Z20019 - Section Properties

Z20019 has a mass of 5.74 kg/m, tabulated to Continental Steel. A 12 m length therefore weighs about 69 kg, which is the figure to use for a steel take-off or when checking a lift.

Z20019 has a depth of 203 mm, a width of 79 mm, a wall thickness of 1.9 mm, with a cross-sectional area of 7.13 cm². These are the nominal dimensions from Continental Steel; rolling tolerances apply to the delivered section.

The elastic section modulus about the major axis, Wel,y, is 19.1 cm³. Use it with M_el,Rd = Wel,y x f_y / gamma_M0 for an elastic check.

The second moment of area about the major axis, Iy, is 7.45 cm⁴, and about the minor axis Iz is 21.9 cm⁴. Iy is the value deflection depends on - for a simply supported beam under a uniform load, the midspan deflection is 5wL⁴/384EIy - so on spans where a deflection limit governs rather than strength, this is the number that decides the section.

iy is 84.3 cm about the major axis and iz is 145 cm about the minor axis. Column buckling is governed by the SMALLER value: the slenderness is lambda = L_cr / i, so with iz = 145 cm a 14.5 m effective length already gives lambda = 100. Minor-axis buckling almost always controls unless the weak axis is restrained.