FLAT SLAB DESIGN AND EXPERIMENTAL RESPONSE

Flat slab frames are characterized by a concentration of bending moments and shear forces near the column and by a complex structural behaviour under lateral loading. For this reason, it is important to have adequate code provisions that cover the seismic design of these structures. In Europe, current seismic design code Eurocode 8 does not cover flat slabs that are part of the primary load resisting system, but it does contain general guidance and rules for secondary seismic members. On the contrary, the draft of the new Eurocode 8 for buildings contains provision to verify flat slabs considered in the design as primary seismic elements, but no explicit guidance is provided to verify flat slabs considered as secondary elements (where horizontal actions are primarily carried by a bracing system). In this context, this paper aims to outline a design approach for flat slabs considered as secondary elements and to show its application to the design of a two-story building with primary ductile walls and secondary flat slab frames as a case study. The structure designed in this manner is the object of a full-scale testing program carried out at the ELSA Laboratory at JRC in Ispra, Italy, with the purpose of providing the basis for improved design rules and code development. The results of the design example are verified using nonlinear numerical modelling. An overview of the testing program is presented and the research objectives are described. In designing this structure in accordance with Eurocode 2 and 8, several aspects are discussed and areas for potential improvement of the codes are pointed out