I was watching something about earthquakes and building (or retrofitting)
for earthquake resistance. I'm assuming it's a "curved graph", but maybe
not? So I was wondering, if something is made to survive an earquake of
X.Y , would it fail catstrophically at X.Y+1, or would damage increased in
a way that'd be mroe of a cruved line of a graph...? I'd assuem teh
latter, but what seems logical, isn't always how things work.
Also, if a cinderblock house can be made earthquake-resistant by running
rebar through the spaces and backfilling with concrete or whatever, would
that also work for brick (since at least some bricks now are cellular
rather than solid)?
And, is there special morter? IOW, would ti be an acrylic-based moreter or
some other type of elastic base material?
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?
I'd Google it but don't know how to frame the inquiry properly.
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?
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.
You're asking a question that can't be answered simply. You'd design
a building for 150 mph winds, but there are factors of safety
involved. The probability that a failure will occur with a wind
higher than the design load increases but it's not linear, it's not
simple and it's often times not calculable. The only way to test it
would be to overload it to destruction.
There are localized conditions and unforeseeable benefits and
disadvantages that help or hinder the chances of a buildings
survival. The surrounding terrain could help or hurt, for instance.
The design might have been based solely on nailed sheathing and the
cowboy with the nailgun might have missed the studs with a bunch of
nails. These things are not included in design calculations. A
building might withstand a wind load 50 percent higher than the design
load, or it might fail at or below the design load due to unaccounted
for variables, faulty calculations and assumptions, or poor
So, I guess what I'm saying is make sure your insurance is paid
So then how can anyone actually say at all that a bldg can withstand this
or that strength earthquake, if any/all would pancake unpredictably? I
think I'm more confused now than I was before...
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
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? 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.
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...?
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'.
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.
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.
Yes, and true.
Hmm. Interesting idea. I'm saving that one.
((Isn't the largest cost of most houses actually the land, rather than
I don't mean "valued" (evaluation), I mean, straight cost to build. OTOH
I admittedly have no contact with the work of $2-mill-+ properties (or
even $1+ mil, for that matter...)
That's it, what you can get for $X thousand (of house - i.e. not
including property) is, from what I have been able to find, rather
superior in quality to what you could get for the same money in a
developer-built place, mostly becasue developers tend to go for size
rather than quality - but that's just my impression, because I've never
been able to dig up the hard numbers.
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
Ductility is a term for the behavior of the structure by letting it yield
during a eartquake and go back when the quake is over. Look up the
defination in a dictionary for the word ductility. It is not reference to AC
ducts in this case. Oh well, I will do it for you.
1. capable of being hammered out thin, as certain metals; malleable.
2. able to undergo change of form without breaking.
Now Don knows it also.
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.
Or, living near all tat wter in Miami, maybe "ducktability" ;)
See, "stream", "duck"... I see a pattern emerging here...
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 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...)
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:
happy reading. in the links below:
For your own hazards related calculations there are several FEMA tools
and you can even get free training in them.
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