Search

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 liquid storage tanks are analyzed for two levels of liquid containment in the tank, 100% and 25% of the tank capacity. Three Configurations of placements of dampers viz. dampers at alternate levels (Configuration I and Configuration II) and dampers at all the panels of the staging of the tank (Configuration III) are considered. To study the effect of peak ground acceleration, eight real earthquake time histories with accelerations varying from 0.1 g to 0.93 g are considered. The nonlinearity in the viscous damper is modified by taking force proportional to various velocity exponents. It is found that the nonlinear viscous dampers with lower damping constant result in a comparable reduction in the response of RC elevated liquid storage tank, to that of linear viscous dampers with higher damping constant. A lower damping constant signifies compact the size of the damper. Doi: 10.28991/cej-2020-SP(EMCE)-09 Full Text: PDF

In the field of fatigue crack, crack size is a worthy topic to discuss. The relationship between crack length and depth is studied based on the Paris law, and a numerical model is established. The validity of the model is proved by comparing theoretical data with experimental data. In addition, the analysis of stress distribution of liquid-storage tank is carried out and the influence of hoop stress on the liquid-storage tank is considered. Remaining life of the tank is predicted through the numerical model. The feasibility of the numerical method is verified by predicting the remaining life of the tank, which provides a simple way for fatigue life prediction of the liquid-storage tank.

Despite the proven effectiveness of tuned liquid dampers (TLDs), readily available liquid storage tanks are rarely utilized for vibration control of laterally-excited structures, as these are deep tanks with low inherent damping. Further, the fluctuation in liquid level in these tanks also causes variation in the fundamental sloshing frequency, leading to detuning. To overcome these problems, a novel TLD with floating base (TLD-FB) is proposed, in which a constant and shallow liquid level is maintained between the free liquid surface and the floating base. The liquid above the floating base acts as a conventional shallow TLD that always remains tuned to the structural frequency. The paper demonstrates how the TLD-FB can be incorporated into a water storage tank system on an example building without disturbing its functionality and achieves structural response reduction, despite water level fluctuations in the tanks.

The present study proposes the use of base isolation for liquid containers and its effectiveness is investigated numerically. The seismic response of partially filled ground-supported recta...

Oil storage tanks play a very important role in economic and social development; however, there are numerous cases of damage caused by wind and earthquake. Considering fluid-structure interaction, wind interference and material nonlinearity, firstly, wind fields are S^#simulated by computational fluid dynamics and solved by SIMPLEC method under the conditions of single tank and double tanks; second, the wind pressures in the two cases are obtained and applied to the oil storage tanks, 3-D numerical calculation model is established. Wind disturbance effect on dynamic responses is discussed, and influence of storage ratio and seismic wave type on dynamic responses under wind-earthquake action is further investigated. Results show that wind disturbance effect has a great influence on the dynamic responses of liquid storage tank, especially in the empty state. When the liquid storage ratio is large, traditional oil storage tank is easy to be damaged under the action of wind-strong earthquake. Wind interference effect should be considered in the design and application of oil storage tanks, at the same time, shock absorption and strengthening measures should be taken for oil storage tanks under wind-strong earthquake.

Liquid-containing storage tanks are important structures in industrial complexes. Because earthquake damages to liquid storage tanks can cause structural collapse, fires, and hazardous material leaks, there have been continuous efforts to mitigate earthquake damages using seismic fragility analysis. In this regard, this study focuses on the seismic responses and fragility of liquid storage tanks. First, the characteristics of earthquake ground motions are a critical factor influencing the seismic fragility of structures; thus, this study employs real earthquake records observed in the target area, southeastern Korea, with the earthquake characteristics estimated based on the ratio of peak ground acceleration to peak ground velocity. When a liquid storage tank oscillates during an earthquake, additional forces can impact the tank wall owing to hydrodynamic pressures. Therefore, this study presents a sophisticated finite element (FE) model that reflects the hydrodynamic effect of an oscillating liquid. Another advantage of such an FE model is that detailed structural responses of the entire wall shells can be estimated; this is not possible in simplified lumped mass or surrogate models. Lastly, probabilistic seismic demand models are derived for three critical limit states: elastic buckling, elephant’s foot buckling, and steel yielding. Using the real earthquake ground motion records, constructed FE model, and limit states, a seismic fragility analysis is performed for a typical anchored steel liquid storage tank in Korea. In addition, for comparison purposes, a ring-stiffened model is investigated to derive a seismic fragility curve. The results of the seismic fragility assessment show that elastic buckling is the most vulnerable damage state. In contrast, elephant’s foot buckling and steel yielding indicate relatively severe damage levels. Furthermore, it is observed that ring stiffeners decrease the elastic buckling damage, although there is no practical effect on elephant’s foot buckling and steel yielding in all ground motion intensities.

