17'0" Cantilever truss.

[Ali Abidi]

Dear all,

Could anyone guide me on how to chose preliminary section size of the attached cantilever plan.

your immediate feedback regarding to the matter subjected will highly be appreciated .
Thanks in Advance

Regard's
Ali

 

[jayrod12]

Looking at it from the truss only perspective (i.e. ignoring the fact that your support may be flexible in torsion). I'd be starting by determining an approximate required moment of inertia based on deflection at the tip. Then you can look at what depth of truss would give you that moment of inertia using reasonably sized chord members keeping in mind that a trusses moment of inertia is essentially only due to Ad^2 of the chords.

 

[BAretired]

Your drawings are of poor quality and difficult to understand. You have seven trusses which cantilever 17'. Two on the exterior appear to be fixed to a column. Five appear to be continuous with a very short back span (not dimensioned on plan). These five trusses rely on two beams spanning 46' with a depth of only 18" to provide the required vertical reactions needed to resist the bending moment of each truss.

I believe you will have to come up with a different framing plan. The one shown cannot work as deflections will be unacceptable.




BA