Replies

1. 
   BossHog | Apr 24, 2003 02:35pm | #1

   Wind load isn't just horizontal pressure - You also get uplift forces. It has to be calculated from all 4 directions, etc.

   The truss program I use has all sorts of options. First you have to pick the criteria - SBCCI, ASCE 7-93, or ASCE 7-98. Then there are things like mean roof height, miles from the coastline, usage category, exposure type, and net dead loads used for the calcs.

   And that's just the roof. Then you have to figure the rest of it all the way down to the foundation.

   So they're right - It isn't that simple.

   I went to the museum where they had all the heads and arms from the statues that are in all the other museums.

1. 
   toast953 | Apr 24, 2003 07:18pm | #2

   Boss Hog, no, I'am not an engineer, I'am not that smart either. Though I do enjoy (most of the time) dealing with the building dept. , I , sometimes don't always agree with the "rules", being's how this is an inspected project, I may have to, oh , I'll use the word, cooperate. The city is calling for a Post base anchor,"Simpson PVA" that is essentially a piece of 3/4" allthread, 15" long, 5" in concrete, 10" epoxed into round post. That is where I'am having problems, relying on epoxy in wood (pine), for uplift, ugg.But as , I think it is Mike Smith is fond of writing, but Hey whatda I know. Thanks Boss, for your time. Jim J  ps, I've always relied on gravity,  straps, nails, and throw in a little common sense, lol

1. 
   diddidit | Apr 24, 2003 07:32pm | #3

   Where are you, 44? Here in West MI, in 1998 we had two freak windstorms, the worst of which sported 130 mph gusts. Took down an apartment building - amazing there were no deaths. They called them "Derecho Winds" - something about the jet stream being briefly diverted to ground level or something like that.

   didUnencumbered by knowledge or fear...

2. 
   GoldenWreckedAngle | Apr 24, 2003 07:59pm | #4

   I've always relied on gravity,  straps, nails, and throw in a little common sense, lol

   Car ports are one of the primary projectiles that end up wrapped around stuff when we get the big winds here in Texas. There isn't enough gravity or common sense in the world to keep one of those things on the ground when a gust of wind gets under it.

   I think I understand you to be saying that you are building this car port over an existing slab? The anchor pin with epoxy sounds like one of your better options in that scenario. Whatever you do, just make sure the roof is every bit as tied down as it is held up and the inspectors will probably be ok with it.

   Course, the easiest route is to do it the way they say- then you know they will be ok with it. Whatever you decide on, it wouldn't hurt to run your solution by them before you implement it. 

   "One machine can do the work of fifty ordinary men. No machine can do the work of one extraordinary man." -Elbert Hubbard-

1. 
   toast953 | Apr 25, 2003 08:16am | #8

   diddidit, I'am in Prescott Arizona, Wrecked Angle, the slab will be poured soon. The City  is calling for the all-thread with epoxy in a pine  pole,  or equal. I agree with you , that when that "Gust of wind'' hits , even if a person has the whole Simpson Catalog  of hardware on their building , it won't  be standing, this is my own feelings/ observations. W.A.  again you are correct in the assumption of doing it the City's way, but it is not their Carport, around here, every set of blueprints the City, and or County approves, they stamp it in big red ink,, "they are not responsible for anything , nothing", I try and see the humor in that. Yes, prior to start I will run my ideals thru the City, that makes everybody more friendly, thanks Wrecked Angle,.... piffin, thanks for the heads up on the frenstration angle.... Junkhound, I like the ideal of something user friendly, thanks..... Ken, I understand what  you wrote, but for me, I like to have a good feel , for the reasons, when someone else is telling/dictating me. For when I'am spending someone else's money , I treat it as if it were my own, hard earned. I thank all you all's here @ Breaktime,,, Jim Jensen

1. 
   joeh | Apr 25, 2003 05:46pm | #9

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   Posted on Thu, Apr. 24, 2003

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   Johnson County destruction blamed on straight-line windsBy Chris VaughnStar-Telegram Staff Writer

   VENUS - For a brief, terrifying minute, Maria Tangume and Robert Carter knew their mobile home was literally blowing away.

