PRACTICAL guide to beefing up seismic resistance in new construction?
I am designing my new place and although I am required to have the structural design sealed by a p.eng (SE) I am sure my SE’s expertice lies in “code-minimum” designs for sub divisions. This is fine since our local code is relatively “seismic aware” however as it will be my house and I am acting as GC & framer I want to go beyond “code-minimum”.
What I am looking for is advice, details or a book etc that provides basic framing upgrades that give good “bang for the buck”. (Think what $0.50 huricane clips have done for those in high wind locations.) Has anyone seen any details like this? I realize this sounds like a very broad request but I have not been able to locate anything other than books dealing with the computational engineering aspect.
I CAN find lots of good info on seismic upgrading of existing homes, including a nice drawing showing the appropriate application of Simpson products, but nothing on new construction. (Perhaps there are liability concerns.)
As it stands I have a reinforced monopour concrete footing and foundation with 5/8″ SSTB16 anchor bolts @ 48″. Solid lumber framing with 100% 1/2″ plywood sheathing. Sheathing laps rim joist by 2″ and edge nailing applied to rim joist as well as closer nail spacing in field. Corner anchor bolts extended with 5/8″ threaded rod to attic framing with 3″ square plate washers. Although the foot print is only 36″ square the interior is bisected by bracewalls with 1/2″ plywood sheathing on one side. Sub floor and roof sheathing glued and nailed. Window openings kept fairly narrow (max. 36″) with multiple units used to effect more glazing. Single car garage door with site built box beam side columns and built up header. Not sure what else I should describe here but you get the idea.
Thanks
John
Replies
The prescribed sesmic methods detailed in the IRC show good residential sesmic methods.
Happily, the Supreme Court ruled a few yeas ago that if municipalities were going to incorporate published codes into law, the code was public domain.
Here is the IRC - big files, someone else may search then for you, I wont. <G> http://publicecodes.citation.com/icod/irc/2009/index.htm
Thank you for sharing that link. I've tried to find the IRC before and all I got was ads to purchase an expensive printed copy. This will be helpful.
Have been trying to find a pdf file on-line, would be easier to print out the section one wanted.
The other way is to go to the library ref section with lyour digital camera and take a pic of the pages of interest. I've done that for the full service manual for every vehicle I have. Heck, $700 a year to library in taxes, I oughta get something for it, eh?
Single story or multi story?
Requirements for a single story are much lower than for a multi story dwelling.
Without doing anything else, boosting the number of fasteners in the shear panels will boost the strength of each panel.
Normally the base is every 6" around the edge, 12" in the field... you can just make it 3" and 6"... all it costs is more nails and a little more time.
Bostitch makes the "Huriquake" nail, special designed for wind/ shear loads.
fastener schedule could be doubled
Yes, thank you for pointing that out and i have also looking into the huriquake nails although doubling the number of nail likely makes a bigger impact.
Also, thank you for the IRC link but after a while of looking around in there i didnt find anything like a detail or checklist of items to consider such as increasing the number of nails.
John
I vaguely recall someone else was doing some quake upgrades a year or two back. He was apparently working from some sort of list and improving the house-foundation fastening was a major item on his list. Apparently a lot of failures occur when the house simply shakes off its foundation.
For retrofit there is a ton of useful info out there. Its the new construction that they are tight lipped about.
This ain't right?
Single car garage door with site built box beam side columns and built up header.
What are you thinking?
Joe H
Could be right
Our code doesn't have much to say about single garage door openings. There is only a shallow roof over it, no second floor or anything like that. If our code allows me to just use regular studs and exterior 1/2" sheathing surely added 1/2" to the inside of these narrow walls would be a significant INCREASE in seismic resistivity. After all that's essentially what some of the premanufactured panels are.
A built up beam seems perfectly acceptable as well. The span is only 9' and if the aforementioned panels are tied into the beam the whole will act more like a moment frame than 99% of the garages currently being built around here.
Anyway sorry if that sounds like a rant but from my perspective this is quite reasonable.
John
I was thinking why build a tiny garage?
But as tyo the how of it, someone makes some garage opening units that are engineerws steel and ply (I think)
Been awhile but I saw them at a JLC show years back.
Joe H
Design for a higher siesmic zone.
Have the Engineer design for a higher siesmic zone.