Marcin Abramski, Thomas Friedrich, Wolfgang Kurz, Jürgen Schnell

• In modern buildings various installation systems for HVACR, electricity and communication have to be installed. An innovative approach to this requirement is to include the necessary space in the slab construction. Using this approach a new composite slab system has been developed. It consists of two concrete slab layers on top and bottom side of the construction that are connected with vertical steel webs. Precast slab elements with pre-assembled HVACR equipment are installed at site. For improvement of performance in SLS and ULS the system is prestressed without bonding. To optimize the economics the shear connection between concrete and steel shall be realized with concrete dowels. Due to the installation of pipes and ducts various web openings have to be incorporated in the design of the slab system. Secondary bending moments cause considerable additional loads to the steel web and especially to the concrete dowels connecting steel and concrete. Therefore new types of dowels shall be developed to improve load capacity and ductility both for vertical and horizontal shear forces. Results of the new development on concrete dowel's geometry will be presented. Also a short overview of the first application of this slab system in a multi-story building will be given.