Residential Remodel Theory, Wood Shear Walls, Existing Let-In Bracing

[somedude2]

I am a newly licensed engineer. I am staring to get a few jobs most of which are residential remodels.

Question:

Are there any books or reference materials that people can recommend in regards to the approach of these small type projects. I realize to be on the safe side, most engineers assume any change leads to a complete lateral analysis and retrofit of walls /underpinning existing foundations. I think this is overkill in most situations, especially when the remodel is minor.

How do other engineers account for existing walls/lateral systems? What vaules can be assigned to existing walls with let in bracing?

How do you work these projects to cover your ass, but at the same time, provide solutions that are economical and not over engineered?

As an aside, I realize now that I have been working and out of school for years now, that textbooks are not the best resource for practice...I think it has to do with the liability of providing any detail or idea that could be applied in practice.

Thanks for your comments.

 

[BAretired]

You might get some help from this Webinar:

http://www.asce.org/Content.aspx?id=12884906318

BA

 

[MiketheEngineer]

Let in bracing is covered in the IBC or at least it was last time I looked.

Sort of answered this same question in another post today with Google "Single story residential design for Dummies"

You will get a bunch of hits - to my amazement!!

Read the IRC and IBC - it will help a lot.

Then there are a thousand books out there that cover portions of what you are looking for...

 

[a2mfk]

Residential remodels can be very tricky because they are all so different. Budget in a couple of site visits and put CYA notes on your plans that allow you to make changes after demo, field verify and notify engineer, etc... Give yourself a second chance once they uncover the structure.

I am in Florida so I am very careful with wind loading. One story houses usually are fine in lateral capacity if you don't tweak them too much from their original design, but you have to run some numbers and sometimes add some shear wall or simply tell a client they cannot do that and be prepared for the push-back. I always am conservative with uplift and lateral loading on walls and roofs that we have touched, once your name is on a drawing they will come to you if there are problems down the road. Especially true if its an older house, you are likely the last and maybe only professional who worked on that structure.

Bottom line- maintain the load path from top to bottom, and don't just punch holes in walls without making sure you are good in shear... A lot of what I see built in residential construction in the last 10 years I doubt would check out 100% if someone ran a true structural analysis.

Besides that, and more specifically, Meyer's timber design book and the American Wood Council's specs are great, a good CMU design book is probably in order if you don't have one, and get used to Simpson connections and the like because they will be part of your life.

 

[JoshPlumSE]

To me it is a simple issue of load path....

If you are removing a bearing wall and replacing it with a beam and post, then you need only design the vertical system. It still must be tied into the lateral force resisting system, of course. But, if you aren't changing the lateral loads, then you don't need to worry about re-analyzing it.

The same thing goes in reverse. If you are removing a portion of the lateral force resisting system, then you must re-analyze that system. But, you can ignore the portions of the gravity system which are not directly supported by the elements you are removing or changing.

That being said, I've worked on projects where you realize that there really isn't much of a lateral force resisting system at all. Even though I was just desiging an interior beam-post gravity system, I didn't feel comfortable with the design unless I provided some upgrade to ensure a proper load path for the lateral loads.

 

[JAE]

somedude2,
If you are using the IBC or IRC, there are provisions in there for braced wall lines that do not require an actual load path calculation but are empirical code provisions that ensure a system of lateral force resisting walls.

Check out IBC Section 2308 for example. This is the IBC's version of the IRC provisions for certain, small, regular buildings that are in lower wind load areas.

If you are in a higher wind area, an engineering design is probably required per the comments above.