Boden-Bauwerk-Fluid-Interaktion flüssigkeitsgefüllter Tankbauwerke auf nachgiebigen, vielfach geschichteten Böden unter seismischer Einwirkung

  • Soil-structure-fluid-interaction of liquid-filled tanks on compliant mulit-layered soils under earthquake action

Michel, Philipp; Klinkel, Sven (Thesis advisor); Könke, Carsten (Thesis advisor); Butenweg, Christoph (Thesis advisor)

Aachen : Rheinisch-Westfälische Technische Hochschule Aachen, Fakultät für Bauingenieurwesen, Lehrstuhl für Baustatik und Baudynamik (2021)
Book, Dissertation / PhD Thesis

In: Schriftenreihe des Lehrstuhls für Baustatik und Baudynamik der RWTH Aachen University 11
Page(s)/Article-Nr.: 1 Online-Ressource : Illustrationen

Dissertation, RWTH Aachen University, 2021

Abstract

The aim of this thesis is the seismic analysis of the soil-structure-fluid interaction (SSFI) of liquid-filled tank structures, based on compliant, multi-layered soils. The fluid movement in case of an earthquake is divided into a convective sloshing movement and a common impulsive bending vibration of fluid and tank shell. Following the fluid movement, dynamic fluid pressures are generated. These result in the stress distribution in the tank shell, which is used to design the structure. The support of the structure on compliant soils has a significant influence on the overall dynamics of the tank shell. A powerful model is required to represent all dynamic interaction effects together and to calculate stress distributions in case of earthquakes. An engineering model for the targeted and effective holistic calculations of SSFI is presented. Dynamic fluid pressures and stress distributions in the tank shell are calculated using a practical one-step procedure. In terms of the substructure method, the overall model is divided into a soil model and a structure-fluid system. These are first considered individually and coupled for final analysis. The routine SSI-SALT uses the Precise-Stiffness-Matrix-Method as soil model and the Added-Mass-Method for the simulation of the tank shell in order to represent the SSFI effects as accurately as possible, but to remain applicable in practice-oriented investigations. The tank shell is coupled with the impedance functions of the foundation-base system. Normative response spectra as well as earthquake spectra amplified according to the soil structuring are used to affect the tank shell. The stress curves due to earthquake action can be calculated for the entire system without any further intermediate steps. Compared to rigid support, compliant soils allow a greater rigid body rotation of the foundation and tank shell. Accordingly, the shell is less strongly deformed, which results in a lower impulsive pressure.Stronger excitation inevitably leads to greater fluid pressures. The actual dynamic pressure therefore follows from the combination of storage condition and action. The influence of the SSFI is transferred from the pressures to the stress distribution. The tank parameters slenderness and ratio of wall thickness to tank radius are identified as the decisive influencing variables on the overall dynamics. From the tank radius follows the radius of the foundation, which, together with the ground stratification, has the leading influence on the impedance. Like the ground movement, this is dominated by the shear modulus and the thickness of the ground layers. The complex interaction between the individual variables does not allow a general estimate of the stress distribution for tanks on compliant soils. Rather, a SSFI analysis must be carried out for each location and tank, which is possible with SSI-SALT at reasonable cost.

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