Seismic Response of Partially Filled Sloped Bottom Container and Tuned Liquid Damper for Vibration Control

Abstract

The oscillation of the unrestrained free liquid surface in a partially filled container due to some external excitation is termed as sloshing. It comprises a wide range of problems in many fields of engineering such as aerospace, civil, marine, nuclear and so on. In the field of civil engineering, a considerable understanding of sloshing behavior in a water retaining structure is needed. This dissertation makes an honest attempt to study the response of ground supported sloped bottom container and its application as a tuned liquid damper to control the uncalled vibration of the structure.
In this thesis, the finite element method in two dimensional space is adopted where the liquid domain is discretized as a combination of three node triangular and four node quadrilateral elements. A parametric study is carried out with different slope angle and bottom length on ground supported sloped bottom tanks. The numerical study is dedicated to investigate the liquid response in sloped bottom tanks under earthquake ground motion of various frequency contents. The model is efficient in determining both the impulsive and convective responses of liquid in container. The dynamic parameters of sloshing are manifested in terms of base shear force, slosh displacement and pressure distribution along the walls of the containers. It is observed that the geometry and size of the container plays a significant role in sloshing behavior of partially filled container. Also, the frequency content of earthquake ground motion is found to affect the sloshing characteristics significantly.
Further, the study is extended to investigate the effectiveness of sloped bottom TLD in controlling the vibration of structure. A TLD-structure interaction model is developed for the shear building structures subjected to horizontal harmonic and earthquake ground motions. A parametric study is carried out to determine the performance of sloped bottom TLD in reducing the undesired vibration of the structure. The experimental investigation is undertaken in a TLD-structure model, on a unidirectional shake table capable of producing horizontal harmonic excitation. The efficiency of different angle sloped bottom TLD and flat bottom TLD in mitigating the structural vibration is determined. Studies reveal that sloped bottom TLD efficiently controlled the unwanted vibration of structure with less amount of water than that of rectangular TLD.
Lastly, Adaptive Neuro Fuzzy Inference System (ANFIS), a smart hybrid soft computing technique is implemented to predict the dynamic properties of sloshing, so that the expenditure associated with experiments can be reduced. The numerically simulated results are used as input-output data set. ANFIS is found to be a promising soft computing tool in predicting the earthquake magnitude and sloshing response in sloped bottom containers. Subtractive clustering algorithm is found efficient to predict the earthquake magnitude and hydrodynamic base shear force in very small amount of time.