Abstract:The numerical investigation on the seismic response of RC elevated liquid storage tanks installed with viscous dampers is presented. A discrete two-mass model for the liquid and multi-degree of freedom system for staging, installed with the dampers are developed for Reinforced Concrete (RC) elevated liquid storage tanks. The elevated tank is assessed for seismic response reduction when provided with Linear Viscous Damper (LVD) and Nonlinear Viscous Damper (NLVD), installed in the staging. The RC elevated liqui… Show more
“…The choice of proper i th and j th modes is crucial, i.e., the specified modes should significantly contribute to the structures’ response 35 . Figure 10 Rayleigh damping 40 . …”
Section: Methodsmentioning
confidence: 99%
“…As suggested by EC-8, the damping ratios of 0.5 and 5 percent are assigned for the convective and impulsive components, respectively. Furthermore, the stiffness proportional damping equivalent to 5 percent of critical damping is assumed as structural damping 40 .…”
Elevated water tanks are considered crucial infrastructure due to their significant role in supporting essential services. A strong ground motion may result in a failure or significant damage to a reinforced concrete shaft of an elevated water tank because hysteric energy dissipation is limited to the formation of plastic hinges at the base of the shaft, while the nonlinear properties of the rest of the shaft remain underutilised. The innovative system of assembling RC shafts for elevated water tanks using a slit wall technique was developed to enhance energy dissipation along with the shaft height by introducing slit zones. The comparative nonlinear dynamic analysis between three-dimensional models of elevated water tanks with different shaft diameters and heights was conducted using SAP2000 software. The results of elevated water tanks with slit and solid reinforced concrete shafts were compared. The research findings showed that during a seismic event, the slit zones increased the ductility of the shaft, reduced stress concentration in the lower part of the shaft, and provided uniform stress distribution throughout the shaft's height. The effect of the innovative system is especially noticeable in the elevated water tanks with tall and slender shafts.
“…The choice of proper i th and j th modes is crucial, i.e., the specified modes should significantly contribute to the structures’ response 35 . Figure 10 Rayleigh damping 40 . …”
Section: Methodsmentioning
confidence: 99%
“…As suggested by EC-8, the damping ratios of 0.5 and 5 percent are assigned for the convective and impulsive components, respectively. Furthermore, the stiffness proportional damping equivalent to 5 percent of critical damping is assumed as structural damping 40 .…”
Elevated water tanks are considered crucial infrastructure due to their significant role in supporting essential services. A strong ground motion may result in a failure or significant damage to a reinforced concrete shaft of an elevated water tank because hysteric energy dissipation is limited to the formation of plastic hinges at the base of the shaft, while the nonlinear properties of the rest of the shaft remain underutilised. The innovative system of assembling RC shafts for elevated water tanks using a slit wall technique was developed to enhance energy dissipation along with the shaft height by introducing slit zones. The comparative nonlinear dynamic analysis between three-dimensional models of elevated water tanks with different shaft diameters and heights was conducted using SAP2000 software. The results of elevated water tanks with slit and solid reinforced concrete shafts were compared. The research findings showed that during a seismic event, the slit zones increased the ductility of the shaft, reduced stress concentration in the lower part of the shaft, and provided uniform stress distribution throughout the shaft's height. The effect of the innovative system is especially noticeable in the elevated water tanks with tall and slender shafts.
“…Their failure mechanism is influenced by a multitude of factors, including the tank's construction material, tank configuration, tank type, and supporting mechanism [1]. Several researchers and practitioner engineers have focused their efforts on assessing the seismic vulnerability of such structures [2].…”
Failure of a tank during an earthquake can result in significant financial, human, and environmental losses. Thus, their lack of resiliency against strong earthquakes may result in refinery disruption. This has the potential to have a considerable impact on any economic system. As a result, more research into the seismic performance of tank structures is required to attain the highest possible level of resistance against strong earthquakes. In this paper, we aim to look into the installation of seismic isolation systems in cylindrical steel storage tanks. A nonlinear 3D finite element model is developed with ANSYS software. Moreover, tank wall material nonlinearity, fluid-structure-interaction, and sloshing components are considered. The bilinear hysteretic LRB is used for modal and time-history analysis. In this work, three tanks with varying aspect ratios are studied: "Model A", "Model B", and "Model C". Furthermore, the fixed tank's fundamental frequencies were compared to the analytical results of the American API 650 Standard. Subsequently, the dynamic behavior response of the researched tanks to the horizontal component of the El-Centro 1940 earthquake with PGAs of 0.34g and 0.5g is investigated. As a result, the dominating frequency of the seismic isolation system is within the effective frequency range of seismically isolated systems. The results illustrate that the base isolation limits the tank wall movement with a large displacement in the isolators; the mode shape is a cantilever beam in all isolated circumstances. The total seismic response reduction in the slender tanks is greater as compared to the broad case in the base-isolated tanks. The sloshing displacement increases with an increase in the tank aspect ratio. Additionally, the isolation device eliminates tank buckling at the base and top of the tank shell during seismic excitation (elephant foot and diamond buckling). It can be concluded that the seismic isolation technique has a more significant impact on reducing the dynamic response of ground-supported tanks, particularly in taller tanks as compared to broad tanks. Doi: 10.28991/CEJ-2022-08-06-013 Full Text: PDF
“…Waghmare et al [8] considered a numerical investigation in a multi-real earthquake for reinforced concrete elevated tanks in viscous dampers. They found that viscous dampers' nonlinearity and low damping constant contributed a comparable reduction to those viscous dampers with linear and high damping constant.…”
This paper aims to illuminate the influence of hydrodynamic pressure generated in a water storage tank on the behavior of saturated sand that its support. Experimental tests were performed on two cylindrical water tank models using a fabricated shaking table which consists of a flexible laminar shear box. The first model is a water storage tank partially full of water, and the second one is a tank model with an equivalent load of water pressure to simulate the water storage tank without hydrodynamic pressure. Three earthquake histories (Kobe, El-Centro, and Ali Al Gharbi) were implemented on models to study a varied range of acceleration. It was found that the settlement and lateral displacement directions in the water storage tank were significantly increased compared to the equivalent load resulted in the second model in all cases of the acceleration histories. Also, it was monitored the pore water pressure during the testing period, and it was noticed that the excess pore pressures were affected by the hydrodynamic pressure and increased compared to the results recorded at the condition of no hydrodynamic pressure.
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