   Until the bright light of a beautiful Thursday morning shone on their modest homestead, however, they didn't know how right they were. The roof, the front part of the house, the kitchen were all gone, blown off to some pasture down the road.

   "We worked so hard to get what we have, and we don't have anything now," Tangume said. But pointing at her husband and two children, she said, "I've got them and that's what's important. We'll just start all over."

   The Johnson County Sheriff's Department said the damage from Wednesday night's powerful storm covered about five square miles, but the storm unleashed most of its ferocity on one single street _ Sally's Way.

   Sally's Way is the heart of Sunwest Estates, a close-knit neighborhood of mostly working-class houses and mobile homes off County Road 616, about halfway between Venus and Lillian.

   Johnson County Chief Deputy Jimmy Johnson said 48 houses were destroyed or sustained heavy damage, including some along County Road 109. Countless others had minor damage, he said.

   Despite the damage, injuries were few. Two women were taken to hospitals by helicopter ambulances and one man was taken by neighbors. He was released Thursday and returned to watch a bulldozer form a pile of his house.

   Johnson said deputies, state troopers and constables would provide round-the-clock security near the most affected areas for at least another 24 to 48 hours.

   Electric crews worked throughout Thursday to restore power to the area, and for a second night, the American Red Cross opened the Venus Civic Center as a shelter.

   After surveying the damage, investigators from the National Weather Service's Fort Worth office said it most likely was caused by straight-line winds.

   That determination is based largely on looking at the way debris is scattered, said meteorologist Daniel Huckaby.

   "With downburst winds, all of the trees will be lying in the same direction, and usually the damage swath is larger," he said. "With a tornado, things look as though they were being sucked into the center of the damage path."

   Low-level tornadoes have wind speeds beginning at 40 mph. Weather service investigators estimate Wednesday's winds topped 100 mph, the equivalent of a high-end F1 tornado and sufficient to peel shingles from roofs, knock mobile homes off their foundations and blow cars off roads.

   With that kind of intensity, the distinction between twisters and strong winds is mostly only of historical interest, Huckaby said.

   "Here in Texas, the straight-line winds may not sound as exciting, but this event shows they can be just as damaging," he said.

   On either side of Jerry and Diania Blanchard, houses were completely destroyed. But for them, the storm consisted of just two blown-out windows and some water damage.

   "I was trying to watch the Mavericks game," Jerry Blanchard said, referring to the Dallas Mavericks basketball playoff game against the Portland Trail Blazers. "Then the satellite went off and then the lights went out. I thought all the noise was hail falling, so I got up to see how big it was. Then that window blew out, and I knew we were in trouble."

   After the driving rain let up a few minutes later, Blanchard grabbed a flashlight and headed outside to check on neighbors. He found one of his neighbors somewhat delirious and another _ Marilyn Earl _ trapped with broken bones.

   Earl was taken by helicopter ambulance to a Fort Worth hospital. Her family declined to be interviewed, but they said her injuries were not life-threatening.

   As American Red Cross workers moved through the neighborhood, assessing people's needs, they discovered many people who had no homeowner's or renter's insurance.

   Jerry Mathenia has lived in his mobile home on an acre of land for 18 years. He chose it because of its view of Lillian a few miles off, and because he didn't want to live near a creek that might flood.

   But this is the second time he has been through a mighty storm. Except the last time, he had insurance. This time, he has no insurance and he's without work.

   "It took me 18 years to build this place up," he said. "I don't know what I'm going to do now."

   He wandered around a bit Thursday, checking on neighbors, trying to cut a giant piece of nylon wrapped around his pickup's front axle, picking up his dead chickens, worrying about the meat in his freezer ruining.

   With his mobile home in bad shape, Mathenia didn't know where he would start or where he would go. Probably nowhere, he said.

