I am designing aluminum screen enclosures in Florida. The aluminum members are thin walled, self mating sections (two C channels that overlap to form a hollow box. THe most common roof shape is a mansard beam. The beam is connected to the host structure at one end and an aluminum post at the other end.
The Florida Bulding Code is requiring simultaneous loading of the roof and wall for design.
For simplicity, I've taken the wall load reaction(wL/2) and applied this force at the end of the mansard beam and designed the beam as simply supported.
If I apply the horizontal force to the end of my beam, I create a moment caused by the eccentricity of the force to the center of the beam. This moment of course reduces the capacity of the beam to handle the vertical load and the allowable spans are reduced.
My question is: Is there another acceptable method of design that would not be so conservative without doing a frame analysis? (There are too many variables and we do thousands of enclosures per year). It appears that other engineers are simply accounting for the horizontal load as an axial load without the eccentricity. This makes a big difference. Am I missing something?
Any suggestions for design alternatives would be appreciated.
The Florida Bulding Code is requiring simultaneous loading of the roof and wall for design.
For simplicity, I've taken the wall load reaction(wL/2) and applied this force at the end of the mansard beam and designed the beam as simply supported.
If I apply the horizontal force to the end of my beam, I create a moment caused by the eccentricity of the force to the center of the beam. This moment of course reduces the capacity of the beam to handle the vertical load and the allowable spans are reduced.
My question is: Is there another acceptable method of design that would not be so conservative without doing a frame analysis? (There are too many variables and we do thousands of enclosures per year). It appears that other engineers are simply accounting for the horizontal load as an axial load without the eccentricity. This makes a big difference. Am I missing something?
Any suggestions for design alternatives would be appreciated.
