Oriana ILNICA, Ph.D. Candidate 40th cycle, University of Trento, DICAM

Tapered members with thin-walled sections, whether with or without openings, are increasingly used in structural engineering. These design solutions reduce the self-weight of buildings, contributing to more resource-efficient and sustainable constructions. However, despite these benefits, the current design rules in Eurocode 3 for tapered members with thin-walled sections and beams with web openings inadequately address several aspects, being overly conservative and limiting the use of these members in structural applications.

The PhD research, part of the European Project TAPERFRAME, aims to bring easy application of the web tapered steel members and structures, both with and without openings, at normal temperatures by providing sound experimental and numerical analysis that will lead to establishing comprehensive engineering design guidelines and recommendations. 
During my PhD, my specific contribution to the TAPERFRAME project included conducting preliminary numerical investigations using the finite element software Abaqus for the definition of the test specimens characterised by different slenderness, taper ratio, etc. as shown in Figure 1. The numerical model incorporates all relevant parameters, such as geometrical imperfections (local and global) and material imperfections (residual stresses). A linear 4-node shell element model was adopted. Based on the preliminary analysis outcomes, the entire test set-up will be designed and a series of experimental tests at normal temperature on tapered members with solid and cellular webs, along with two types of moment connections connected to cellular beams, will be performed (see Figure 2). These experimental data and parametric analysis with calibrated numerical models will form the basis for developing new design rules.

Figure 1. Collapse of a tapered beam without openings in bending + axial load - Abaqus

Figure 2. Test set-up of tapered beams without openings in bending + axial load