Connection between adjacent structures

[tmoesabi]

Due to a special condition imposed by the local coastal commission, a current garage design I am working on "requires that the foundation... shall be designed to facilitate moving the structure in the future if necessary."
As such, the garage is being place directly against one corner of the existing residence but the two structures will NOT share a common wall as the garage may be relocated someday.
Obviously there would be issues seismically between two such structures so my question is if anyone knows of any resources, code, or tried-and-true methods of connection between two such adjacent buildings to ensure that the resulting structures moves like a single unit (or as close as possible)

thanks a lot.

 

[paddingtongreen]

You want to have your cake and eat it too! To behave as one, they must be connected. If they are not connected, they may respond differently to the same earthquake.

An insoluble problem ceases to be a problem.

Do they really mean, "move the building and foundations"?

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[BAretired]

Could you tie the structures together using fasteners which could be removed in the event one structure had to be moved?

BA

 

[msquared48]

Why make the garage moveable not the house? Is the house grandfathered in?

I assume the foundation does not need to be moved.

And, yes, unless they are connected, they will behave as two structures. You will have to install a seismic joint between the two structures - probably 1 or 2" wide - with a flexible jount.

Mike McCann
MMC Engineering

 

[msquared48]

Interesting idea BA. Thru-bolts or lag screws?

How much movement are you expecting by the way, or do you know?.

Mike McCann
MMC Engineering

 

[MiketheEngineer]

Why not just keep the two "buildings spaced apart - say by 2-3'' and put a "trim" board over space - lightly nailed?? Check max building deflections so they can't bounce into each other.

 

[tmoesabi]

thanks for the replies!


paddingtongreen - I believe their intention with the wording is that at the slab level the connection between structure and foundation needs to be such that the garage can be moved. the foundation will certainly remain.

BAretired - that was my initial inclination as well. Im new to this sport though and was just curious if there was a common method of accomplishing this when dealing with light framed construction...i dont really have the feel yet for what would be "easy" to disconnect if/when the garage is separated.

msquared48 & MiketheEngineer - sorry i dont yet have expected drift values yet, but because of the scale of this project(single family home) I would think the 2-3" gap should work. Ill run the numbers. msquared48, would you mind elaborating on "flexible joint" between the two structures?

thanks again all

 

[BAretired]

Thru-bolts would be easy to remove later.

BA

 

[haynewp]

The isolation joint can be several feet depending on building size and seismic area. You will have to model the 2 structures to find the drag required across the joint if connecting them, which depends on the mass and relative stiffness of the structures.

 

[msquared48]

Where the roof intersects the wall of the house, or another roof, there would need to be a flexible, ususlly curved, waterproof connection that will allow for 360 degree horizontal movement. These are items that are usually specified by an Architect, but sized by the structural engineer. They are more for commercial application than residential, in fact, I have never used one on a house yet.

Try googling "flexible seismic joints at roof", or something similar and see what you get.

Mike McCann
MMC Engineering