Cross grain bending at interior wall

[Rsd789]

I've seen many example details through textbooks and online sources showing poor wood ledger details attaching to cmu/concrete wall with cross grain bending, however a lot of drawings I've seen across several design firms will still show a similar detail at interior concrete or cmu walls. Do I just have bad luck looking at drawings or is it common to ignore CGB when it comes to interior wind pressure that would be acting on a stair or elevator shaft? If it's the later, is there a max floor height or max load that is tolerable for CGB? I haven't seen anything in the NDS about a CGB capacity so I believe it's just left up to judgement.

 

[Luceid]

Technically speaking - the NDS gives you 0 capacity for tension perpendicular to grain. There are definitely details that can fix this condition - though I've mainly seen this in the tilt up warehouse wall anchorage condition.

 

[phamENG]

Can you post the detail? There are usually minor adjustments or modifications that can be made to reduce or eliminate the tension perpendicular.

 

[Rsd789]

See the example detail below.

 

[phamENG]

If you're looking at shear transfer into or out of the diaphragm, it'll be handled by the perpendicular walls. If you're considering out of plane loading from the diaphragm bracing the wall, probably not a big deal (but some plate washers would probably help). For an exterior wall, I'd put blocking at some spacing with a tension tie.

 

[Rsd789]

Thank you, I think that makes sense. For a condition with framing perpendicular to the wall I imagine tension ties would be an option to resolve CGB or is there a more common method? If tension ties are used, I imagine it would be required at each truss/joist which could add up in cost

 

[phamENG]

Not at every one. Just have to check the load paths and make sure the wall can span between the ties as well as the ties being strong enough to take their tributary load. The tension tie is the common method amongst engineers who pay attention to cross grain bending, so far as I can tell.

 

[driftLimiter]

In plane shear transfer this detail looks okay, but for Out of Plane anchorage of the cmu wall the detail is worthless and in fact prohibited in SDC C - F by ASCE 7-16 Section 12.11.2.2.3.

I routinely add some perpendicular framing or blocking element that with a positive anchor into CMU walls to accomplish the out of plane anchorage in this condition.