Residential shear walls

[DRsquare]

I am working as a plans examiner, and have seen several designs using interior shear walls. These are generally connected to trusses parallel to the shear wall, but not necessarily directly over the shear wall. I have started requiring a sign off by the truss engineer, as well as a foundation footing, but because ot the desire for so many windows, the placement of shear wall is not particulary balanced on each side. What should I look for and what criteria should I use for rejection of design. The other thing that eats at me is that they specify manimum nailing (8x4, or 8x3) for a portion of the wall, which is then used for the all the walls. How detrimental is this to the studs. I have noticed that some manufactures are suggesting moment resistanting connections to garage door beams, and comments on this practice?

I realize thic covers too many topics, I'll break it up if you think I should. I feel we are playing catch up as it is, we just started asking for horizontal forces on truss connections in a ddition to just uplift, but many other counties do not even do that. I wish it was emphasized more in the code.

But thanks for your comments.






Thanks for you help.

 

[sundale]

Whenever I have an interior shear wall parallel to plated wood trusses, I typically balloon frame the the top of the shearwall to be directly under the roof sheathing. The top plate of the shearwall should continue all the way across the diaphragm as a drag strut (collector element) to prevent diaphragm tearing and to ensure deflection compatibility for all the shear walls being loaded simultaneously. The drag strut needs blocking and kickers to inhibit buckling if it is loaded in compression.

You can also use a plated truss to transfer drag forces from the diaphragm to the shear wall. The engineer of record (EOR) should identify these axial forces in the truss top chord that need to transfer through the truss webs to the truss bottom chord. The attachment of the truss to the shearwall and the permanent bracing of the truss should also be specified by the EOR. The truss manufacturer needs to design his truss chords, webs, and panel point connections for the extra wind or seismic forces.

This is usually such a hassle for me as the EOR that (when possible) I simply design my own wall, connections, and drag strut in lieu of spoon feeding forces to the truss guy and then checking his design. Note that you have to use the trusses as a drag strut if the drag strut crosses pendendicular to a roof ridge. This is due to the fact that there is nothing to resolve the vertical component of the drag force with simply a flat double top plate.