>
>>Or, living near all tat wter in Miami, maybe "ducktability" ;)
>>
>>
>
> Or may plasticity, since you live in America
>

THat'd be Plasti City =:-o




Posted by Kris Krieger on March 16, 2008, 1:27 pm

>
>>
>>>
>>> .. .
>>>>>
>>>>> The word that you are looking for is Ductility not flexibility.
>>>>> Such as a
>>>>> ductile moment frame. Hope this answers the question.
>>>>
>>>> Sorry, Chuck but this thread is on earthquakes - the AC duct
>>>> relocation question is a couple threads over. ;)
>>>>
>>>> Don is always looking for a word - and he's going to use every word
>>>> he knows until he finds it. =:O
>>>>
>>>> R
>>>
>>> Both ya'll need to pay attention, I didn't use either of those
>>> words, I think Kris did, about bones.
>>
>> Yup, I did. Bones are felxible. Wood is flexible.
>>
>>
>> Flexible = able to bend without incurring damage
>>
>> Ductible = capable of being drawn out
>>
>> A spring is flexible. The metal that is drawn out to create the wire
>> used to make the spring is ductible.
>>
>>> But yeah, if Cuse manages to move that thing successfully it could
>>> be said he has ductibility. =D
>>>
>>
>> Or, living near all tat wter in Miami, maybe "ducktability" ;)
>
> I moved a duct today and used the method Rico said, I moved it
> upstream about 2 feet.

See, "stream", "duck"... I see a pattern emerging here...

;)

> I used *duct* tape to seal it against the register then I put a giant
> zip tie over the whole mess.
> Believe it or not this house has heat-AC registers in the floor, and
> the one in question was right where you will step out of the new
> shower, so it had to go.

Our house in Massachusetts has floor registers; I don't think it's all
that uncommon "up north", since it's harder to force heat downwards to
the floor, and not as critical to force air-conditioning upwards.

OTOH, they also collect stuff that way, and air-flow can be problematic
so I ended up making duct-covers so as to direct airflow better, and
reduce the amount of stuff that'd get into them.

> I was going to originally move it up high on the wall but the actual
> doing was much more than I could deal with.

I can imagine what a PITA it could be, after watching the original
ducting being installed in our place.

(OK, let's be honest, I just dislike forced-air gas heat...)

Posted by Kris Krieger on March 13, 2008, 4:13 pm

>
>>
>>>
>>>>
>>>>>
>>> [Edited]
>>>
>>>>> As far as earthquake stuff goes, my knowledge is
>>>>>> limited to general science stuff I've seen on the toob but I
>>>>>> believe flexibility is the key.
>>>>>
>>>>> Felxibility, yup, that does seem to be a main, or poss. *the*
>>>>> main, point. I saw one thing (let's face it, if thre is somehting
>>>>> on about earthquakes, i watch it...) which showed buildings in
>>>>> Turkey - new houses that were monolithing construction
>>>>> (cinderblock) fell apart, btu traditional houses, which started
>>>>> with timber frames taht included diagonal supports (not so
>>>>> differnt from old ENglish half-timber methods), which then were
>>>>> filled in with bricks, remained standing, with only a rew
>>>>> exceptions.
>>>>>
>>>>> Your point re: the trusses is also a good one. So, yup, it seems
>>>>> that a building has to be a *system* to survive unusual
>>>>> conditions, as opposed to merely being a collection of disparate
>>>>> parts...
>>>>>
>>>>> Let's hear it for cells (as in the biological/living things) ;)
>>>>>
>>>>> Actually, only half a joke - are you catching any of the new
>>>>> series about the Body?
>>>>
>>>> No, but I'm going to.
>>>> (short story: My wife and I have gotten into the habit of watching
>>>> that show, 'How It's Made' on Discovery while eating supper and
>>>> invariably they'll show a commercial about 'The Body' and eveytime
>>>> they do I say, 'One of these days I'm gonna watch that show'. Its
>>>> sort of a joke. So far I haven't watched it. We don't watch much.)
>>>
>>> Both are intresting, although sometimes the "how it's made" topics
>>> are less interesting to me than teh biology-related things - such
>>> as, I wasn't fascinated with how pencil erasers are made ;)
>>> Mechanical topics are interesting, tho'.
>>>
>>>>> Last week, they discussed bones, and the high degree to which
>>>>> bones are cellular is structure (as opposed tosolid) and
>>>>> *flexible* - it was maazing to see how far a bone could bend
>>>>> before failing (breaking). Biology has had millions of years to
>>>>> "experiment" and offers intersting examples. Makes me wonder
>>>>> whether,a t some point, we'll be able to *grow* buildings -
>>>>> although that's an entirely different topic.
>>>>
>>>> According to Per Corel that exactly how its going to happen, sort
>>>> of. He envisions his 3DH buildings constructed at the molecular
>>>> level by microscopic robots and after a building is completed the
>>>> robots will be reprogrammed to perform constant maintenance.
>>>
>>> THe problem is that I never could get a handle on what "3DH"
>>> actually *means*. I also never caught the bit about the
>>> mini-robots, either, so thanks for pointing that out... I had a
>>> hard time understanding the explanations. I looked at the pics of
>>> models, but i guess I didn't get out of them what was intended...
>>>
>>> Anyway, re: "grow buildings", I mean, biologically, not using
>>> robots. More along the lines of breeding a tree, for example, that
>>> stays under a certan height, and grows in a way that creates hollow
>>> chambers. Not even my own idea, really, but somehting I came across
>>> in a "scifi" novel.
>>>
>>>
>>>>> Meanwhile, the interactions between materials, and structures, and
>>>>> the resulting resistance to stresses, is an interesting thing.
>>>>> I'm thinking that the "weaklink" in wooden structures, as far as
>>>>> earthquake resistance goes, might be the nails, since wood itself
>>>>> seems far superior. SO I'm wondering whether it'd be "sturdier"
>>>>> (to use the term a bit inaccurately but hopefully the meaning is
>>>>> clear) to use fitted joints, as were used in the "pre-nails"
>>>>> days...?
>>>>
>>>> Here's a prediction, which I originally predicted some 10 years
>>>> ago. Under the right conditions the wood trusses will fail because
>>>> the number of nails required will effect the stability of it.
>>>
>>> Not surprising - the strength and flexibility of wood, like that of
>>> bone, is not a funciton merely of the existence of verious types of
>>> cells and "biological glue" so to speak, it's a funciton of the
>>> *interconnectedness* of the cells and any other materials. THink
>>> abotu the qualities of cartelege, and then think what would happen
>>> if it were punched full of holes. People think of wood as "hard",
>>> more than they think of it as "flexible", and same is true of bone.
>>> But part of the strength *is* the flexibility, and that flexibility
>>> is comprimised once the material is made discontiguous so to speak.
>>>
>>>> Right now, something like 18 nails are *required* at each
>>>> truss/hurricane anchor and to me that many holes in the wood isn't
>>>> a good thing. Ever seen a piece of wood with 18 nails in close
>>>> proximity? It ain't pretty - the wood is horribly splintered.
>>>
>>> Yes, and true.
>>>
>>>> I'd rather see 12 guage angle steel reheaded into the top/side of
>>>> the concrete tiebeam and through bolted through the truss heels -
>>>> the angle steel would go up and over the top chord and be bolted
>>>> from both sides. This would be less strain on the wood in the
>>>> truss. The plywood roof sheathing, not OSB, 3/4" plywood, would be
>>>> installed with #12 x 3" screws @ 8" o/c along the perimeters of the
>>>> sheets and all plywood seams would receive 2x4 deadwood. These
>>>> things would add about 15-20% to the cost of the roof but would add
>>>> considerably to the overall integrity of it. **No inspector is ever
>>>> going to count all the nails in every hurricane anchor on every
>>>> house.
>>>
>>> Hmm. Interesting idea. I'm saving that one.
>>>
>>> ((Isn't the largest cost of most houses actually the land, rather
>>> than the structure...?))
>>
>> Probably the most expensive single piece of land I've been involved
>> with was $850k for less than 1/4 acre on Useppa Island and the house
>> that was built on it was valued at over $2 mil.
>> Most of the stuff I've done was a far less ratio.
>> My own property in the Cape cost $3500 in 2001 for 1/4 acre and in
>> 2006 I sold it with a house on it for $300k and the original cost of
>> the house was $155k + add-ons.
>>
>
> The word that you are looking for is Ductility not flexibility. Such
> as a ductile moment frame. Hope this answers the question.
>
> CID...
>
>