The current study proposes a new vertical seismic isolation of an aboveground liquid storage tank (AST) and theoretically and numerically evaluates its effectiveness for a comprehensive practical range of tank geometries. In the proposed system, the forces in the vertical direction caused by the overturning moment are isolated as an alternative to the common horizontal system used for shear base isolation of ASTs. The equations of motion for a liquid tank equipped in the proposed system were extracted using the mass-spring simplified model of contained liquid. A parametric study was performed by employing the non-linear solution of the governing equations and the effectiveness of the proposed system for all AST aspect ratios is discussed. The numerical results show that the overturning moment of the tanks equipped with the proposed isolation system decreased significantly with respect to the corresponding fully anchored tanks. The results of the parametric study on the tank aspect ratio and liquid height indicate that the proposed system is more efficient for slender tanks than for broad tanks.

In this paper, the relation between the steel cylindrical tank geometry and the governing critical damage mode of the tank shell is numerically determined for all practical ranges of liquid storage tanks (aspect ratio H/D = 0.2 to 2). In addition, the interaction between the seismic intensity, soil type, acceptable seismic risk and tank geometry along with the extra material demanded by the seismic loads is examined based on the provisions of major codes. The importance of seismic factors on the economics of the design of a liquid tank in zones with high seismic activity is comprehensively discussed. In this regard, an empirical relation to estimate the steel volume required for specific seismic conditions and tank geometries is proposed based on the results of analysis.

Steel cylindrical tanks are widely used for the storage of hazardous substances of which leakage must be prevented under any circumstances. However, the dynamic response of the steel cylindrical liquid storage tank depends sensitively on the fluid–structure interaction and the vibration of the tank structure and necessitates clarification for the safety of the tank structure. This paper presents the results of shaking table tests performed to examine the dynamic behavior of a scaled cylindrical steel tank model considering the presence or not of fixed roof and added mass at the top of the tank for various fluid levels. The test results confirm the occurrence of both beam-type and oval-type vibration modes and show that the larger content of liquid inside the container amplified the acceleration along the height of the cylindrical tank. The oval-type vibration modes are seen to be more dominant in case of large water-to-structure mass ratio.

Ground-supported unanchored liquid-storage cylindrical tanks, when subjected to strong seismic loading may exhibit uplifting of their bottom plate, which may have significant effects on their dynamic behavior and structural integrity. In particular, due to uplifting, a substantial amount of plastic deformation develops at the vicinity of the welded connection between the tank shell and the bottom plate that may cause failure of the welded connection due to fracture or fatigue, associated with loss of tank containment. The present study focuses on the base uplifting mechanism and tank performance with respect to the shell/plate welded connection through a numerical simple and efficient methodology that employs primarily a simplified modeling of the tank as a spring-mass system for dynamic analysis, enhanced by a nonlinear spring at its base to account for the effects of uplifting, supported by a detailed finite element model of the tank for incremental static analysis. The latter model is capable of describing with accuracy the state of stress and deformation at different levels of lateral loading, in order to obtain the overturning moment-rocking angle relationship to be used in the simplified model. The methodology is applied in two cylindrical liquid storage tanks of different aspect ratios focusing on local performance of the welded connection, towards assessing the strength of the welded connection. The numerical results provide better understanding of tank uplifting mechanics and strength against failure of the welded connection at the tank bottom. Furthermore, the proposed methodology can be used for efficient assessment of uplifting effects on tank structural safety, towards minimizing seismic risk in industrial facilities.

