Wood - Masonry Combo Lateral Force Resisting System 1

[RFreund]

I was looking for some direction on how any of you would approach the design of the attached addition.

Scope:
There is an existing office building which is masonry. They don't want to try and reinforce the existing building so we must keep the new and existing seperate. One side of the new building is a 2-story wood framed structure the other side is a one story (3 sided) masonry structure. I need to design the LFRS.

I was thinking I could ignore the wood side and design the Masonry for full load, then ignore the masonry and design the wood for full load. This design will most likely be controlled by wind as it is in low seismic area.

I appreciate any input, Thanks.

EIT

 

[ash060]

Why not do the whole bottom floor in masonry and the 2nd floor in wood? It is not uncommon.

Splitting the system in half just doesn't seem the best way to do it.

If the diaphragm is flexible design with trib area

 

[RFreund]

Yeah I would agree. I could possibly recommend that, however I think we were brought into this project relatively late in the game. I think the arch realized they would need to submit calcs for the lateral system and thats when they came to us. Assuming the don't want to change...

I believe the diaphragm will be flexible which makes designing the walls for the north south forces relatively straight forward. However when looking at the East-West forces thing start to become a little foggy.

EIT

 

[msquared48]

I would treat them as two different structures, one two story wood frame, and the other a one story masonry, with adequate separation betwseen new and existing to prevent hammering.

They will have two inmerenty different frequencies. Do not connect them unless you totally rely on the new masonry for all the lateral forces, acting as connected to the existing structure.


Mike McCann
MMC Engineering
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