Re: [Phys-L] measuring hurricane strength

[John Denker <jsd@av8n.com>]

On 09/06/2017 11:38 AM, Folkerts, Timothy J wrote:

> "According to Robert Simpson, there are no reasons for a Category 6
> on the Saffir-Simpson Scale because it is designed to measure the
> potential damage of a hurricane to man-made structures. Simpson
> stated that "...when you get up into winds in excess of 155 mph (249
> km/h) you have enough damage if that extreme wind sustains itself for
> as much as six seconds on a building it's going to cause rupturing
> damages that are serious no matter how well it's engineered.""

That doesn't change the physics.  It is straightforward to
engineer a structure that could withstand winds of 157 mph
but not 185.  Maybe Simpson couldn't imagine such a thing,
but I certainly can.

This is relevant to places like, oh, say, Houston, where they
do not have a plan for evacuating the city as a whole;  they
tried that in 2005 and it was a fiasco, and nowadays they don't
even try.  Instead the most they can do is relocate people to
shelters /within/ the city, so if you assume destruction of
*all* structures you're begging for trouble.

Reliability engineering is a long-established engineering discipline.
The number of people who know how to do it properly is rather small,
but the good guys are very, very good.  You can see this in e.g.
the phenomenal reliability of airliners.  You can see the lack of
it in the toxic explosions at the Arkema plant near Houston.  They
had chemicals that needed to be kept cool.
  -- Plan A was to use power from the local utility.
   That failed due to the flood.
  -- Plan B was to use on-site backup generators.
   That failed due to the flood *and* the lack of proper analysis.
  -- Plan C was to use portable refrigerated storage units.
   That failed due to the flood *and* the lack of proper analysis.
  -- Plan D was to burn off the chemicals before they could explode.
   That failed because the staff evacuated on account of the flood,
   *and* because of the lack of proper analysis.
  -- etc. etc. etc.

You can sing the same song about the Fukushima meltdown.  It's
gross engineering malpractice.  You would think that anybody
with more than a one-digit IQ would realize that your backup
plans ought not exhibit failures that are correlated with
your original plan.