In plastic analysis of steel structures, what is the shape factor for a rectangular cross-section?

Explanation

Shape factor (S) is the ratio of plastic section modulus (Zp) to elastic section modulus (Ze). For a rectangular section, Zp = bd^2/4 and Ze = bd^2/6, giving S = 1.50. For an I-section S ≈ 1.12 to 1.15, for a solid circular section S = 1.70, and for a diamond section S = 2.0.