Composite slabs are designed to transfer loads in one direction e.g. the longitudinal direction of the ribs. To reduce the deflection, it is useful to realise a continuous slab with at least one intermediate support. At the intermediate support in addition to a hogging bending moment a rather large vertical shear force will act. For the verification of the combination of vertical shear and bending clause 9.7.5 of EN1994-1-1 [1] refers to clause 6.4.4 of EN1992-1-1 [2]. However in EN1992-1-1 there is no requirement related to interaction between vertical shear and a sagging or hogging bending moment. Implicitly this implies that interaction may be neglected and that bending moment and shear force may be verified separately. In practice checking authorities not always accept this interpretation of the code and require proof that interaction may be neglected. So Tata Steel Panels and Profiles with Dutch Engineering r.i. BV commissioned Stevin II laboratory of Delft University of Technology to carry out a research program to investigate this interaction. A test program was carried out to gain more insight in the interaction and to find out whether design calculations should take into account M-V interaction when applying the ComFlor series. Two series of respectively three and two test specimens were conducted, namely on ComFlor 210 (TS1 up to TS3) and ComFlor 75 (Tata Steel Panels and Profiles reference ComFlor 60) (TS4 and TS5) produced by Tata Steel Panels and Profiles and supplied by Dutch Engineering r.i. BV in the Benelux. A second point of interest is the contribution of the steel deck to the vertical shear resistance. The reference in clause 9.7.5 of EN1994-1-1 to EN1992-1-1 without mentioning EN1993 causes that in practice only the contribution of the concrete rib is taken into account, the steel deck is neglected completely. This is, of course, a simplification of the actual behaviour. @en

This paper is about the laser measurements as part of the research on the distribution of a certain amount of steel over the flanges and the web of an I-shaped plate girder to achieve the maximum bending moment resistance [1]. In many steel structures standard hot-rolled sections are used. These sections are divided into specific types in Europe and similar profiles in the USA. The range of hot-rolled sections is limited and therefore fabricated plate girders are used. Double symmetric I-shaped plate girders are built up with steel plates for the top and bottom flange and the web, welded together to a cross-section. Using this type of plate girders, a high degree of optimisation of material use is possible by using different plate thicknesses and widths for the flanges and thickness and height for the web. In the thesis the main topic for optimisation is the bending moment resistance of a plate girder. The maximum bending moment resistance appears for plate girders with a lot of material in the flanges and with a large web height. The web thickness has to be as small as possible and so the web slenderness has to be as large as possible. The limitation of the web slenderness is according to the Eurocode and the American standard based on flange induced buckling. The web of cross-section class 4 buckles and this buckling is during experiments measured by lasers. This paper gives an overview of the results of the laser measurements. Based on these measurements, it is concluded that flange induce buckling is not a limitation for the web slenderness. High web slenderness can be applied and the bending moment resistance increases enormously and the stiffness increases even more. Because of this, the use of HSS becomes of high interest. @en

In a material economy driven plate girder design, the lever arm between the flanges will increase. This leads to higher stiffness and bending moment resistance, but also to an in-crease of the web slenderness. This means that high strength steels can be used leading to a large reduction of the steel consumption. However, Eurocode 3 [3] restricts the web slender-ness based on the formula to avoid flange induced buckling, derived by Basler [2]. Experi-mental and theoretical research by Abspoel [1] conducted at the Stevin II Laboratory of Delft University of Technology, shows that this formula is too conservative. Ten unstiffened plate girders with high web slenderness’s are tested, focussed on flange induced buckling.@en