The shape factor is the ratio of the plastic section modulus Z to the section modulus S ( Zx / Sx ) or (Zy / Sy). It is basically a measure of how much inelastic stress you can withstand above and beyond yield.
Hope that helps.
Gerard Madden, P.E.
Middlebrook + Louie, Structural Engineers
71 Stevenson Street, Suite 2100
San Francisco, CA 94105
>>> Stanley_P_Johnson(--nospam--at)dot.ca.gov 02/06/01 04:41PM >>>
For weak axis bending of I-shaped members, the commentary mentions that one
reason for an allowable stress of 0.75*fy is the favorable shape factor for
I-shaped members bent about their weak axis. My question is, "What is a
shape factor and what influences a shape factor?"