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Conservative engineering.

Discussion in 'Residential Foundation Codes' started by ICE, Jul 30, 2011.

  1. ICE

    ICE Sawhorse

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    At the footing inspection, I noticed that there were two SSTB at this corner. The plan showed both HDs and different sizes. I explained that only the 8A made sense and they should call the engineer and ask her if she really meant for there to be two on the same post. Upon re-inspection for corrections, they were still there and they said that the engineer was adamant that there be two. I said OK but you cant put them both at the bottom and explained the use of a coupler nut and all-thread. They went back to the engineer and she took it a step further by adding the 4x.

    [​IMG]
     
    #1 ICE, Jul 30, 2011
    Last edited by a moderator: Jul 30, 2011
  2. Daddy-0-

    Daddy-0- Moderator

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    Even the engineers don't understand braced walls.
     
  3. TimNY

    TimNY Platinum Member

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    Probably using one HD to resist shear/overturn in one direction, and the other to resist same in a perpendicular direction? What seismic/wind zones are you in?

    I've never seen it like that.. But I've never seen bolts used either.. I usually see Simpson screws.
     
  4. Mark K

    Mark K Platinum Member

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    The 4x filler is confusing. It almost seems as if somebody believes that the holdown must sit on wood.

    There are some holdowns Simpson says can be placed directly on the wood but it is always acceptable for there to be a gap. The concern is that if there is a gap the nut on the AB can be tightened so that when uplift occurs there is no slip before the HD starts to carry load. This reduces the deflection of the wall and hence the damage. This is much less of a concern when screws are used to attach the HD to the post.
     
  5. MtnArch

    MtnArch Sawhorse

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    But the numbers say this is right ....

    ;-)
     
  6. ICE

    ICE Sawhorse

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    We are zone D with 100mph wind. I've always thought a hold down in a corner worked in both directions.
     
  7. Rio

    Rio Silver Member

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    I think they only work in one direction. On the bolts vs. the SDS screws, I went to a seminar at the Simpson plant in Brea and they said the problem with bolts is that it's hard to line up the hole oftentimes so the installer will over drill it and then when there's a seismic event there will be too much play and the assembly will fail at the bolt hole, splitting the wood. The screws don't have that problem, are easier to install, and also have higher values usually.
     
  8. TimNY

    TimNY Platinum Member

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    I have seen it engineered with only one. I don't know if it is correct or not.

    I suspect that for some reason 1 holddown did not provide adequate strength (the one on the right seems pretty small). ALthough in a 100mph wind zone I suspect they are usually that size.

    Who knows. Nice job either way :)
     
  9. ICE

    ICE Sawhorse

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    The structural engineer at work tells me that one is all that is required in a corner.
     
  10. Daddy-0-

    Daddy-0- Moderator

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    One anchor is usually sufficient in a corner if it is framed correctly. The plywood and corner studs will transfer the racking resistance. The oversized anchor just keeps the whole assembly from pulling off of the foundation.
     

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