Weather

[japhy]

I heard from Shirley last iight after the eye passed over them in Sarasota and then again this earlier AM. His daughter's house made it and everyone is safe.

[KUTradition]

seriously, thanks for the update!

[pdub]

Good news for Shirley.
Thanks japh.

[KUTradition]

a florida record, 100+ tornado WARNINGS yesterday

[KUTradition]

i was in Daytona when Charlie hit 20 years ago

unforgettable

[jhawks99]

Glad Shirley and his family are safe.

[TDub]

glad thr good doc is ok

[japhy]

Things to keep in mind about wind. The force exerted is proportional to the wind speed, squared.

So 100 mph winds exert a basic wind force of around 25 psf. In a lot of cases this is a default value for design. 140 mph winds exert a force of around 50 psf. Florida got lucky when the wind dropped that 40 mph at landfall. The 140 mph number is a basic design wind speed in many coastal areas.

What that translates into lateral force on a small house with a 16'x60' horizontal profile is V100=24,000lbs versus V140 =48,000 lbs of base shear. How that is resisted is by the two end walls of the house which are parallel to the wind force, in shear between the bottom plate of the frame wall to the foundation through anchor bolts.

Using simple numbers, assume the house is 24 wide and has a double bearing plate on the bottom of the wall. The shear at the top of the end foundation walls is v100=500 plf, with a capacity off around 1000 lbs/anchor you would want an anchor bolt every 24 inches. With v140=1000 plf you would have anchors spaced at 12 inches oc, closer than the studs. This is why special anchors should be used in Florida instead of simple anchor bolts

Next time there is a big wind in your area and a house blows off the foundation, look at the top of the foundation wall. Anchor bolts do not pull out of the concrete wall, they split the wood and pull through the bearing plate. Usually there are little to no anchors bolts showing in the wall. The news will talk about how "incredible" it is that one house is destroyed and the house on either side is not. "Must have been a microburst!" It's not weird, it is predictable and would be expected.

A house using only "Code minimum" anchors can blow off a foundation in 80 mph winds.

"Code minimum", a house builder's best friend, it usually says an anchor every 48 inches unless otherwise determined otherwise by analysis. Engineering analysis is not required by Code. Code officials will approve the 48 inch spacing during inspections and plan review. The reality is that if you follow Code design forces down to the foundation through analysis, you likely need twice that many.

Go down in your basement some day and look at the top of your foundation walls and see how many anchor bolts are in the bearing plate on top of the wall. Better yet, look at this in the basement before you buy a house.

After these last two hurricanes you will notice towns quietly updating their "adopted building codes". Each Code update increases wind and snow loads. Each update gets push back from the construction industry because it makes "houses more expensive". So the city will delay, sometimes indefinitely adopting an updated Code. Did you know that Parishes in Louisiana were still governed by the 1946 Southern Building Code well into the 1990's? Some of the delays probably cost people their homes in these events, and insurance costs rise, making "houses more expensive". If you pay up front it will save you in the long run.

[Back2Lawrence]

I heard from Shirley last iight after the eye passed over them in Sarasota and then again this earlier AM. His daughter's house made it and everyone is safe.

this makes me happy.

[DrPepper]

Thank you for the updates on Shirley and the engineering info.

I looked up my local standards (Buffalo, NY):
48 inch frost depth
90 miles per hour wind speed
50 pounds ground snow load


So, if I were building new, I would like to do
60 inch frost depth (to be like Bangor, ME)
180 miles per hour wind speed (to be like the Florida Keys)
85 pounds ground snow load (to be like Central City, CO)

[KUTradition]

sadly, i don’t think you’re going to have to worry about frost depth anymore

[Shirley]

Losing my house and all my possessions was bad enough, but even worse is learning 99 went all Randy in my absence.

[pdub]

Well shit.
How can we help Shirley?

[jhawks99]

That sucks. Glad you're OK.

I only went half randy.

[Shirley]

Well shit.
How can we help Shirley?

Thanks pdub, but considering what they were predicting, we were incredibly lucky. Still no power and barely any internet, but that’s nothing. Lots of debris to deal with, but that’s nothing in comparison, either. Thank you to everyone for the kind thoughts, it was a special kind of strange to wonder if my house and everything I own would still be there this morning.

Hope I never have that feeling again, but it is Florida.

[Shirley]

That sucks. Glad you're OK.

I only went half randy.

You say that like it hasn’t undermined your integrity forever.

[Sparko]

Never go full Randy.

[Shirley]

Never go full Randy.

^^^

[RainbowsandUnicorns]

Well shit.
How can we help Shirley?

Thanks pdub, but considering what they were predicting, we were incredibly lucky. Still no power and barely any internet, but that’s nothing. Lots of debris to deal with, but that’s nothing in comparison, either. Thank you to everyone for the kind thoughts, it was a special kind of strange to wonder if my house and everything I own would still be there this morning.

Hope I never have that feeling again, but it is Florida.

Glad to hear from you and that you're ok!
I admit I am a little confused. Earlier you said - "Losing my house and all my possessions was bad enough". Did that actually happen? If so, I'm really sorry!

[Overlander]

I have to admit, getting a text back from Shirley helped me relax a little.

You should never put full faith in a Japhy post alone