Hurricanes and earthquakes and fasteners
Up here, five hours north of New York’s Long Island, we get a few powerful noreasters each year, and every few years, we may get the tail of one of the big hurricanes. Very occasionally it is more than just a tail. The forests around our Adirondack high peaks region are spotted with some large tree-blowdown areas, that date back to hurricane seasons from generations ago.
We happen to be in an earthquake zone, one labeled severity D1. One occurred almost ten years ago, and I recall how it felt and sounded. The house was shaking violently, and the large trees visible outside were shaking and swaying. The number was about a 5.5, and the noise sounded like a freight train coming though the house. Apparently our quakes are noisy because of the type of bedrock we have.
I have been reading codes and prescriptive engineering for doing some plans I have been finishing, and here is what is going on the sheets.
Foundations require additional ties between footings and walls, and so the hooked dowels set in footings that extend up into the walls, are specified as #5 bars spaced at 18 inches.
Nothing more is required in the way of rebar in the walls, other than that needed for other structural considerations, but at the tops of walls, the callout for anchor bolts now reads one each 18 inches, minimum 7 inches embedment, minimum 3/8″ diameter.
To tie the deck platform to the foundation walls at over-the-top joist bearings, I am calling out the use of one Simpson A3 18 gage angle clip, to help fasten each joist or floor truss to the mudsills upon which they bear. Fastening is a total of 8 nails, 10d x 1 1/2, 4 into the joist, and the others into the mudsill.
I’ve not seen the need to specify ties across floorframe rims where second floor platforms and walls sit atop first floor walls, but up at the plates upon which roof rafters or trusses bear, I am specifying the use of two Simpson H3 hurricane clips for each rafter or truss bearing.
We don’t have plans review in our small-town building jurisdictions, inspections are few and spotty, and whether or not the precepts I detail out with plotter ink on paper are followed, I don’t know. But my name is on those sheets, and I feel OK about it.
Edited 5/30/2009 10:48 am ET by Gene_Davis
Replies
Was there a question in there somewhere?
k
No more a q than in one of the "how I built this" posts with all the photos.
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"A stripe is just as real as a dadgummed flower."
Gene Davis 1920-1985
Not trying to one-up you, but you say you had a 5.5, and it was impressive.
Imagine a 7- like Loma Prieta, that's fifty times as strong. Whoa.
And the Hayward fault is due for a 7-8. Yikes.
k
We are installing about 350 Simpson SHTT14 holddowns at the project we are building.
And that is only on the ROOF! Mike
Small wheel turn by the fire and rod, big wheel turn by the grace of god.
While the hurricane-prone regions include a whole lot of acreage, so also do the parts of the map zoned seismic D1 and shakier.
That includes the region of the New Madrid fault, which begins in south-central IL, and tracks the general vicinity of the Mississippi valley down as far as central AR. That is a pretty big region, and it contains the big metro areas of St. Louis and Memphis.
There is a pretty large part of eastern TN zoned D1 and stronger seismic, and this one surprised me, most of tidewater SC is an earthquake zone, with things getting really strong around what looks like Charleston.
And then there is the west coast, of course.
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"A stripe is just as real as a dadgummed flower."
Gene Davis 1920-1985
That's right, I remember you said your company was getting into the seismic game. Is this a retrofit, or new work? Are you playing with Simpson-Ties too, or are you strictly a rock man?
Were you in Alameda on October 17, 1989? Or maybe at Candlestick?
k
I was living in the Mission in '89. I was riding my bicycle to Candlestick that day, I took the quake as a good omen. Did not realize the seriousness of it all 'til I was in my seat at the park. Crazy part was I had driven home from Alameda that day, through the colapsed Nimitz and acroos the Bay bridge.
Doing Pittsburg High right now. I hate the term fast track, but this job is extremely that. Framing a pretty cool Mansard roof, about 2500 lineal ft of it. I'm gonna post some pics eventually.
How 'bout yourself, where were you? Mike
Small wheel turn by the fire and rod, big wheel turn by the grace of god.
Wow. You came through the danger zone unscathed.
I was in a corner store (buying beer for watching the game, natch) on Ocean Ave, near City College in S.F.
I was taking a five dollar bill in change from the clerk as the rumbling started. He had this round Yemeni face, and his eyes got bigger and bigger as we realized it wasn't a muni car (I'm sure my face was doing the same thing...)
The bottles started clinking and clanking and crashing, and I saw all the glass all around me, including the plate glass window, and bolted out front onto the curb, trying to stay away from all the store windows..
The overhead muni lines were starting to jump around pretty good, so I was kind of in no-man's land, glass to my left, and wires above to my right.
