Live load reduction on curved roof 1

[Iasonasx]

I am new to this so I hope my question does not seem too obtuse. I see the definition in ASCE 7 (4.8.2 - last two lines) stating that the "F" factor becomes rise to span ratio and will be multiplied by 32. Now above that, for non curvilinear structures it defines "F" as a inches of rise per horizontal foot (i.e F=4 if we have 4"/ft). So in case we have a span (that means the whole diameter of that dome ringt?) of let's say 30ft and the height at the midpoint is 5ft, that would make my "F" factor equal to ....(5/30)*32=5.3333. Please correct me if I am wrong. I am actually trying to simplify that to a simple factor that seems to be 1.3333 of the inches rise per feet run that the code defines for non curvilinear structures.
Thank you

 

[DST148]

@Iasonasx - Yes, you are right - For curved surfaces where R is Rise in feet and L is span in feet
F = R / L [non-dimensional] * 32 (As given in the code)
= (Number of inches of rise per foot} * 1.3333 - Your simplified formula

 

[PicoStruc]

You reduce the load of the roof ?

We don't reduce roof tribitary area because snow loard is not reducible !

 

[woodman88]

For some of us, in the USA, there are areas that do not receive snow. In these areas the roof minimum live load can be reduced for area and/or pitch to a certain minimum live load. Per the IBC/IRC building codes.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[PicoStruc]

By curiosity, that is the minumum live load on a roof ? Here in the north.. it's 20 psf if the snow don't govern.

 

[woodman88]

The minimum 20 psf ordinary (flat, pitch and curved) roof live load may be reduced down to a minimum of 12 psf for a combination of slope and/or area, per the IBC building code.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.