horizontal forces acting on a RC parapet wall and rafter tie

[greznik91]

I have a new masonry building with RC slab and a timber roof. Span of rafters is quite large.
RC slab is not across the whole storey.

case A: I make a RC parapet wall (250 mm wide) that is designed as cantilever (because there are vertical + horizontal forces on top of a wall because of rafters/roof), I anchor RC parapet wall into RC slab (150 mm thick) which is capable to carry tension loads (from roof to parapet to slab).

case B: since I dont have a RC slab above masonry walls acroos the whole plane I make a rafter tie which is able to carry tension load from roof. the wall can be masonry since there will be only vertical load acting on it (because tension is in the tie).

what is your opinion on my solution? do you agree?

 

[XR250]

Either solution should work if designed correctly. Case B is more efficient but may be less aesthetically pleasing if that is an issue.

 

[KootK]

Both conditions work for me. You can probably omit the collar ties. Detailing will be especially important for case A. You'll have to grab the tension bars at an opening joint while transferring your moment down into the masonry.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[greznik91]

You'll have to grab the tension bars at an opening joint while transferring your moment down into the masonry.

I was thinking to reinforce it like this:

 

[KootK]

Nice. Probably a little more intensive than I'd have done but, then, I don't know the loads. I'd imagined that you'd want to transfer your moment into the wall below rather than into the 150 slab.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.