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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"?
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