Light gauge load bearing fire walls

[MrJB]

All, does anyone have advice on designing load bearing fire walls and connections with light gauge? Understand that the fire protection is mainly provided by a fire resistant plasterboard and that the temperature in the flanges differs which causes thermal bowing and reduced capacity. Are there any good resources on the temeperatures that occur after certain times and the temperature difference between flanges? Have reviewed the AS4600 approach yet it appears there is extra information thats required to plug into the equations.

Is the general approach with any exposed connections to coat them in an intumescent coating with suitable fire rating to match the FRL of the wall?

Any assistance or guidance would be appreaciated.

 

[milkshakelake]

I'm not familiar with your codes. But in USA where I practice, load bearing walls which are fire rated need to be sheathed in something like 2 layers of 5/8" fire rated gypsum board. Once that's done, no additional calculations for reduced capacity are needed. There are no exposed connections to coat with intumescent paint; everything is covered. Any holes in the wall for pipe penetrations are sealed with colored firestopping.

So I'm not considering the sheathing to "mainly" provide fireproofing. I'm considering it to provide "all" fireproofing.

 

[EngDM]

But in USA where I practice, load bearing walls which are fire rated need to be sheathed in something like 2 layers of 5/8" fire rated gypsum board.

I agree with the statement above. The studs aren't the rated element, the wall assembly aside from the studs is.

However, if you are worried about the potential heat transfer into the studs making the studs weak you can check out the CAN/ULC S101 fire tests, I think they have some information about how much heat gets through the assembly.