Matt Whiting wrote in
:
Kris Krieger wrote:
Matt Whiting wrote in
:
Anyone can build something 10X stronger than it needs to be. An
engineer's job is to balance strength against economics.
I keep thinking of the program I saw on the Discovery Channel about
tornadoes - they showed one neighborhood (no basements of course)
where every house had been flattened and the population was decimated
- except for one guy and his family; he'd had a reinforced shelter
installed in the center of the house, and that shelter was the only
thing left standing, and he and his family were the only people left
without some sort of injury.
So, if something is "overengineered", but is left unscathed, or at
least with only minimal damage, when that supposedly 100-year storm
hits, is it actually over-engineered, or is it correctly engineered?
It depends on the owner's requirements. If the owner asked for a
house that could withstand an F5 tornado, and the house was just
strong enough to do that, then it was correctly engineered.
However, engineering requires balancing capability vs. cost. I can
design a house that will withstand pretty much any storm or hurricane
imaginable, but it would cost a fortune. Engineering is the art and
science of designing something that meets the stated requirements with
the minimum consumption of material and money.
Yup, that's why I thing the term "overengineered" is largely a matter of
perspective. In addition to, as you'd noted, capability and cost,
another consideration is how the person lives. If someone only needs,
say, a 700 sq ft space from their living needs, he can put more money
into making a strong structure.
I think the problems arise when the appearance of luxury takes precedence
over the capability of the structure to withstand fully-predictable, if
relatively uncommon, circumstances.
For example, it's fully predictable that, eventually, a hurricane of
another tropical storm along the lines of Allison will strike the Texas
coast, yet development after development has been built on land that is
barely a foot above sea level, and the places are not built all that
sturdily.
If I lived in a tornado-prone area, well, I don't know what would be
required to give a house a reasonable chance of at least protecting the
residents, but I'd certainly *like* to know, would like to see diagrams
and a cost-comparison between it, and a "regular" house, plus a
comparison of long-term costs (for insurance and so on).
It seems to me that the "minimum code" is just that. Minimum.
Unfortunately, nature doesn't pay much attention to statistics, and
storms are tending to get stronger, not weaker. So personally, I'd
prefer to pay more for something that is "over-engineered", and did
pay extra for things like Tech-Shield and Tyvek.
You are confusing over-built with over-engineered. They are different
concepts. It actually takes a lot more engineering to make a
structure as I described above - one that balances optimally
performance vs. cost.
Maybe, but I didn't see the phrase 'over-built' previously in the thread,
and to be honest, I always thought the phrase meant more along the liines
of having lots of accoutrements and flourishes and so on. IOW, things
that don't add to the strength of the actual structure.
My example was only to illustrate that I personally would happliy willing
to buy a smaller place with more storm-resistance and more energy-
efficiency. I know that most peole want size because most value flash
more than substance (such as the place one real estate agent showed us -
the master closet alone was *literally* very near to the size of the
townhouse we'd rented in California).
Designing something that far exceeds the required performance with
little regard to cost is actually much easier from an engineering
perspective.
I'd guess so!
Most people - well, most people just hink about what's cheap today,
not about what will cost less over a few years or even what will be
safer if a severe storm hits.
That isn't an engineering decision, however. That is a requirements
setting decision made by the person footing the bill.
Every year, without fail, we see news reports about "sufficiently
engineered" homes destroyed by natural events that are *known* to
have occured in their given areas, hence are a known risk. On
average, those non-average conditions are called "statistically
insignificant", and engineers are called upon to do their
calcualtions and plans accordingly - they're given a certain set of
parameters and a certain budget, and told to stay within those,
regardless of whether or not they might think it unwise to stay only
withing the minimum/code. So, IMO, much of what gets called
"overengineering" is actually "engineered to withstand a wider range
of conditions than those which occur on average".
Engineering isn't the art and science of making indestructible
structures. That is my point.
I understand, it's just that it seems to me that too many places are
built jsut well enough to stand for 10 years, and only if statistics hold
and no severe storm hits.
I'm admittedly not separating what the engineers do, from what the
designers do and what (with development corporations) the marketing
people do. Mostly, I guess I'm saying that the engineers probably should
have a larger say in the matter, because marketers will always go for
"pizzaz" and designers, like the engineers, are at the mercy of the
financiers and marketers. OTOH, a good designer will look more at
whether a design is not merely huge, but actually liveable, and a good
engineer will look more at the strength, integrity, efficiency of HVAC
systems, insulation, and weather-resistance of the structure.
So, to use an analogy, if you have 2 houses on same size lots, next door
to each other, and both costing $250K, IOW built using the same bottom-
line budget maximum. The "normal" one will have more square footage,
might have more expensive lighting fixtures, fancier cabinets, granite
countertops, and so on - whereas the one that might be called "over-
engineered" would have less square footage, Corian or Silestone
countertops, plainer cabinets, basic lighting, and the like, but might
have, for example, doubled brick facing or might be of puured concrete,
or so on, that would be able to block most debris that would be whipped
around by hurricane-force winds.
If that's not what is meant by the term, sorry and please informe me of
the correct useage, so that I know for future reference - I mean that
honestly
.
- K.