I though "ductile" meant "can be drawn out/extruded"?


Posted by ++ on March 8, 2008, 12:13 am


Kris Krieger wrote:

>>>>
>>>>
>>>I know the Richter scale is exponential, but I'm still wondering
>>>whether a structure builkt to withstand X.Y fails at X.Y+1. So, they
>>>aer currently retrofitting the Golden Gate Bridge to withstand
>>>soemthng like 8.3, but does that mean it will fail (i.e.
>>>disintegrate) at 8.4, or what?
>>>
>>>
>>Can't be done, except in a computer model, cause there's too many
>>variables. First, you have to define *failure* then design around that
>>parameter. In SW FL for example the homes I design are supposed to
>>sustain a 130 to 150 mph wind and usually they do.
>>But that doesn't mean things won't fail.
>>
>>
>
>SO, if it's designed to withstand 150mph, and a 160mph wind occurs, the
>whole thing simply disintegrates instantly...?
>
>What I'm trying to figure is, if people are in a bldg (house, highrise,
>whatever) rates to withstand X.Y, but a quake of X.y+1 occurs, does the
>bldg just completely disintegrate/implode into shards at that point and
>kill everyone inside?
>
>

The answer is that the failure is not necessarily so. Building do not
normally implode without controlled explosions. the design itself can
mitigate against specific failures as you suggest with your wind example
below. One resource, partially paid for with your taxes:
http://www.bssconline.org/

>
>
>
>>On my own house, it went through several hurricanes but some things
>>did fail, though nothing structural.
>>If any of those hurricanes would have stalled on my house there very
>>well may have been structural failure.
>>Some of the soffit tore loose, a design flaw (which was later
>>corrected), that allowed wind to penetrate the envelope.
>>If this wind would have sustained it may have lifted that portion of
>>the roof and once that happens its all over.
>>(I installed more, and longer, nails along the edge of the fascia that
>>attaches the soffit and used 24 tubes of silicone caulk to secure the
>>soffit to the stucco wall and fascia. This had the added benefit of
>>thwarting the yellow jackets from nesting in the valleys of the
>>soffit) Regarding the Golden Gate, what did they do, put it on pulleys
>>so it'll sway like a pendelum?
>>
>>
>
>I couldn't really teel from the program - in many areas, it looks like
>they're reinforcing it, but I don't knw whether other areas might be put
>onto rubber "floats" - I couldn't tell. But San Francisco (IIRC) has
>been literally lifted and placed onto rubber plugs that are supposed to
>absorb the shaking. THey also described the swaying that some wooden
>houses can withstand.
>
>So that's what all got me wondering about building for earthquake
>resistance, and what the limits of that are.
>
>I'm not sure I asked the question properly, either.
>
>

happy reading. in the links below:

http://www.bssconline.org/links.html

For your own hazards related calculations there are several FEMA tools
and you can even get free training in them.

>
>
>
>


Page 4 of 9       < 1 2 3 > last >>
Similar ThreadsPosted
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