Experimental and numerical modal analysis of a lightweight steel-concrete composite slab supported by cellular beams

The continuous demand for an even more efficient use of materials and economical construction methods has stimulated the development of new types of lightweight construction components. Because of their usually rather complex geometry, it is not feasible to model them in very fine detail. Much more convenient is to model them by simpler elements with equivalent properties. Another problem with these structures is their dynamic behaviour: due to their low mass, they are more vulnerable to dynamic excitations. In this paper, the case of a composite slab, existing of an orthotropic steel-concrete slab and cellular beams, is investigated. An attempt is made to derive equivalent geometrical and material orthotropic plate properties for the steel-concrete slab. The supporting cellular beams are replaced by solid beams with energetically equivalent stiffnesses. With these equivalent elements, a simplified FE-model of the structure is built for modal analysis. In order to improve the correspondence between the FE-model and the real structure, this model is updated, making use of measured modal data. The results of the detailed FE-analysis are compared with approximate manual calculations of the stiffnesses.