2. Dimensions of sections

2.1Masses

The masses per metre have been calculated assuming that the density of steel is 7850 kg/m³.

In all cases, including compound sections, the tabulated masses are for the steel section alone and no allowance has been made for connecting material or fittings.

2.2Ratios for local buckling

The ratios of the flange outstand to thickness (c_f / t_f) and the web depth to thickness (c_w / t_w) are given for I, H and channel sections.

	for I and H sections
	for channels
	for I, H and channel sections

For circular hollow sections the ratios of the outside diameter to thickness (d / t) are given.

For square and rectangular hollow sections the ratios (c_f / t) and (c_w / t) are given where:

and

For square hollow sections c_f and c_w are equal. Note that these relationships for c_f and c_w are applicable to both hot-finished and cold-formed sections.

The dimensions c_f and c_w are not precisely defined in EN 1993-1-1 and the internal profile of the corners is not specified in either EN 10210-2 or EN 10219-2.  The above expressions give conservative values of the ratio for both hot-finished and cold-formed sections.

2.3Dimensions for detailing

The dimensions C, N and n have the meanings given in the figures at the heads of the tables and have been calculated according to the formulae below. The formulae for N and C make allowance for rolling tolerances, whereas the formulae for n make no such allowance.

2.3.1UB sections, UC sections and bearing piles

2.3.3Parallel flange channels