Your question is not specific and clear enough to allow intelligent comments.
In general, the AISC Specification and Manual covers most useful information for steel connections design, which I assume is what you are asking about.
I am a ME, not a SE and the material is 6061-T6 aluminum, not steel.
This is for one of several options for a portable structure.
Assume the cross-section of the angle aluminum (2x2x1/4 inches x 4ft. long) is two perpendicular planes. I want to tension load one end in one of the planes and at the other end (4 ft away) balance the load in the other plane of the aluminum angle.
The behavior to which you are referring (attaching one leg of the angle at one end and the other leg at the other end) is called "shear lag." The formulas used to take account for this action for steel angles (and I assume an alumnimum angle would act similiarly just have different rupture and yield strengths) can be found for both welding and bolting type connections in the AISC steel manual. This effect is taken into account in the "U" factor which is used to modify (reduce) the net sectional area when calculating tension rupture capacity of the section.
