Joist diaphragm as lateral deflection bracing?

[drscottuk]

Hi Guys,
I'm designing up a steel frame encompassing 1 exterior face of a house extension (from foundation to rafters).

The house is timberframe.
The steel frame has a balcony connected to it.

I have proved the structure is fine for racking. The steel frame is also fine for the moment load due to the balcony.

The joists are bolted to the steel frame.

I have considered the 1st floor trimmers which are connected to the steel frames posts to be supported in the direction of run of the joists.

There is approx 2KN of lateral reaction acting on the trimmers from the balcony. My question is - how can I prove the trimmers disperse this force (& corresponding deflection) to the racking walls by considering the floor joists as a diaphragm resisting this lateral force?

 

[msquared48]

I can't picture what you are driving at. Can you post a small diagram?

Mike McCann
McCann Engineering