Study of steel beam design with web holes

The subject of this diploma thesis is a study of the design of steel beams with large web openings. The thesis consists of a study part and a design-research part.

Beam member with holes

The study part presents a review of the literature and the current state of knowledge in the field of beams with openings. The evolution and application of these elements, typical opening shapes, and their characteristic local failure mechanisms are discussed, including the Vierendeel mechanism and web-post buckling. The rules for designing stiffening (horizontal and vertical plates, stiffening rings), geometric limitations, and a set of design procedures according to the latest generation of Eurocode regulations – standards EN 1993-1-13:2024 and EN 1993-1-14:2024 – are compiled.

In the design-research part, experimental tests were carried out on four steel beams made of IPE300 sections, with circular openings. The elements were divided into two variant pairs – with wide and narrow spacing, where in each pair, a beam without stiffening and a beam with opening stiffening in the form of sleeves made of steel pipes were tested. The beams were loaded in a three-point bending scheme, recording the force, deflection, point deformations, and the strain field using the DIC method. The obtained results were compared with analytical calculations performed in accordance with EN 1993-1-13 and numerical analysis using the finite element method (GMNIA) carried out in the Dlubal RFEM 6 program.

The conducted analyses confirmed that the resistance of beams with openings depends mainly on local failure mechanisms. For beams with wide spacing, the governing mechanism was Vierendeel bending, while for narrow spacing – mechanisms associated with the web-post. It was demonstrated that ring stiffening effectively reduces 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 element. Good agreement was obtained between experimental, analytical, and numerical results, both in terms of resistance and failure modes, which confirms the validity of the standard procedures contained in EN 1993-1-13 for the design of such elements.