Seismische Auslegung von Tankbauwerken

In the present work the nonlinear interaction effects of coupled tank liquid system subjected to seismic excitation are investigated. Therefore, a numerical model representing the fluid-structure interaction is developed and used in a transient analysis to enable a more accurate calculation of the seismic response of liquid filled tank structures. With this type of fluid-structure interaction analysis the existing semi-analytical calculation concepts are studied with regard to the validity of their underlying simplifications and improved. Furthermore, strategies are developed for the combination of the different hydrodynamic pressure components calculated with the simplified procedures for a multidimensional seismic excitation.Since the semi-analytical concepts are valid only for a rigid support at the bottom of the tank where the seismic excitation acts directly on the bottom, the simplified calculation procedures are not transferable to different types of boundary conditions. Therefore, in the second part of the work the fluid-structure interaction analysis is used to investigate base isolated tank structures. Based on the results of the fluid-structure interaction calculations a simplified, general calculation approach is developed for analyzing seismically isolated tanks. This approach takes into account the nonlinear properties of conventional base isolation systems and thus allows to determinate the modified hydrodynamic forces acting on the shell of the tank as well as the resulting stress distribution in the shell.In the third part of the work, two numerical concepts for the verification of stability are investigated. These concepts are based on static analyses of the global tank shell subjected to the entire load spectrum. The combined load due to seismic excitation and thus mutual interactions of the several stress components occurring simultaneously may have both positive and negative influence with regard to the buckling resistance, which can be considered. The first numerical concept is based on a fully nonlinear analysis of the imperfect shell. Here, consistent geometric imperfections according to the concept of quasi-collapse affine imperfections as well as eigenmode affine equivalent imperfections are examined with regard to their buckling load reducing effect. Due to the consideration of material and geometrical nonlinearity, a maximum load factor of the tank can be achieved. The second calculation concept includes a simplified verification process that has not been applied to seismically loaded tank structures so far. For critical details in those concepts recommendations are elaborated. The recommendations are verified by fluid-structure interaction analyses. As a result, a guideline for the proof of stability of shells under combined loads is given