Wood Shear Wall Details?

[BSE05]

I have a four story wood apartment building using 18" deep prefab floor trusses. In half of the building the interior bearing walls will also be shear walls with the trusses bearing from each side. I was thinking of putting a 1" rim board in between the trusses to act as blocking and shear transfer. Does this make sense? How have others done this?

For the other half of the building the interior shear walls are parallel to the trusses. I am thinking of bring the top plate of the shear wall up beside the truss, right under the bottom sill of the shear wall above. The architect is used to having the shear wall attach to the bottom of the truss? Have others done this?

Thanks for any input.

 

[KBVT]

A simple way to do this is to have the truss manufacturer fabricate truss blocks to slide between each trusses. Just provide the truss manufacturer a typical axial force to be applied to the top chord of the truss block. If your trusses are spaced 24" o.c., then the truss blocks would be 20.5" long typ.

 

[COEngineeer]

I would personally just put a note on the plan saying "Blocking between trussess per truss manuf."

Never, but never question engineer's judgement

 

[DaveAtkins]

Either way is acceptable--rim board (all the manufacturers of floor joists make these) or truss blocks.

And yes, parallel to the trusses you should bring the wall up to the underside of the floor sheathing.

DaveAtkins

 

[SLTA]

you can have the parallel walls stop at the underside of the truss - just have the truss manufacturer design the truss as a drag truss to take the lateral load. you'll have to provide the shear load in the wall. but I agree - it would likely be simpler/cheaper to have the wall continue to the underside of the floor sheathing.

 

[mark1234]

Many buildings like this use pre-fabricated walls. Making the walls 10' may add significant cost.

Typically this is a unit separation wall in the "parallel" condition and a 1 3/4" LSL with simpson clips is an effective way to transfer shear while mindful of fire ratings and keeping wall heights the same.

MDJ

http://www.windspeedbyzip.com

http://www.groundsnowbyzip.com

 

[BSE05]

Great input.

Mark1234 - How are simpson clips used in this application?

 

[mark1234]

SteelyLee,

Simpson angle clips (i.e. A34, maybe LS) are good to transfer shear from the bottom of the LSL to double top plate. Check out the shear values in their catalog.

Many factors play into shear transfer details and cost is certainly one of them. I always try and keep everything as redundant as possible.

MDJ

http://www.windspeedbyzip.com

http://www.groundsnowbyzip.com

 

[msquared48]

SLTA:

This is BAD idea unless the parallel wall is a bearing wall. If it is not a bearing wall, then you will need to use 2X flat blocking at the underside of the floor ply and Simpson DTC clips, or something similar, between the wall top plate and the flat blocking to allow for vertical deflection of the floor joists. Otherwise, you will make a non-bearing wall into a bearing wall. This is a no no.

Mike McCann
MMC Engineering

 

[mark1234]

msquared48,

You are right about inducing loads into trusses at non-bearing points.

This is an apartment complex though so unit seperation walls are not far apart... I'm sure those walls could resist lateral forces.

MDJ

http://www.windspeedbyzip.com

http://www.groundsnowbyzip.com

 

[BSE05]

For the floor trusses parallel condition, I was planning to run the deck plywood between the top and bottom plate and have floor trusses on either side.

Is this a problem? or should I break the decking and use a DTC clip and blocking?