Transfer lateral force between offset floors 2

[Dave169]

I am reviewing plans for a friend in which the upper floor of a Prairie style house is supported by beams and columns and is located over the middle of the lower floor. The floor diaphragm for the upper floor does not extend to any exterior shear walls on the lower floor and there are very few internal walls below the floor diaphragm that could be used as internal shear walls.

Lateral wind forces will require straps between the end posts of the upper shear walls and the beams below. I can transfer needed uplift forces for the upper floor and roof to the foundation by specifying appropriate connection for the supporting beams and columns. I assume the design must also transfer the lateral shear force from the upper floor to the lower shear walls as well. Does anyone have any idea how to transfer the shear forces from the upper floor and roof to the lower exterior shear walls without some sort of interior shear walls below the upper floor?

A roof diaphragm connects the upper walls to some of the lower shear walls but it has many dormers with valleys and hips and I do not know how I could model this and determine needed connections.

Thanks for any advice you may have.


David

 

[oldrunner]

It appears that you need to establish a load path from the roof to the foundation. Somehow, obviously, you have to ge the horizontal forces dragged over to a supporting stiff element. Can you hide some sort of the steel frame anywhere?

 

[jen4950]

I agree- you need to determine your load path..

There are many ways to take care of the path- moment frames, braced frames, shear walls in all their forms..

 

[Murali27]

Hi Dave

Can we have some collectors (beams) to the lower interior shear walls from the upper floating shearwalls?

You can send the sketch indicating the situation. jbgm_27@rediffmail.com

Thanks
Murali G