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چكيده انگليسي :

Development of fragility curves for concrete cylindrical storage tanks Mohammad Yazdabad Mohamad yazdabad@gmail com Date of Submission March 11 2013 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Dr Farhad Behnamfar farhad@cc iut ac ir AbstractOne of the necessary structures in industrial installation and water supply system are tanks Because ofdifferent purposes tanks are built as on ground elevated buried or half buried Tanks are used for storageof different materials such as water oil nitrogen high pressure gases and chemical materials Mostly tanksare in two shapes of rectangular and circular For water storage usually concrete tanks are used These tanksare utilized for various purposes such as storage providing pressure and calming fluid flow Damage inthese tanks can cause financial and vital injuries Also the necessity of providing water for a regionstricken by an earthquake represents the importance of investigating their seismic performance forassessing their safe behavior Because of widespread use of tanks and their vulnerability in earthquakes notable damages have been observed during previous earthquakes Sometimes these damages cause a fullloss of tank performance and the fluid stored in it and the other time it causes only repairable faults In thisresearch the dynamic behavior of concrete cylindrical tanks is investigated Effective parameters indynamic response of tanks such as wall rigidity base fixity vertical acceleration of ground motion andheight to diameter ratio are evaluated Also for studying vulnerability of these tanks seismic fragilitycurves for three different tanks with height to diameter ratios of 0 75 0 5 and 0 25 are developed Moreover the effect of fill percentage on seismic fragility curves are investigated with considering threedifferent cases for one of the tanks The tanks are designed based on ACI 350 3 and evaluated by dynamicanalysis of with Abaqus It is assumed that the tanks rest on a rigid foundation One of the most importantissues in designing concrete tanks is control of crack width for preventing leakage and corrosion of rebars In addition knowledge of water wave height due to sloshing of water is important for considering the freeboard Seismic fragility curves for critical crack width bending capacity of wall and water over flow fromtanks wall are developed One other important problem about dynamic behavior of circular concrete tanksthat has less been investigated in previous researches is the simultaneous effect of vertical and horizontalcomponents of earthquake acceleration The results of numerical analysis show that increase of wallflexibility has a considerable effect on the response of fluid and especially tank wall Also use of a hingedbase connection instead of a fixed base connection significantly reduces the maximum bending moment inthe tanks wall It is observed that the effect of vertical acceleration of earthquake should be taken intoaccount in designing tall tanks The seismic fragility curves for critical crack width and fluid spillover intanks represented that the height to diameter ratio and the fill percentage are major sources of uncertainty inseismic fragility curves of cylindrical concrete water tanks Key WordsConcrete cylindrical tank Dynamic analysis Flexural crack width Water sloshing Seismic fragility curve

يزدآباد، محمد

ارائه منحني هاي آسيب پذيري لرزه اي براي مخازن بتني استوانه اي آب

تحليل ديناميكي , عرض ترك خمشي , تلاطم آب