Study on Design of Steel Beams with Openings in Web

The subject of this thesis is a study of the design of steel beams with large web openings. The thesis comprises a state-of-the-art review and a design-and-experimental part.

Beam with Openings

The review part presents a survey of the literature and the current state of knowledge concerning beams with web openings. The evolution and application of these members are discussed, together with typical opening shapes and the local failure mechanisms characteristic of them, including the Vierendeel mechanism and web-post buckling. The detailing rules for reinforcement (horizontal and vertical stiffener plates, ring stiffeners) are compiled, along with the geometric limitations and the set of design procedures according to the latest generation of Eurocode provisions — standards EN 1993-1-13:2024 and EN 1993-1-14:2024.

In the design and experimental part, experimental tests were carried out on four steel beams, fabricated from IPE300 sections, with circular web openings. The members were divided into two variant pairs — with wide and narrow spacing — whereby in each pair, an unreinforced beam and a beam with openings reinforced by steel-tube sleeves were tested. The beams were loaded in a three-point bending configuration, with force, deflection, discrete (point) strains, and the full-field strain distribution recorded using the Digital Image Correlation (DIC) method. The obtained results were compared with analytical calculations performed in accordance with EN 1993-1-13 and with a numerical finite element analysis (GMNIA) carried out in the Dlubal RFEM 6 software.

The analyses performed confirmed that the resistance of beams with web openings is governed primarily by local failure mechanisms. For the beams with wide spacing, the governing mechanism was Vierendeel bending, whereas for the narrow spacing the governing mechanisms were those associated with the web post. It was demonstrated that ring reinforcement effectively reduces the stress concentration at the opening edge and increases the Vierendeel bending resistance, bringing the behavior of the weakened beam close to that of a solid-web member. Good agreement was obtained between the experimental, analytical, and numerical results, with respect to both resistance and failure mode, which confirms the validity of the standard procedures given in EN 1993-1-13 for the design of members of this type.