scholarly journals Effects of Soil-Structure Interaction on Torsionally Coupled Base Isolated Machine Foundation under Earthquake Load

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Karmegam Rajkumar ◽  
Ramanathan Ayothiraman ◽  
Vasant A. Matsagar
Keyword(s):  
Soil Structure ◽  
Natural Frequencies ◽  
Ground Motions ◽  
Soft Soil ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Machine Foundation ◽  
Earthquake Ground Motions ◽  
Torsional Coupling ◽  
Base Isolators

In this paper, the influence of soil-structure interaction (SSI) on a torsionally coupled turbo-generator (TG) machine foundation is studied under earthquake ground motions. The beneficial effects of base isolators in the TG foundation under earthquake ground motions are also studied duly, considering the effects of SSI. A typical TG foundation is analyzed using a three-dimensional finite element (FE) model. Two superstructure eccentricity ratios are considered to represent the torsional coupling. Soft soil properties are considered to study the effects of SSI. This research concludes that the effects of torsional coupling alter the natural frequencies, if ignored, could lead to unsafe design. The deck accelerations and displacements are increased with an increase in superstructure eccentricity. On the other hand, the deck accelerations and displacements are greatly reduced with the help of base isolators, thus confirming the beneficial use of base isolators in machine foundations to protect the sensitive equipment from the strong earthquake ground motions. However, the effects of SSI reduce the natural frequencies of the TG foundation resting on soft soil conditions and activate the higher mode participation, resulting in amplifying the response.

scholarly journals Evaluation of Soil-Structure Interaction on the Seismic Response of Liquid Storage Tanks under Earthquake Ground Motions

2016 ◽  
Author(s):  
Mostafa Farajian ◽  
Mohammad Iman Khodakarami ◽  
Denise-Penelope N. Kontoni
Keyword(s):  
Seismic Response ◽  
Soil Structure ◽  
Ground Motions ◽  
Time History ◽  
Soil Structure Interaction ◽  
Storage Tanks ◽  
Structure Interaction ◽  
Earthquake Ground Motions ◽  
Liquid Storage ◽  
Matlab Programming

Soil-structure interaction (SSI) could affect the seismic response of structures. Since liquid storage tanks are vital structures and must continue their operation under severe earthquakes, their seismic behavior should be studied. Accordingly, the seismic response of liquid storage tanks founded on half space soil is scrutinized under different earthquake ground motions. To better comparison, the six considered ground motions are classified based on their pulse like characteristics, into two groups, named far and near fault ground motions. To model the liquid storage tanks, the simplified mass-spring model is used and the liquid is modeled as two lumped masses known as sloshing and impulsive, and the interaction of fluid and structure is considered using two coupled springs and dashpots. The SSI effect, also, is considered using a coupled spring and dashpot. Besides, four types of soils are used to consider wide variety of soil properties. To this end, after deriving the equations of motion, the MATLAB programming is employed to obtain the time history responses. Results show that although the SSI effect leads to decrease the impulsive displacement, overturning moment and normalized base shear, the sloshing (or convective) displacement is not affected by such effects due to its long period.

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