Chapter 14: Annex D (Normative). Composite beams with web openings

Openings in steel webs are the subject of both Annexes D and E, as explained under ‘Scope’, below. This chapter corresponds to Annex D of EN 1994-1-1, which has the following clauses.

Openings were being provided in the webs of steel I-beams long before the Eurocodes appeared, but no design rules for them were included in either Eurocode 3 or 4. Beams have two main types of opening: individual holes for the passage of service pipes and ducts, and regularly spaced openings continuous along the span. Those known as ‘castellated beams’ have a regular repeated pattern of hexagonal openings, and a depth about 50% greater than that of the original I-beam. Their bending resistance and flexural stiffness are greater than those of the original beam. They have been widely used for long lightly-loaded spans, whether service runs are needed or not. Castellated beams were followed in the 1990s by ‘cellular’ beams, which typically have regularly-spaced circular web openings over most or all of the span (Figure 14.1).