Resisting Uplift 1

[wcand]

Due to the lack of buildable lots in our area many of our clients are coming in with odd design shapes. For example a home 64X20. This leaves us no choice but to have some interior shear walls in the middle of these homes. It is not uncommom for uplift to be around 9 or 10 kps sometimes higher. Contractors have problems when we run foundations through the center of the house as it hampers access and if you were to design so that you had enough concrete to react 9kps, well use your own imagination at 150 psf. Does anyone have any creative solutions assuming we have no other walls to distribute shear forces to?
Code: 97 UBC

 

[Taro]

Here's a few options I have used:

1. Continuous footings that tie into and engage other adjacent foundations.

2. Uplift anchors. Similar to tiebacks in retaining wall construction, but installed vertically. Helical piles seem to work well.

3. Count on more tributary area for uplift than for downward loading. In order for the wall or frame to overturn, it has to take the adjacent framing with it.

 

[AlohaBob]

We designed storefront homes in the market district in San Francisco. Parking and real estate is a premium. So the structures are 3-4 stories tall and include soft stories at ground level. Although they are light frame construction, we used steel moment frames to handle the loads.

 

[boo1]

Have you considered a tie rod system? We use the Tie Max system for high uplift cases.

 

[AlohaBob]

Rather than add weight to the foundation, I would look to mobilizing the structures own weight to resist the uplift too.

I've used a concrete tie beam across the foundation. Maybe this can work multiple ways in the structural system.

 

[boo1]

Of course you need the mass in the foundation to resist overturn and the axial loading. But, the post asks about shear wall and high up lift points.