The inappropriate performance of liquid storage tanks following devastating earthquakes indicates that the tank damage could lead to catastrophic consequences. As the rocking response of unanchored tanks plays a significant role in their seismic performances, the base anchorage is an essential element to control the seismic performance of on-ground tanks. The present study focuses on the effect of anchorage systems, as the retrofitting strategy, on the seismic performance of an existing unanchored tank damaged during the Silakhor Earthquake of 2006 in Iran. To this end, regular steel and shape memory alloy (SMA) anchor bolts were utilized. The Seismic performance of the tank was evaluated before and after retrofitting. For every retrofitted tank, different configurations of anchor bolts were considered. The seismic performance of tanks has been investigated using incremental dynamic analysis (IDA) analysis. To assess the seismic performance of every case, a fragility analysis was conducted. The results revealed that anchored tanks showed better seismic performance compared to unanchored ones. It was also shown that the combination of energy dissipation and the super-elastic behavior of SMA anchors leads to a considerable reduction in shell failure and damage to the anchorage system.

Summary This paper proposes a dynamic centrifuge model test method for the accurate simulation of the behaviours of a liquid storage tank with different types of foundations during earthquakes. The method can be used to determine the actual stress conditions of a prototype storage-tank structure. It was used in the present study to investigate the soil-foundation-structure interactions of a simplified storage tank under two different earthquake motions, which were simulated using a shaking table installed in a centrifuge basket. Three different types of foundations were considered, namely, a shallow foundation, a slab on the surface of the ground connected to piles and a slab with disconnected piles. The test results were organised to compare the ground surface and foundation motions, the slab of foundation and top of structure motions and the horizontal and vertical motions of the slab, respectively. These were used to establish the complex dynamic behaviours of tank models with different foundations. The effects of soil–foundation–structure interaction with three foundation conditions and two different earthquake motions are focused and some important factors, that should be considered for future designs are also discussed in this research. Copyright © 2017 John Wiley & Sons, Ltd.

Large capacity tanks storing various liquids are important components in distribution and transmission systems. During operation tanks can be subjected to different types of loading. Therefore, maximum attention must be paid to the tank design to capture all possible causes and forms of failures. The article deals with the procedure for seismic resistance of liquid storage tanks which are in accordance with the principles of Eurocode 8 standard. The seismic analysis is performed on flexible (steel) circular vertical ground-supported model of tank containing liquid (water). The main aim is to determine basic seismic characteristics, distributions of hydrodynamic pressure, dynamic properties and response of investigated tank-liquid system subjected to earthquake excitation (El Centro). Seismic analysis and results comparison are carried out on mechanical spring-mass model (Eurocode 8) and finite element model (ANSYS).

Granular piles/stone columns are one of the most commonly preferred ground engineering systems for improving a variety of weak soils, such as soft clays, loose sands, waste fills, and ash ponds. They are installed using a range of techniques, namely vibro compaction, vibro replacement, composer method, rammed stone columns, and geopiers, based on on-site conditions and availability of machinery. Granular piles improve the ground by densification especially in loose sands, by reinforcement in case of waste fills and ash ponds, by reinforcement and consolidation in case of soft clays, and mitigate damages from liquefaction by functioning as drains. The paper presents a critical review of developments related to granular piles encompassing recent analytical, experimental, numerical studies, and field investigations of their compressive, uplift, and seismic responses. Three well-documented case histories of an embankment, a mechanically stabilized earth wall, and a liquid storage tank on granular pile-enginee...

