Natural disasters, earthquakes, floods, massive heavy rain, wind pressure, hurricane – how can you protect yourself?
We are experiencing increasing reports about natural disasters such as earthquakes, hurricanes and floods. As a result, engineers and investors are more and more consious of these topics when planning new projects.
From the point of view of a calculation engineer, these issues can be viewed in advance and secured in a reasonable framework.
Stricter regulations only make sense if they are really necessary.
Merkle & Partner has been dealing with the individual issues intensively for decades. In the following, I briefly describe which topics and tasks we are addressing in this series of articles.
On March 11, 2011, a magnitude 9 earthquake shook the coast of Japan. The epicenter was off the east coast and the quake produced a massive tsunami. Waves as high as 40 meters roaring toward the coast. More than 18,000 people died. Whole cities were wiped out.
In the Fukushima-Daiichi nuclear power plant the electricity went out. The lack of cooling led to a meltdown after the accident.
As a result, the requirements for seismic resistance of nuclear power plants were in some cases considerably tightened.
We think that earthquakes are more likely to occur more frequently than before, but the impression is deceptive. What has changed is the frequency of media coverage.
Image 1: Fukushima after the earthquake
Earthquakes belong to earth. Our job is to minimize the resulting damage.
But how can buildings and facilities be made safer against the effects of earthquakes and how can you calculate that?
It is easy to imagine that wind velocity of 250 km/h, as found in cyclones, are a significant burden on buildings and components.
Image 2: Tacoma Bridge 1940
But also moderate constant wind velocity is a danger, and this is precisely when periodically detaching vortices lead to an agitation of natural frequencies.
The classic example of this is the collapse of the Tacoma Narrows Bridge in 1940.
Image 3: Marilyn
The wind velocity of comparatively moderate 68 km/h led to a vortex agitation of the natural frequency of 25 Hz, which then resulted in the collapse of the bridge.
But even the influence of gusts of wind can lead to short-term liabilities. Even if these are sometimes only of a psychological nature. The picture (image 3) is one of my favorites and hangs in my office, unfortunately not in the original.
How can one look at and secure wind pressure by calculation?
Floods and heavy rain
In addition to a tsunami, in which a wall of water rushes to the shore due to a seaquake, heavy rains and hail can cause the soil and sewer systems to no longer absorb the water masses. Thus landscapes and buildings are flooded.
Image 4: Vehivles flushed off the street
As a child, I witnessed such an incident when my hometown Heidenheim experienced the worst weather disaster on 29th of August 1968.
At about 10 pm on that Thursday evening, the elements raged for about one and a half hours. Our house was on a slope and suddenly became the shore of a traveling stream. I still remember my dad in his nightgown in our Klepper foalding boat coming to the aid of people on the street.
Again, simulations can help find solutions to minimize the effects of flooding. When we calculate wading depth of vehicles, we do the same.
To find out more about natural catastrophes, earthquakes, floods, massive heavy rain, wind pressures or hurricanes, read our next series of articles or talk to us directly.
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Yours Stefan Merkle
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