Hip rafter point load calculation

[dcwalker]

Hi there

I need to install an opening in an internal wall that bears a point load in the form of a strut that supports a hip rafter.

To calculate the appropriate lintel size for the opening, I need to know what roof loads the strut is supporting.

Can anyone offer any help calculating the roof load width and roof area supported by a strut that supports a hip rafter?

 

[XR250]

No offense, but if you are struggling to calculate the point load, you will likely have a similar struggle calculating the correct beam size.

 

[RobertHale]

My suggestion, Take your roof plan, layout the roof framing and then draw your tributary area over the plan. That will give allow you to get he loading diagram you need to analyze the hip (assuming it is a simple beam, read post at the end) and get your reactions.

___________________
- Robert Hale, PE, SE

 

[JStructsteel]

Hip rafter, or the hip beam?

You in a snowy area? Windy area?

 

[Scipio_Wright]

Like RobertHale said, a good sketch goes a long way.

Figure out how much of the roof area the strut will support.
If the strut is supporting a single rafter, its tributary area will be half of that rafter's.
If the strut is supporting a beam that supports rafter (an underpurlin), figure out what length of the beam the strut is supporting, then the tributary width of the beam, and multiply the two together.

Apply snow loads and wind loads per ASCE 7. Use C&C for the wind loads, since you're checking a single component (the strut). Don't forget the roof live load.