Dynamic analysis of circular vertical ground supported liquid storage tank is one of the complicated problem in the earthquake engineering. The paper deals with the dynamic analysis of fluid effect on the circular tank with considering of constant wall height and constant fluid filling height by variable tank width. The analytical model of the tank with liquid used in Eurocode 8 was used for parametric study.Dynamic analysis of circular vertical ground supported liquid storage tank is one of the complicated problem in the earthquake engineering. The paper deals with the dynamic analysis of fluid effect on the circular tank with considering of constant wall height and constant fluid filling height by variable tank width. The analytical model of the tank with liquid used in Eurocode 8 was used for parametric study.

Previous investigations have demonstrated that strong earthquakes can cause severe damage or collapse of storage tanks. Theoretical studies by other researchers have shown that using energy-dissipating anchors can reduce the axial compressive stresses in the tank shell compared to the fully anchored case. Those studies have also shown that using energy-dissipating anchors can reduce the displacement of the tank compared to the unanchored case. However, there is no experimental work to validate the results obtained from these numerical studies. This paper reports on a series of experiments using a shake table on a scale model PVC tank containing water. A comparison of the seismic behaviour of a fully fixed base system (tank with anchorage), a system free to uplift (tank without anchorage) and a partially fixed system (tank with slip-friction connectors) is presented. The slip-friction connectors are calibrated by performing cyclic tests. The experiments were performed using recorded ground motion scaled to the New Zealand design spectra for two Wellington sites. Measurements were made of the axial compressive stresses in the tank shell and the horizontal displacement of the top of the tank. The experiments showed the beneficial effects of using slip-friction connectors in storage tanks, reducing the uplift displacement in comparison with an unanchored tank and reducing the axial stresses compared to a fully fixed tank. A numerical model is proposed which corroborates these results.

ONTARE. REVISTA DE INVESTIGACIÓN DE LA FACULTAD DE INGENIERÍA Este artículo presenta la formalización matemática de las redes de Petri híbridas y coloreadas para el anidamiento Latente de Fallos (AL), como método de abstracción respecto al diagnóstico de fallos llamado Redes de Petri Híbridas y Coloreadas para el Diagnóstico de Fallos (RdPHCDF). Además de esto, se demuestra la mayor capacidad de síntesis y modelado en el aislamiento y diagnóstico de fallos en sistemas complejos. Por otra parte, este trabajo presenta un ejemplo práctico de aplicación del método que consiste en un tanque de almacenamiento de líquidos.

The main topic of the paper is dimensioning steel liquid storage tank, rectangular in shape, with three compartments. Depending on the investor's request (dimensions required for the tank and maximum use of space) a need arose for structure with atypical shape. Austenitic stainless steel is used in this example what is recommended for use in aggressive environments. Dimensioning of steel plates, stiffened and unstiffened, according to Eurocode is carried out according to EN 1993-1-7, which refers to plates loaded out of their plane. Within the first part of the analysis dimensioning is performed according to Eurocode 3. The second part of the paper represents comparative analysis of results obtained according to Eurocode and results obtained using previous domestic standard SRPS.MZ.3. 054. (1981).

Summary A horizontal water storage tank was analyzed for seismic shaking at the 5 th level of the ITER Tokamak Complex in France. The objectives were to: (a) estimate the seismic forces in the tank; (b) calculate the sloshing response of the tank; (c) determine if baffles are needed to control sloshing; and (d) evaluate the possibility of using a single fixed support in the longitudinal direction to allow free thermal expansion of the tank. Approximate conservative analysis predicted very high sloshing wave and seismic forces in the tank. Fluid-structure interaction of the tank showed that only about 28% of the liquid moves with the tank wall and generates seismic forces in the longitudinal direction. The remaining 72% of the liquid sloshes near the free-surface and does not generate significant seismic forces. The sloshing wave is not high enough in the longitudinal direction because the fundamental sloshing mode is not excited due to its very low natural frequency. Hence baffles are not needed to control sloshing. The seismic force was low enough that a single fixed support can resist the entire seismic force in the longitudinal direction.

