عنوان مقاله [English]
In recent years, researchers have been intensively studied the dynamic response of liquid containers under ground excitation. However, most of the studies were conducted on cylindrical tanks while those concerning rectangular tanks are not adequate. In the early investigations, approximate methods were proposed to
include the effect of hydrodynamic pressure for a symmetric fluid container subjected to horizontal acceleration. The fluid response was represented by impulsive and convective components. The fluid was assumed to be incompressible and the container was assumed to have rigid walls. Recently, very strong earthquakes caused heavy damage to many liquid storage tanks. It was concluded that the assumption of a rigid wall may not be appropriate for the structural modeling. Including the wall deformability in a dynamic analysis requires a
systematic knowledge and understanding of the fluid-structure free-vibrational characteristics .
Modal test is one form of non-destructive testing that may be used to obtain information on the dynamic behavior of actual structures. This type of experimental study is conducted to determine different modal parameters of a structure such as natural frequencies, damping and mode shapes or to verify the theoretical models and predictions. This technique has the advantage of determining the real structural properties without using any assumption and taking into account the actual boundary condition.
In this paper, a numerical-experimental study of the overall dynamic response of rectangular concrete tanks is presented. In order to identify the natural frequencies that mainly contribute to the response, modal tests on a
rectangular concrete tank model for different liquid levels were carried out. Also, a numerical model that accounts for the interaction between fluid and structure was developed. A very good agreement between experimental and numerical results was obtained. In the numerical study, the influence of the sloshing on the natural frequencies and their modal pressure distribution are investigated. The results indicate that sloshing has a significant effect on the dynamic characteristics of the system; thus, in case where an accurate dynamical analysis is required, the sloshing should be considered.