The influence of vertical shear on the hogging bending moment resistance of ComFlor composite slabs

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.