Ground-supported cylindrical tanks are used to store a variety of liquids. The fluid was develops a hydrodynamic pressures on walls and bottom of the tank during earthquake. This paper provides dynamic time-history response of concrete open top cylindrical liquid storage tank considering fluid-structure interaction due to earthquake. Numerical model of cylindrical tank was performed by application of the Finite Element Method (FEM) utilizing software ADINA. Arbitrary-Lagrangian-Eulerian (ALE) formulation was used for the problem analysis. Two way Fluid-Structure Interaction (FSI) techniques were used for the simulation of the interaction between the structure and the fluid at the common boundary

The isolation storage tank with 20000m3 responded to seismic is calculated by using the finite element analysis (FEA) program ANSYS, and horizontal displacement harmonic excitation is considered for investigation of the relative displacement of tank wall, liquid sloshing wave height, and the stress of tank wall. The analysis show that, with isolation, the maximal relative displacement, the maximal liquid sloshing wave height, and the maximal stress of tank wall are reduced obviously compared with tank that without isolation, and as site become soft, the maximal relative displacement of the tank wall at the top and the maximal wave height increase gradually, but the maximal stress of tank wall change little.

Sloshing is a violent resonant fluid motion in a moving tank. When a fluid moves and interacts with its container, the dynamic pressures of such an interaction may cause large deformation in the container wall as well as the supporting structure. Most of the work has been done on rectangular tanks. Moreover in most of the studies numerical approach is used. The present study is focused on the fluid structure interactions in an elliptical tank. The movement of fluid in an elliptical tank has been studied using simulation and experimentation and different baffle configurations are used. The pressure exerted by the fluid on the walls of tank is calculated over a certain period of time. The dynamic response of baffled liquid storage tank has been studied extensively to study the influence of location and shapes of baffles under excitation. Different baffle configurations were examined and role of combination of horizontal and vertical baffles were found to be significant in controlling the sloshing.

Seismic response of ground supported baseisolated liquid storage tanks are evaluated under bi-directional earthquakes. The base-isolated liquid storage tanks are modeled using mechanical analogs with two and three lumped masses (Model 1 and Model 2). Two types of isolation systems, such as sliding system and elastomeric system, are considered for the present study. The isolation systems are modeled using Wen’s equation for hysteretic isolation systems. Response of base-isolated liquid storage tanks, evaluated through two different modeling approaches, is compared. Both the models predict similar sloshing displacement. The effect of interaction between the mutually perpendicular seismic responses of the isolator is investigated for both the models. It is observed that interaction affects the peak seismic response of the base-isolated liquid storage tanks significantly, under the bi-directional earthquake components.

Previous investigations have demonstrated that strong earthquakes can cause severe damage or collapse to storage tanks. Theoretical studies by other researchers have shown that allowing the tank to uplift generally reduces the base shear and the base moment. This paper provides the necessary experimental confirmation of some of the numerical finding by other researchers. This paper reports on a series of experiments of a model tank containing water using a shake table. A comparison of the seismic behaviour of a fixed base system (tank with anchorage) and a system free to uplift (tank without anchorage) is con- sidered. The six ground motions are scaled to the design spectrum provided by New Zealand Standard 1170.5 (2004) and a range of aspect ratios (height/radius) is considered. Measurements were made of the impulsive acceleration, the horizontal displacement of the top of the tank and uplift of the base plate. A preliminary comparison between the experimental results and the recommendations provided by the liquid storage tank design recommendations of the New Zealand Society for Earthquake Engineering is included. The measurement of anchorage forces required to avoid uplift under varying conditions will be discussed.

Earthquake response of slender and broad liquid storage steel tanks isolated with variable curvature friction pendulum systems (VCFPSs) is investigated under near-fault motions. The tanks isolated with VCFPS are idealised with three-degrees-of-freedom associated with convective, impulsive and rigid masses. The frictional forces mobilised at the interface of the VCFPS are assumed to be velocity independent. The governing equations of motion of isolated tank are derived and solved in the incremental form using Newmark's method. For comparative study, the seismic response of liquid storage tanks with the VCFPSs is compared with that of same liquid storage tanks isolated using the friction pendulum systems (FPSs). The seismic response of isolated liquid storage tanks is also compared with that of the non-isolated tanks. Further, a parametric study is carried out to critically examine the behaviour of liquid storage tanks isolated with the VCFPSs. The important parameters considered are the friction coefficient of VCFPS, the fundamental period at the centre of the sliding surface of VCFPS and the tank aspect ratio. It is observed that under near-fault ground motions, the VCFPS is quite effective in controlling the seismic response, viz. the base shear, the sloshing displacement and the impulsive displacement, of liquid storage tanks.

