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Kal
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Posted: Sun Oct 29th, 2006 07:05 am |
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You mention Harlen-RFP and shear transfer ties in various places. Where can such hardware be purchased? It seems the most commonly available parts are Simpson or USP (at Orchard Supply).
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Howard
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Posted: Sun Oct 29th, 2006 03:34 pm |
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Kal, sorry. Harlen went out of business a few years ago and I just haven't had time to update the website. KC Metals in Sunnyvale California makes MSPs but the RFP and 256A are no longer available along with a large number of other fabulous retrofit products. Once a big earthquake hits similar products will be available again.
Howard
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jbArch
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Posted: Tue Nov 7th, 2006 12:41 am |
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So what are you using in lieu of the Harlen-RFP?
At this link:
http://www.bayarearetrofit.com/RetrofitDesign/Bolting/bolting.html#homes.with.low.clearance
... the RFP is mentioned as an alternative to Simpson FJA. Looking at Simpson's catalog I would have thought the FAP or HFA-series was a better choice (assuming you are limited to Simpson products).
What do you all think of the Simpson UFP series?
Cheers,
JB
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Kal
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Posted: Tue Nov 7th, 2006 02:52 am |
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Maybe this is getting off the subject, but if Harlen parts are no longer available, what is the average homeowner who wants to attempt a retrofit to do? Is there realistically any alternatives to the Simpson Strongtie products that are readily available via retail? Or do we just do the best we can with the Simpson products and alter the implementation to make up for the shortcomings?
As for the Simpson FJA, the load schedule would suggest that it only be considered for preventing vertical (uplift) motion and you'll need to use something else for the lateral (shear) motion. But then, there are only so many holes you want to drill in your foundation.
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Howard
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Posted: Tue Nov 7th, 2006 03:30 am |
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Kal,
It does not matter who makes the products. KC Metals and USP also make good hardware. KC Metals is the only one that still makes the old Harlen MSP. Harlen had a few products that Simpson does not make but Simpson stuff works fine. You just need to make sure you are reading the catalog correctly when doing your designs. The engineering tables for all manufacturers read the same.
DO NOT use the FJA. The uplift motion you are talking about is not an observed cause of damage in buildings unless it is caused by overturning or uplift on the ends of shear walls. FJAs do not resist this type of force in shear walls, only in joist to concrete connections where uplift is not a concern. If you look at their lateral resistance under the F1 column in the catalog it is only 185 pounds so you would need about 7 of them just to equal a five eights bolt. We NEVER use FJAs, from my point of view they are a scam and prey on consumer ignorance.
Howard
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Howard
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Posted: Mon Nov 13th, 2006 02:18 am |
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JB,
The only product we ever use is the Simpson UFP10. The other products such as the Simpson FA and HFA provide less protection at higher cost. I don't know why Simpson even sells them anymore. NEVER use the FJA to bolt a house. They only provide 185 pounds of earthquake resistance versus the 1340 pounds provided by the UFP10.
Sorry I did not respond ealier. Somehow I missed your post.
Howard
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Steve Gemmell
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Posted: Tue Oct 27th, 2009 04:11 am |
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My engineer has make a good argument about the Simpson FJA preventing the friction plane between the sill/joist system and the foundation increasing the lateral strength of using the FJA. If you can't break the friction plane, where is the house going to go?
I would really appreciate some feed back here!
Many Thanks,
Steve
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Jeff
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Posted: Sat Oct 31st, 2009 04:04 am |
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Steve,
The FJA has a strong uplift resistance, but very little lateral resistance. So I interpreted your question as, "Can an FJA be used to increase lateral strength of the floor to foundation?" The FJA plays a roll in resisting any uplift forces, but the load path should be completed with shear transfer ties and foundation anchors. Remember that the pushing force is resisted parallel to the direction it travels, an FJA would just bend over without sufficient other hardware in place to resist the lateral forces.
Since you have an engineer that introduced the idea of a 'friction plane', I forwarded your question to our primary consulting engineer who wrote the only book available on shearwalls (http://www.shearwalls.com)
His response;
Friction is a very unreliable force in that you have very little idea how much friction you will have; that is why few engineers give friction any credit as far as resisting any loads. To get a serious friction force you would need to clamp the framing to the foundation--this cannot be done with "FJA" anchors. While the FJA anchors would generate some clamping force once the house has moved a bit (causing the FJAs to lean slightly and tighten the system up), by the time this happens the inertia of the moving house could easily overpower the frictional force and rip out the FJAs. It would probably not hurt to install the FJAs--I would just not suggest that you rely on them to counteract anything besides uplift. I would never recommend them in place of foundation sill anchors or shear transfer ties.
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