horizontal forces acting on top of CLT walls (L shaped house)

[greznik91]

This is the 1st time im designing structure like this, so I hope for some advices.

I have residental building with CLT bearing walls (cross laminated timber). Above walls are timber beams for ceiling (1 m apart) + plywood.
Resident building has 'L' shape (top view).

Since CLT walls can only take vertical loads, I have to connect roof with some kind of ties (horizontal forces acting on top of the walls). So I was thinking to use timber beams above walls as ties that take care of tension loads (horizontal loads from roof rafters) so walls see only vertical loads. That means that beams above walls are loaded vertically (ceiling loads) + tension loads (from roof). Thats what Im planning to do in areas shown in attached image bellow (view 1-1 and 2-2). But since I have the L shaped building, I am asking what to do in the middle ('?' area). I am also expecting some large horizontal forces at the support of hip beams (yellow beam in image) acting on the walls.

 

[jayrod12]

your CLT walls will also see the lateral load, i.e. your roof diaphragm loads so make sure you detail the connections between the roof joists/beams and the walls appropriately for those loads as well.

 

[n3jc]

walls will see horizontal forces perpendicular to their plane (wind load)regardless... but not loads from self weight and snow from roof since you have timber beams + plywood (acts as some kind of diaphragm)on top of walls that will catch horizontal forces (tension forces in timber beams - ceiling). Seismic forces and wind forces will be distributed based on walls stiffness.

 

[molibden]

In this configuration with two roof beams you will get minimal tension force in the ties or even compression in the upper one. Put columns on top of CLT walls to support roof beams and also valley/hip beam. Rafters bear on roof beams and external walls. Then you need to think about stability of the roof - maybe some kind of OSB or wood-based panel sheathing, braces.. You need to transfer your lateral loads from roof to CLT walls.
Your model seems ok, there are only columns missing to support roof beams.

 

[greznik91]

thank you for replies.

roof beams with column supports and bracing (there will be sheating on top of rafters):