Investigation of Seismic Behaviour of Underground R/C Water Reservoirs

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Investigation of Seismic Behaviour of Underground R/C Water Reservoirs

ارائه دهنده: Provider: Mohammad Navid Lachinov

اساتید راهنما: Supervisors: Mohammad Shushtari (Ph.D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: دکتر محمود نیلی - دکتر فریدون رضایی

زمان و تاریخ ارائه: Time and date of presentation: September, 17, 2020

مکان ارائه: Place of presentation:

چکیده: Abstract: Reservoirs are one of the important components of water supply systems that must be designed in such a way that in addition to compensating for changes in water demand, reducing water pressure fluctuations in the distribution network, storing and providing water needed for firefighting and water supply and maintenance during water supply and water supply. They may also prevent water pollution. Due to the development of cities and the increase in urban population, the use of underground or on the ground reservoirs for storing water, petroleum products or storing waste from industrial units has increased. The study of the seismic behavior of underground reservoirs is very important in terms of the distribution of dynamic fluid pressure inside the reservoir and the surrounding soil pressure due to earthquake loading. Although many numerical studies have been performed to better understand the behavior of concrete underground tanks, even the most comprehensive of them can not fully cover the interaction of variables participating in the performance of these structures. In addition, real-scale laboratory studies impose a lot of cost and time, which limits the number of parameters to be evaluated, so numerical simulation is a powerful tool for laboratory studies. In order to evaluate the performance of this method, in the present study, 4 samples of underground concrete tanks were modeled using SAP2000 software; In this study, quantitative assessment of structural vulnerability under the effects of gravity, lateral loads, fluid pressure, and soil pressure around the structure was investigated. Due to the rigid behavior of the foundation, in the structural model the foundation was applied as an equivalent spring. The models were analyzed based on Static and Response spectrum analysis in two series of samples, each of which was modeled with two types of compressive strengths of 25 and 35 MPa in two states, full and empty of water. For each sample, the stress and deformation of the foundation, roof and walls of the tanks were studied, modal analysis and also the force of the columns were investigated. The effect of the roof connection to the tank walls was also evaluated. Examining the modeled samples, it was found that the deformation and stresses in the foundation, ceiling and walls of the tanks in the full state of water are more than in the empty state of water. It was also further determined that the deformation and stresses of the full and empty state of concrete tanks with a compressive strength of 25 MPa are greater than the deformation and stresses of the full and empty states of concrete tanks with a compressive strength of 35 MPa. By examining Response spectrum analysis and comparing it with the results of Static analysis, it was found that Response spectrum analysis gives values of more than 17% compared to static analysis and the cross-sectional values of rebars are also higher. Also, by examining the modal analysis of reservoirs, it was found that the values of modal analysis increase with decreasing structural stiffness and the presence of fluid in the reservoir. Finally, by examining the effect of rigid connection of the roof and walls, the stresses and density of the rebars increased in the areas of wall-to-ceiling connection and corner areas in the walls and foundations. Key Words: Underground Reservoirs, Seismic behavior, Finite Element Method, Concrete Reservoirs

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