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Hybrid joints of textile reinforced concrete parts - designed for assembly

Pak, D. / Geßler, A. / Piegeler, D. / Feldmann, M. / Schleser, M. / Dilthey, U.

This paper describes a technique to join precast parts of textile reinforced concrete with hybrid joints. The application of hybrid joints is based on jackets with a welded collar that are inserted into subsequently drilled holes and bonded to the concrete surface. It allows the combination of the advantages of both techniques. In first investigations, it has already been proven that with proper boundary conditions the ultimate resistance of the whole structure is not noticeably reduced by the joints. This motivated a more detailed investigation of hybrid joints which is presented in this paper. The mechanical strength of hybrid joints has been measured for different joint geometries and reinforcement materials. The investigations on hybrid joint techniques have shown that for the ultimate limit state design the decisive design criterion is the layout of the structural elements, rather than the joining elements. With a load carrying capacity of the joints of almost full reference strength of the undisturbed structural element, the joints will remain the part that fails first at the lowest loading, but does not need to be looked upon at the stage of an initial design draft. The observed failure modes documented within this presentation of studies on hybrid joints are identical with earlier investigations on other punctiform connections with bolts. Therefore, the internal-force model derived earlier and further developed in the project based on a truss-framework can also be verified for the extension of these investigations on hybrid joints. A further broadening of the data with regard to the other parameters named above will be necessary to evaluate the model thoroughly. This will also help to concentrate on future analysis with FEM for other applications.