Masonry shear wall - diaphragm shear calc

[Roukkia]

I am in the process of the lateral design of a single story, rectangular, masonry shear wall and wood diaphragm building. The shear load is being transferred to the shear walls from the diaphragm through a continuous wood ledger, and anchors into the face of the masonry wall every so often (16-32”).

I am getting tripped up on the diaphragm shear calculation. In an effort to expedite the design, I was going to try and only check one shear wall along each line.

Once I generate the in plane shear in one line of wall, am I able to use the entire length of wall in my diaphragm shear calculation, or should I only be using the length of my single shear wall.

My direct superior has always used the entire length of wall (longer dimension) to collect the shear, and then dump all of the shear into a single shear wall. He was not able to provide a great reason for it. I can see this making sense because I have (2) continuous #5 in my bond beam that are effectively dragging my load down into the shear wall, so as long as the 2 bars can take the tension/compression that a collector normally sees, then we are all good.

Just wanted to see if anyone had any opinions on this. I will post a sketch tomorrow.

 

[XR250]

You need what is called a "collector" which essentially "collects" the distributed shear in the diaphragm and concentrates into a the smaller length of the shearwall. This is usually a continuous member of sorts - such as a properly spliced double 2x. Usually, the diaphragm chord can double as the collector.

 

[DaveAtkins]

The reinforced bond beam can act as the collector. Understand and design for the load path.

DaveAtkins

 

[XR250]

I was under the impression that there was not a full-length masonry wall along the side. After re-reading it, sounds like there is (with openings). Yes, what DaveAtkins said. The concept is the same though - the bond beam is your collector (and maybe your diaphragm chord too)

 

[EZBuilding]

A sketch would be beneficial - I think the condition is a number of different masonry wall piers in a single plane - separate by door or window openings. It appears that the OP is proposing to consider one of the piers as effective in resisting all of the in plane shear across that plane in lieu of distributing the shear load to each pier relative to it's stiffness.

 

[Roukkia]

Thanks Dave, that is the answer I was looking for!

EZBuilding - yes that is correct.

Here is the sketch I promised.