Does anyone know why the ends of the bottom chord of my truss fails when it has double angle section L75x75x6 LD, while when I use the single angle section L75x75x6, it passes? as per the output, the members fail in flexure compression and tension (eq. H2-1). I just wonder why it fails when it has larger section and the critical load for its failure is from upward windload.Attached is the staad file for reference.
WMF-ROOF_REVISED JULY 11.std
I think this is due to the orientation of the single angle section. If you would assign the Beta Angle as 45 degrees to the single angle (to make its geometrical axis parallel to global axis as in double angle), then that single angle would fail as well.
Answer Verified By: Lay Abaigar
already changed it, you're right, it fails now when I corrected the orientation of the single angle section. This means I need to increase the size of the section of the bottom chord.