   "I've got too many animals to take care of to leave," he said.

   Then he sat down on the tailgate of his pickup, alone.

   For people who are uninsured, the Red Cross can help with clothes, food, mattresses, pots and pans and other "things that people need to put their house back in order," said Anita Foster, a spokeswoman for the Chisholm Trail chapter of the Red Cross.

   Lisa Goodwin had stayed at a friend's house Wednesday night, unaware that the storm had tossed around her mobile home and wrecked most of the antiques her mother had left her.

   She saw the news Thursday morning and thought she recognized a neighbor's house. Then a friend's phone call confirmed it. She drove up to where she lived and could think only one thing _ "I'm glad I wasn't here."

   A few feet from the rubble of Tom and Kathy Schutte's four-bedroom, doublewide, their family gathered in a circle to pray before eating the white-bread sandwiches brought by relief workers.

   The Schutte family missed the utter destruction of their home because they were at Venus High School, watching their daughter perform in a play.

   They missed their mobile home rolling over and over and over until it stopped 200 feet or more away, the contents forming a pile no higher than two feet.

   And they were about to miss Tom Schutte's job. His long-haul trucking company told him he had to get back on the road in two days. He told them to come get his truck then; he wouldn't do it.

   "Lord, watch over all the families that lost everything here," one of Kathy Schutte's brothers prayed, his voice breaking amid the sound of sniffles. "All this stuff can be replaced, Lord. But the bodies can't."

2. 
   toast953 | Apr 27, 2003 08:11am | #10

   JoeH, thanks for an interesting article, I feel for the people, but , as they mentioned they are alive, thank goodness. I   would be curious as to what type of  "Holddowns" were used, for with Mobil Homes, I would think that would be an absolute item to address, along with anything else that may go flying off, rolling, sailing, with the potential to harm people. thanks again Jim J

3. 
   joeh | Apr 27, 2003 08:31am | #11

   Jim, I don't think there's any way short of a net to anchor one of those things.

   I bought a 30 travel trailer for construction site housing.  There is a large steel frame, but the trailer itself is built of the cheapest, thinest, cheesiest crap you can imagine assembled with probably 2 million narrow crown staples.

   No way it would survive a tornado no matter how well the frame was secured to the planet.

   Joe H

4. 
   toast953 | Apr 27, 2003 09:31am | #12

   JoeH, my own thoughts, yes, when Mom Nature strikes, well, depending on the mood she is in, will dictate to us, what she has left. As a rule, the inspection process is good, I also believe in common sense, and gravity. If the Big wind does strike a structure, as far as I'am concerned, it's doomed. I don't mind building for the "little winds" , for I know I'am going to lose building for the Big One. Again, just my own thoughts/feelings. Jim J

2. 
   Piffin | Apr 25, 2003 01:59am | #5

   Your window manufactureer has charts showing which windows fit that criteria. As a basic rule of thumb, if they are approved for Dade county, they are approved for anywhere.

   But the whole wall is part of the calculations too. The manufacturesres rep needs to be involved in a whole window wall design layout so there is no simple answer to your question unless it is just one window.

   .

   Excellence is its own reward!

3. 
   junkhound | Apr 25, 2003 06:18am | #6

   go to a nearby federal bookstore (or on the web) and order a classic copy of "The effects of nuclear weapons".  There is a neat little circular slide rule still in the back cover that converts wind speed to overpressure and time duration, also to MT blast and distance to center <G>

1. 
   KenRubin | Apr 25, 2003 06:45am | #7

   The new (2002) building codes for residential housing is "The Book".... YOu do not have to agree and the code does not have to make sense to everyone... But it IS the code.... The simpson strong ties in corners is a real pain to intall correctly... But it IS the code...... The new wind code is particularly interesting and the wind map may be confusing... But it IS the code.... Even the new window / wind speed chart is cute.... The one that confuses me is that there is not one for a garage door specifically !!

   Ken in Savannah