Stepped Foundations and Shearwalls
Stepped Foundations and Shearwalls
(OP)
I'm looking at this residence right now and I have two questions or problems:
1.) The SDPWS (2012) has restrictions on perforated shearwalls such that the top and bottom plate are uniform (4.3.5.3, Item 6). To my knowledge no such limitation exist for segmented shearwalls. Can a segmented shearwall have steps in it (ie. one end is taller than the other and the bottom plate is discontinuous but the top plate is continuous)?
2.) On the east elevation in the picture below you can see that I have two stories with a daylight basement on the right side of the residence. Essentially three stories. I've got a couple shearwall segments drawn in but how to get much else out of this wall is causing me to scratch my head. Any thoughts on the best way to get more shear panels on this wall?
1.) The SDPWS (2012) has restrictions on perforated shearwalls such that the top and bottom plate are uniform (4.3.5.3, Item 6). To my knowledge no such limitation exist for segmented shearwalls. Can a segmented shearwall have steps in it (ie. one end is taller than the other and the bottom plate is discontinuous but the top plate is continuous)?
2.) On the east elevation in the picture below you can see that I have two stories with a daylight basement on the right side of the residence. Essentially three stories. I've got a couple shearwall segments drawn in but how to get much else out of this wall is causing me to scratch my head. Any thoughts on the best way to get more shear panels on this wall?
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com






RE: Stepped Foundations and Shearwalls
2) could you collect your shear load at the main floor level and drag it back to the garage slab on grade rather than taking it down to the basement level foundation?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Stepped Foundations and Shearwalls
Mike Halloran
Pembroke Pines, FL, USA
RE: Stepped Foundations and Shearwalls
It's not apparent from the south elevation but the garage wall is 4 ft out of plane from the main residence wall.
I'm more worried about the East Elevation wall, he's got so many windows on the right side of this wall its hard to make anything work, but maybe I'm just not seeing it. I've never yet had to put a shearwall chord above a window header or beam, I suppose it could work but then you've got a point load on the header both in tension and compression and there will be more strapping and sizing to account for this, it just seems messy.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Stepped Foundations and Shearwalls
RE: Stepped Foundations and Shearwalls
RE: Stepped Foundations and Shearwalls
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Stepped Foundations and Shearwalls
RE: Stepped Foundations and Shearwalls
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Stepped Foundations and Shearwalls
RE: Stepped Foundations and Shearwalls
RE: Stepped Foundations and Shearwalls
If that's your competitive edge with this client then we'll have to dig a little deeper. See the sketches below. With some minor adjustment to the window locations, you should be able to slip in posts to take your chord forces to ground.
Expanding the concrete a bit on the south elevation makes sense to me. Another option to improve matters is to use a steel strap of some kind as your collector at the main floor level.
This complicates matters but is not necessarily a deal breaker. You may be able to transfer the shear down to the main floor level and then across the main floor diaphragm laterally to get the load over to where it might transfer to the garage floor system.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Stepped Foundations and Shearwalls
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Stepped Foundations and Shearwalls
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Stepped Foundations and Shearwalls
The south elevation I did not redraw since I will go with what you have drawn above (KootK), I think that is probably as good as it gets.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Stepped Foundations and Shearwalls
I would argue that, in all of the ways that matter, the perforated shear wall is done being a shear wall once it hits that main floor drag strut. After all, theoretically, there would be no shear required in the panels below the main floor. As such, I'd be willing to leave that one basement floor window alone.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Stepped Foundations and Shearwalls
A really rough mockup in SketchUp is here for those interested:
https://3dwarehouse.sketchup.com/model.html?id=b22...
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Stepped Foundations and Shearwalls