The effective-width generator

The effective width is the rectangle with the same area under it. Longitudinal stress across a flange overhang of 3 m on a span of 20 m, as a fraction of the stress at the web. It is 100% at the web and has fallen to 76.5% at the free edge, because stress reaches the flange only through shear along the junction and the far parts of it lag. The shaded rectangle is the effective width: 2.531 m at the full web stress, carrying the same force as the whole 3 m of real flange. That is 84.4% of the width drawn, so the peak stress is 1.185 times what plane sections would have said, and 18762 mm² of the two overhangs — 15.6% of 120000 mm² — is material that is there, and paid for, and hardly working.

1 essay calls effective-width. The drawing above is what it returns with no arguments at all; every call below passes it something, because a placement that passes nothing draws whichever member of the family the generator happens to default to rather than the one its essay argues about.