stillfan
Structural
- Jan 18, 2010
- 35
I have a fabric structure that consists of aluminuim material. It is an arched moment frame in the transverse direction and a braced frame in the longitudinal direction. There are rectangular tubes used as braces between the arches.
I have several questions on this. First the arch member is acting as a beam column and in the weak axis - the unbraced length can be taken as the spacing of the rec tubes. Now in the strong axis we are stating that the tubes (which are in the top 1/3rd of the compression flange) is acting as a relative brace. From my understanding both the tube and connection need to be checked for a certain stiffness in order to meet the relative bracing criteria outlined by AISC commentary C6.3 eq C-A-6-3. Now my question lies in that the connection of the tube to the arch (braced frame) is shear only. I have been told that it needs to be a moment frame in order to meet the stability criteria, I disagree, as long as the connection meets the stiffness requirements outlined in C-A-6_3 then it is acceptable, am I incorrect in that statement???
Second, since the structure is aluminuim and connection stiffness is not addressed in the aluminuim design manual is this even an issue? Is there an unwritten law that states that if something is not covered in the ADM that you should use the steel design manual?
I have several questions on this. First the arch member is acting as a beam column and in the weak axis - the unbraced length can be taken as the spacing of the rec tubes. Now in the strong axis we are stating that the tubes (which are in the top 1/3rd of the compression flange) is acting as a relative brace. From my understanding both the tube and connection need to be checked for a certain stiffness in order to meet the relative bracing criteria outlined by AISC commentary C6.3 eq C-A-6-3. Now my question lies in that the connection of the tube to the arch (braced frame) is shear only. I have been told that it needs to be a moment frame in order to meet the stability criteria, I disagree, as long as the connection meets the stiffness requirements outlined in C-A-6_3 then it is acceptable, am I incorrect in that statement???
Second, since the structure is aluminuim and connection stiffness is not addressed in the aluminuim design manual is this even an issue? Is there an unwritten law that states that if something is not covered in the ADM that you should use the steel design manual?
