Shear Walls for Typical Long Skinny City Lot Building

[Greatone76]

I feel like I'm missing something. All the time I am handed architectural drawings with city lot (not much width) open concepts plans and I look at the huge windows in the front facade and the double patio door at the rear and nothing for walls in the middle and wonder where the shear walls or other lateral systems are.

When you have a 20-foot wide building that is 60 to 80 feet long and 3 levels high (first second and attic at a minimum), how in the world are people getting an open concept to work at the first level. I feel like I tell a least one person every other week that I don't understand the basics of their plan, so I can't assist with the project because it doesn't have an adequate shear wall system.

I have designed shear walls for these type buildings and need 10 feet or more of length at 3 locations to even get a heavy wood shear wall to have a chance?

What am I missing? How are people getting these low width plans through review with nothing labeled as a shear wall and no substantial walls at the first level?

 

[JAE]

Moment Frames?

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[msquared48]

Or Simpson Strong Walls - expensive, but already rated.

Mike McCann, PE, SE (WA)

 

[Greatone76]

There is typically no steel called out on the plan, let alone detailed as a moment frame.

Again nothing called out as a shear wall on the plans, so no use of a "Simpson Strong Wall".

I think it is architects in our area using the title of "Interior Remodel" to neglect the overall lateral because they aren't "Substantially Changing the Exterior Walls"

I don't care what it is, I don't see how any reasonable municipality is accepting a set of the plan without anything labeled as a shear wall when there is an open floor plan on a 20-foot wide house. Even as a solid front and rear shear wall with no openings a "typical wall" don't work for shear at a certain length. It at least needs to be detailed with special details because the "standard residential attachements" aren't acceptable.

What kills me if I go to existing residence where people have removed a bunch of the interior walls to make them open floor plans and have added the correct beams, but the whole house is leaning because the front wall has too many openings to be a shear wall and the next 2 parallel to the front walls were removed to make it open, so the first shear wall is 30 to 40 feet back into the house.

 

[msquared48]

I hear what you are saying and have run into the situation before too.

You could always write a letter to the local jurisdiction as a concerned structural engineer to do your due diligence, but will probably not get anywhere unless you walk in with a consortium behind you...

Just a thought.

Mike McCann, PE, SE (WA)

 

[KootK]

Yeah, my region is terrible for this. And, oddly, our new energy code seems to be making it worse. Somehow, it's now a code mandate for these kinds of building to have no lateral system on the front wall. And, in my area, taking a hard line on moment frames or the Simpson toys will get you dropped in favor of another engineer in a heartbeat. It's not done good things for the health of our structural engineering marketplace. Local code officials are willing to trust anything with a stamp on it which is nice when it's working in your favor but unhelpful when it's steering local practice towards the eventual pancaking of entire row-house complex. That'll happen eventually, I feel it in my bones. P-delta failure of a two or three story building. What a sad day for structural engineering that'll be.

 

[pmtrevisan1]

koot.
same here in Ottawa

I have had numerous conversations with our chief bldg official and all I get is all we need is a stamp.

this removes liability from the city but does nothing for our profession.

I have the same feeling as you, when we do get a design event quite a number of projects will come down. then the officials will stand up and mandate better laws regulations etc. pity that they are always reactive as opposed to proactive.

lost count how many projects I've lost because I stood firm that the bldg needed lateral analysis and restraint. yet another engineer gets the project and no lateral system in place..

 

[merrittEIT]

Following this thread to gain some insight. I've always wondered about this. I spent 3.5 years in Tennessee designing floor and roof systems for reno and new construction. Most of the new construction within Nashville city limits are "tall skinnies". Three stories with an open concept on the first floor and large picture windows at the front and back of the house. Cities are doing this to get as many properties as they can on a plot of land to provide housing.

I always engineered these systems with a Simpson Strong tie package for stability. Whether the GC bought that package or not is another story. A lot of times I would go to job sites and find the hurricane ties and joist hangers laying in a box and the frame toe-nailed together. It seems code officials are only reviewing load paths and beam calculations and that is only in some area codes while neglecting connection details etc. In Tennessee structural stamps are not required for residential building.

 

[HouseBoy]

I've run into the same dilemma and wonder: How do they do (get away with) that?

Here's one (picture attached) I came across recently. Continuous LVL "studs" placed periodically in the walls.

I've also seen "moment frames" made with 4" steel columns and shear plate connections for the beams.

Makes it hard to sell the correct solution some times.
Just gotta keep with the clients who appreciate what you bring to the table.

Steve

 

[OldBldgGuy]

Moment frames. I had a craft brewery going into a heritage building in downtown Niagara-on-the-Lake, 19' wide, 85' deep once the addition on the rear was done; the existing front wall had to stay but not much else because it was zero lot line and the neighbours are 40' deep. Architect wanted all glass, open concept looking through the bowling alley of retail/tasting/brewing/shipping-receiving. It's there, 4 years old, and very successful. Incidentally, half of the existing and all of the addition has a 20' deep basement under it where the brewery tanks are, which was another story, and something the owners and I were told couldn't be done. National historic site next door with a 7' deep stone basement on the zero lot line and no disturbing it was allowed. I've worked on the NHS both previously and post this project, and both the brewery owners and the heritage site are still talking to me.