I could see a long stretch down Ocean Avenue, so I could see the shock waves rippling up the avenue towards me. I had to kind of flap my arms to stay on my feet. Surfing a sidewalk is a trip, let me tell you.
I remember the progression of awareness- "hey, rumbling. hey, earthquake. hey, kinda big earthquake, get the f outside! holy ####! really big earthquake! Whoa! this has got to stop! this has got to stop! oh s**t, it's not stopping!"
My mind finally got to that point, where it just kind of stopped forming judgements about whether what was happening was ok or not. Like, whether I knew if the ground was solid or liquid, didn't really matter to fate. Can't let go and you can't hold on. I bet you can relate. ;)
I haven't been the same, ever since. Seriously.
I can't imagine what it was like in Santa Cruz...
Once it settled out, I grabbed my beer and scooted back to the house, where my friends were prepping food for the bbq. On the way home, I saw some broken glass, a couple of chimneys down, and a lot of cracked stucco, but no major damage. Pretty amazing, really. We had a big earthquake party in the backyard- it wasn't till later we heard about the Cypress Structure and the bridge.
k
As I remember that night, most people stayed outside. We sat in our car parked on Bernal Heights and watched the Marina burn.
We were supposed to get married in City Hall the next week. Ended up giving my series tickets away and got married in Jamaica. Moved to the East bay in '90.
I've got our house bolted and sheared pretty good but Alameda has got that liquification factor similar to the Marina. Pretty much all sand here.
If the thunder don't get you... Mike
Small wheel turn by the fire and rod, big wheel turn by the grace of god.
Sounds good to me. It couldn't hurt and if you do get the big one it will pay off.
I grew up in L.A. and went throught the northridge earthquake as a home owner.
Unbelievable amount of force put on a house. A fair amount of relitavely new homes jumped off thier fundations.
Opps! Back to the drawing board.
Will Rogers
Have you seen the propaganda for Hurriquake nails by Bostitch?
I emailed them asking where the nails were made and if the manufacturer was fabricating them to ISO 9001. Their reply was China and they attached links to several sites which tested the nails. I consider their reply skirting the question of quality of manufacture. Sure, they can reference test reports but if they can't assure the quality of manufacture, those reports are just nonsense. The nails used by those reports could have had excellent pedigree and therefore could withstand the testing. However, if the mass production was c**p, then the actual use and field installation would not measure up to the report's findings.
At first, upon reading the propaganda, I thought this must be better than sliced bread. Like most Chinese made products, the actual v. perceived performance will leave much to be desired. Unfortunately, HOs won't know until their roofs blow off during the next hurricane.
That's why I get all my gun nails from the village blacksmith, with handwoven organic hemp stripping.
k
How much for 10,000? :)
Now you've got me wondering- are there any collated gun nails that aren't made in China?
k
I guess the only to find out is to email the manufacturer. Bostitch in their reply said that they did have some nails made in the USA. I had to specifically ask them.
I was working on a Navy base years ago and someone insisted our drywall screws be made in the US. Grabber came out and with a few empty boxes with "made in USA" printed on them and we transfered the screws. Mike
Small wheel turn by the fire and rod, big wheel turn by the grace of god.
In the 70's I worked on a military housing project and the Corps of Engineers insisted that the TV coax transformers be made in USA. The electrician told them that those items were no longer manufactured in the US. Either they accept the ones installed or they will give the govt credit for the items and not install the items. The govt relented. In the intervening years, it went from the 300/75 ohm transformer to TVs are no longer made in the USA.
In another thread, I agree it is nearly impossible to buy American made products for certain items. Even food, many items come from southern countries during the "off season." NAFTA was the door that opened the flood gate.
Maze Nails?<http://www.mazenails.com/companies_maze.php>The ToolBear
"You can't save the Earth unless you are willing to make other people sacrifice." Dogbert
Gene Davis,
Fine home building did you a great favor with their Framing Roofs book. they showed the relaTIVE STRENGTH OF EACH FASTNER TYPE MADE (OOPS) go to page 126 and there is independant testing done of the strength of each type of fastner (the chart is on Page 129)
The strongest connection they Tested? A simple 3/8ths inch lag bolt improperly installed. 2783# (but installed the way most carpenters would)..
The Simpson H7 is only 57 pounds weaker. Your simpson H3's will fail at 1002# compared to properly toenailed rafters which will fail at 208# that included time to predrill holes for the 16p nails they used which split the wood otherwise..
So your H3's will give you about 4 times what ordinary nailing will but for maximum protection you could go with either Lag bolts or Simpson H7's