wood truss floor diaphragm boundary element

[jeng123]

If you have a wood diaphragm comprised of wood floor trusses bearing on an intermediate stud bearing wall, how and what is engineered as your diaphragm boundary element? See attached detail. Thanks

 

[abusementpark]

The top chord of the truss would be a boundary element. You could add 2x blocking and that could be a boundary element for a blocked diaphragm.

 

[jeng123]

abusementpark - a boundary element needs to transfer both compressive & tensile forces. How will discontinuous blocking work for tensile forces? That is why double top plates are typically specified with minimum lap splices right?

 

[msquared48]

Yes, it could be the wall double top plate with appropriate splices, or it could be continuous metal strapping over the solid blocking or over the plywood itself. Either will work.

Mike McCann
MMC Engineering

 

[RFreund]

While I agree with the statements above -

For the case that you have attached I don't think that this interior/intermediate wall would be part of a chord member (taking compression and tension). It may be an intermediate shear wall in which it would need to take shear from the diaphragm in which case I would think blocking without strapping would be ok. However because the plywood deck is continuous over the intermediate wall the tension and compression cord members will be at the exterior walls (or where the plywood is discontinuous) in which case you would need a strap/blocking or rim board.


EIT

 

[msquared48]

rfreund:

If the detail was at the juncture of a drag collector extending to the shear wall and in a seismic zone, blocking with strapping will be required.

If only wind, then, generally only the blocking, unless there is a huge suction force on the leeward wall.

Mike McCann
MMC Engineering

 

[abusementpark]

abusementpark - a boundary element needs to transfer both compressive & tensile forces. How will discontinuous blocking work for tensile forces? That is why double top plates are typically specified with minimum lap splices right?

Are you talking about chord members or boundary elements of a intermediate diaphragm panel?