Design of composite dowels according to the new national technical approval.

Composite dowels are known as powerful shear connectors in steel-concrete-composite girders. More and more they are used in practice especially for prefabricated composite bridges. Advantages over other shear connectors are in particular the increased strength, the sufficient deformation capacity even in high strength concrete and the simple application in steel sections without upper flange. However, missing provisions in standards for composite dowels with the economic clothoid and puzzle shape have led to retentions of clients and delays in the approval process. Hence, the aim of the recently finished research project P804 founded by FOSTA-Research Association for Steel Application was to solve open questions concerning these innovative shear connectors and to prepare a national technical approval available (Allgemeine bauaufsichtliche Zulassung - AbZ) for any design office and construction company. In this paper design concepts for ultimate limit state and fatigue limit state, structural design principles and instructions for production and construction are presented and background information are given.