Wood Frame Wind 1

[SteelPE]

I was online today and saw the following video:

https://www.msn.com/en-us/news/other/watch-what-winds-over-100-mph-do-to-this-house/vi-AAsXNpp

It appears as if no hold downs for the roof where used (I'm thinking Simpson H2.5). However, it also appears as if they left some, not all, windows open in the house and I can't but wonder if closing the windows would have not generated the effect the producers were looking for?

 

[MotorCity]

Great video, thanks for sharing. I would be concerned about the damage to the outer building from the roof flying off the house. It conveniently floated out the main building doors without impact. I'd feel better if there were some safety straps or tethers to prevent the flying roof from going too far.

 

[DETstru]

The first test seems pretty silly. There's a perfect joints between the roof and the walls and it doesn't seem like the roof is connected to anything.

 

[SASteve]

The second house, which was tested yesterday, was built to IBHS FORTIFIED specifications (

http://disastersafety.org/clp-demo/).

I'm not sure about the particulars of the first house - the one which lost its roof - but I assume it did not include straps so that they could verify the dispraity in performance between roof fastening methods.

In response to your suggestion that the failures shown in the video were influenced or intentionally staged - you're right and wrong. These experiments weren't constructed just to catch dramatic failures on video, but they are experiments, contructed by researchers with the aim of gathering data. The "producers" piggyback on test day to capture interesting footage, but the actual test lasts several hours leading up to the failures - nobody would be interested in seeing videos of the house at or near its design wind speeds (or at non-critical wind angles) because that part is pretty boring visually.

I heard through the wind engineering grapevine that the second house withstood far greater winds than expected - a testament to the "FORTIFIED" standards - but I assume that the wall failure that you saw was not what the team actually wanted to see from a data acquisition perspective. Following the planned tests, which weren't dramatic enough for the media to report on, the structure was rotated so that the garage door opening was windward. This would have, as you suggested, influenced the failure.

Also, as you pointed out, the case with windows open/closed are both important, but it is well-understood that windows, doors, and garage doors usually go first due to either debris or high wind speeds, and that these failures lead to internal pressurzation. Now, we need to understand what the next-weakest link is under these conditions. The way to do this is to leave windows and doors open stategically.

The most interesting takeaway from the video, scientifically, is that the second house failed at wind speed "well over" 100mph.

 

[SASteve]

MotorCity: Outside of those large doors on the outer building IBHS has several miles of land cleared to allow for debris to exit and come to rest safely, away from all of the expensive equipment.

 

[SteelPE]

SASteve, so in regards to the second house, what happened to the garage door, was it left open or was it blow away by the earlier portion of the test?

I understand that seeing an intact house is not really interesting, but nowhere in the video did they say that they were intentionally trying to destroy the house. All the video says is that the wind is over 100mph (which is a wind speed that exceeds the design wind speed in 90% of the continental US according to ASCE7). Now if Joe Public sees this video they are not going to understand what is happening (other than seeing a house being destroyed from by wind). I think the presentation is very poor.

 

[SASteve]

From what I understand the house was angled so that the garage door would blow in, which happened shortly before that wall started to come off.

I agree, the representation by the media often isn't great (Aside: For example, media reports of damage from Hurricane Irma led us to expect damage far more severe than we saw in post-storm damage surveys. This can become dangerous - when the public sees only the worst-case failures in neighboring towns on TV, it may lead to them to believe that their own homes are "bulletproof" and become complacent in preparing for the next storm.. while in reality the storm wasn't as destructive as portrayed.) This may be due to lack of technical understanding more than "fear-mongering", which was not what I intended to suggest.

Some recent research has focused on exploring the public "risk attitude" towards adopting reslience-boosting measures. It's an interesitng socialogic problem as well as an engineering one.

It's hard to catch/retain public interest with science, so in that sense the media does it's job by turning people towards the work being done. I hope it leads some to do more research about what is actually under investigation during these massive tests. I expect that upcoming releases by IBHS will be much more informative.