General

The classification of the cross section is in accordance with EC3 Cl. 5.5 Table 5.2

A steel non-composite beam can be classified as:

• Plastic Class = 1

• Compact Class = 2

• Semi-compact Class = 3

• Slender Class = 4

Class 4 sections are unacceptable and are either failed in check mode or rejected in design mode.

Implementation of the below clauses is as follows:

• Classification is determined using clause 5.5.2 (6) and not 5.5.2 (7).

• Clause 5.5.2 (9) is not implemented as clause (10) asks for the full classification to be used for buckling resistance.

• Clause 5.5.2 (11) is not implemented.

• Clause 5.5.2 (12) is not implemented.

The note at the end of clause 5.5.2 is not implemented. A brief study by CSC (UK) Ltd of UK rolled UBs and UCs showed that flange induced buckling in normal rolled sections is not a concern. No study was undertaken for plated sections.

Hollow sections

The classification rules for SHS and RHS relate to “hot-finished hollow sections” and “cold-formed hollow sections”.