PSI - Issue 47
Ioan Both et al. / Procedia Structural Integrity 47 (2023) 247–252 Author name / Structural Integrity Procedia 00 (2019) 000 – 000
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obtain the basis for new design rules Anapayan et al. (2011). Due to the increased out-of-plane stiffness of the web, corrugated web beams can also be adjusted to accommodate hollow section flanges as presented by Deng et al. (2022), showing an improved post-buckling strength in the performed experimental tests and design methods for shear design suitable for such elements. Steel rectangular hollow flange beams of cold formed profiles were tested to determine the flexural capacity for which numerical analyses showed good agreement, Tondini and Morbioli (2015) Thick tubular sections were used in a numerical study, Matloub et al. (2023), showing bending capacity is found similar in different flange classes but decreases with the reduction of the web class and the capacity of the compact section is higher than the yielding moment. Nomenclature A g percentage total extension at maximum force d distance between the support and the nearest load application point f y yield limit F force recorded by the actuator M bending moment R m tensile strength Compared to the HFB with folded flanges Avery et al. (2000), the beams obtained by welding steel plates eliminate the out of flatness imperfections given in the fabrication tolerances design manual Dempsey, (1993) Another benefit of this section is the capacity to develop plastic deformations. Eurocode 3, CEN (2005)classifies the cross-section function of the capacity to use the plastic deformation of the material. Due to the smaller parts of the outstand flanges or the cross-section parts connected to other parts, internal parts, such beams can be classified as Class 1, thus being able to develop plastic deformations and, theoretically, develop plastic hinges. In this current study an experimental test on a triangular hollow flange beam of welded steel plates subjected to bending is presented. The recordings during the experiment show the lateral deformation of the two flanges which diverge at the moment of instability occurrence. The yielding of material coincides with the loss of rigidity in the moment-deflection curve. 2. Experimental test Lateral torsional buckling is generally eliminated for hollow sections but the material distribution in the cross section is not optimized as for I profiles. The stability of an element is also increased if only the flanges are made of stable profiles. The deformed shape of a triangular hollow flange beam switches from the lateral torsional buckling to lateral distortional buckling, the difference being that for the later case, the cross section changes from the initial shape as presented in Avery et al. (2000). The investigated profile in this study has a triangular hollow section, as presented in Fig. 1, the shape being obtained by automatic welding of steel plates of 100x8, 100x5 and 50x5, respectively, at all the contact points between the plates. Maintaining the inclined parts in exact position while welding, and deformations during the welding, which caused initial internal stresses in the cross section, represented difficulties in the manufacturing process, overcome by initial local welding of the plates, before the automatic welding. The failures expected for the beam are cross-section resistance, web crippling, weld failure, but mostly lateral torsional/distortional buckling, the beam being subjected to bending in a four-point bending setup as presented in Fig. 2a), without any lateral restraints between the supports. It must be mentioned that an out of plane restriction system was used for the load application device (yellow elements in Fig. 2b), but the devices used to transmit the load, the roller in Fig. 3a, were not fixed to the hollow flange beam. A pinned and a roller were used as supports of the two ends of the beam, respectively, having also a fork configuration to constrain displacements of the cross section, Fig. 3b).
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