Tragwirkung von Betondübeln für Sandwich-Verbunddecken mit großen Stegöffnungen

Transferring of loads by concrete dowels in sandwich composite floors with large web openings.

Modern conceptions of economically and ecologically sensible HVACR installations in residential and public buildings require their integration in the structure. The paper presents experimental investigation on precast sandwich composite steelconcrete floor with spans of up to 16 m and width up to 3 m, in which the HVACR installations (heating, ventilation, air conditioning, electricity etc.) are integrated already at a concrete plant.
The floor consists of two 10 cm thick concrete slabs on both top and bottom sides with 20 cm high blank space between them. Both slabs are connected with vertical steel plates as well as reinforced concrete webs. The floors are post-tensioned prestressed. There are high local forces being transferred between the concrete slabs and the steel web. A standard solution for joining the both structural elements is the application of horizontal headed studs. An alternative solution was investigated: puzzle-formed concrete dowels at both edges of the steel web. The concrete dowels were optionally confined with spiral reinforcement. A special attention was focused on the load-carrying capacity of the floors in the area of large web openings. The floor system with its technical aspects is presented in the paper, as well as the experimental investigations carried out on the floor and separately on the puzzle-formed concrete dowels.