Wood Shear Walls on LVLs

[TORCHMAN]

Lately I have seen some engineers that design wood, 2x6 framed, shear walls on a second floor that do not line up with a moment frame on the ground floor. In an effort to minimize steel, they pick up the tension/compression forces from the shear wall with an LVL beam below, and the shear transfers to a one storey moment frame somewhere else in the house. Is this something you have done or seen?

From an analysis perspective, the LVL should be analyzed to see if it can resist the compression/tension imposed by the shear wall. When it comes to the shear, the system is not a frame so it cannot support it and so the shear is distributed to the moment frame. Below is are a few pictures to try to place some visuals to this.

 

[jayrod12]

Yes this is done often enough. The shear is distributed back into the diaphragm at the bottom of the second floor wall, the diaphragm then distributes that shear to whatever/wherever the lateral force resisting system is in the main floor. If the LFRS is in line with the beam but further down, I would be designing the beam for the load. If the beam is necessary to engage enough diaphragm to take the shear from the wall, again it needs to be designed as such. However, if the bottom of wall to sheathing connection can be made to transfer all of the shear load without needing to use the beam, then it doesn't need to be designed for the T/C forces, imo.

 

[alt0]

Is this something you have done or seen?

Pretty often yes. Some things to keep in mind are that the T/C loads should be amplified by the overstrength factor for the beam design; and the beam should have connections on either end to handle uplift.