Hinterschnittdübel werden in kerntechnischen Anlagen zur nachträglichen Befestigung von maschinentechnischen Komponenten an Stahlbetontragwerken eingesetzt. Um die Integrität der Komponenten auch bei außergewöhnlichen Einwirkungen wie Erdbeben zu garantieren, müssen die Dübel eine ausreichende Tragfähigkeit aufweisen. Für die Annahme einer ausreichend starren Befestigung müssen darüber hinaus bleibende Dübelverschiebungen in engen Grenzen gehalten werden, da Dübelverschiebungen unmittelbaren Einfluss auf die Lastverteilung und ‐übertragung der Rohrhalterungen haben. Zum Nachweis von Tragfähigkeit und Verschiebungsverhalten von sicherheitstechnisch wichtigen Dübelbefestigungen werden Zulassungsversuche nach europäischen und deutschen Richtlinien bei unterschiedlichen Belastungen und bei unterschiedlichen Rissbreiten bzw. Risskollektiven durchgeführt. Um die Übertragbarkeit des Verschiebungsverhaltens bei Zulassungsversuchen auf realitätsnahe Belastungsbedingungen zu überprüfen, werden Ergebnisse von Zulassungsversuchen und Ergebnisse von großmaßstäblichen Erdbebenversuchen miteinander verglichen.

In nuclear power plants, non-structural systems such as piping are often connected to concrete floors by post-installed anchors. During an earthquake, the anchors have to transfer the dynamic loads between the structural and mechanical components of the power plant. The dynamic behavior of the coupled system concrete-anchor-piping is not only governed by the main components but also by the load-bearing behavior of the anchors and the dynamic behavior of pipe supports. Stiffness reduction of supports can lead to contact problems. Impact loads due to gaps between the anchor plate and concrete floor occur when the anchors show significant displacements. Uncertainties concerning possible interactions of the coupled system concrete-anchor-piping can lead to unexpected failure modes during the system response. To investigate these possible interactions, experiments and detailed numerical simulations regarding the dynamic behavior of the coupled system concrete-anchor-piping are carried out. Results of experiments and numerical simulations on the seismic performance of a mock-up consisting of piping, anchors and a structural concrete member subjected to crack cycling are presented.

The load bearing behavior of piping systems depends considerably on support distances and stiffness as well as cross section characteristics. Stiffness of supports can often be defined only with difficulty by applying simplified procedures or guidelines based on assumptions. Load cases can be estimated quite well, but the safety assessment of a piping system can only be as reliable as the system model can realistically describe the present support stiffness or imperfections e.g. local wall thinning. As a consequence, the prediction of the system response may be poor. It is likely that calculated frequencies differ from natural frequencies determined experimentally. These frequency shifts lead to unrealistic predictions of stress analysis. Examples for overestimations and underestimations of stress analysis are given regarding the load case earthquake, depending on whether the frequency shift runs into or out of the plateau of the applied floor response spectrum. The influence of local wall thinning on modal characteristics is investigated. Conservative estimations of the influence on the load bearing behavior regarding severe local wall thinning are given. For fatigue checks the linear response of an experimental piping system is calculated and safety margins are demonstrated by comparing calculated with experimental results.

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In nuclear power plants, post-installed anchors are used for connections between concrete structure and non-structural components such as piping systems. Piping is usually connected to concrete fastenings by pipe hangers. Dynamic loading during an earthquake leads to dynamic interactions between concrete structure and non-structural component. These dynamic interactions result in dynamic loads which have to be transferred by fastenings such as anchor plates with post-installed anchors. Besides the vibrational behavior of the subsystems, the dynamic behavior of the coupled system concrete-fastening-piping is also influenced by the load-bearing behavior of the anchors. At anchor loads close to ultimate load, the load-bearing behavior of anchors is highly nonlinear due to plastic deformation of the anchor bolt and cracking of the concrete. Additionally, permanent displacement of anchors which already occurs at smaller loads can lead to change of pipe hanger stiffness characteristics and nonlinear vibrations of the component. For an ongoing research project, various numerical design calculations are carried out for a test set-up. The test set-up is designed to study the dynamic interactions and effects mentioned above. In order to investigate the necessity for a coupled analysis of the structural and non-structural part of the test set-up, one study in this paper deals with the effect of coupling/decoupling on calculated natural frequencies and pipe hanger loads. For simulating the nonlinear behavior of the fastening during seismic loading, anchor models with different levels of complexity were developed which were then implemented in a large-scale finite element model of the test set-up. Comparative seismic analyses in the time domain with different anchor models are presented which are carried out as preliminary simulations for the design of the test set-up.