The 2005 Buncefield vapour cloud explosion showed the huge cost associated with blast damage to commercial property surrounding a major explosion incident. In most cases there was serious disruption to business activity; in many cases the buildings had to be demolished or abandoned for long periods until extensive repairs were carried out. Another key feature of this and other recent vapour cloud explosions has been the damage done to storage tanks. The blasts almost invariably cause immediate top and bund fires in any tanks surrounded by the vapour – even if they contain relatively high flashpoint materials such as diesel. The first part of this paper describes the patterns of damage observed in buildings in the industrial estates around Buncefield. Methods for assessing the degree of external and internal damage are presented. The second part of the paper deals with failure modes and ignition of various types of liquid storage tank during vapour cloud explosions. Again, the Buncefield data provides excellent examples that illustrate the importance of tank design, fill level, location relative to the cloud, etc.

Steel cylindrical tank is one of the most common forms of liquid storage vessels. In this study the Imperialist Competitive Algorithm (ICA) is used to find the optimum size of a ground based cylindrical liquid storage tank that is supported at both ends and the design considerations are stability and strength constraints. In this study total internal pressure and total special pressure are assumed as two types of load. The optimization procedure is formulated with the objective to minimize the mass of the tank due to the allowable capacity of cylindrical tank.

To large liquid storage tank, based on the potential flow theory, considering fluid-structure interaction, the potential-based elements and the shell elements are used to simulate the liquid and the tank, respectively. Using the displacement-velocity potential finite element method formulas, the seismic response analysis method of the liquid storage tank is obtained, and is implemented based on the ADINA program. Some useful conclusions of the tanks under the earthquake loadings are obtained through two examples, which provide the reference for the seismic design theory and the seismic performance, and provide the analysis approach for the damage behavior and loss assessment of liquid storage tank.

The dynamic behavior of a liquid storage tank as a special structure differs from that of general structures. Important structures of cylindrical shape are used to store vital products, such as water and petroleum products, for cities and industrial facilities. Damage to these structures during a strong ground motion may lead to fire or other hazardous events. Liquid storage tanks are lifeline structures and strategically very important, since they have vital use in industries and nuclear power plants. In this research, an example reinforced concrete (RC) elevated water tank, with 900 cubic meters capacity, is studied under three pairs of earthquake records and analyzed in time history by using mechanical and finite element modeling techniques. The liquid mass of the tank is modeled as lumped masses known as sloshing mass, impulsive mass and rigid mass. The corresponding stiffness constants associated with these lumped masses are worked out depending upon the properties of the tank wall and liquid mass. Tank responses including base shear, overturning moment, tank displacement, and sloshing displacement under these three pairs of earthquake records are calculated, and then the results are compared and contrasted. Results show that the system responses are highly influenced by the structural parameters and the earthquake characteristics, such as frequency content.

Flammable liquid storage tanks usually plant a potential dangerous zone. The damage gets worse and worse. In order to avoid the tank fire, the tanks extended to the nearby storage tanks-facilities and buildings. In consideration of safety conditions, flammable liquid storage tanks for the safety and security distance is necessary. Through the FDS (Fire Dynamics Simulator) computer simulation of fire, flammable liquid storage tanks for spot the fires numerical simulation to detect a fire to happen. In order to establish an optimized model, the flammable liquid storage tanks save the temperature distribution by obtaining flammable safety distance of the liquid storage tank, by talking about the current laws and regulations, by looking forward to meeting the economic and security considerations.

Sloshing of a floating roof in an open-topped cylindrical liquid storage tank under wind loads is investigated analytically. Wind tunnel test in a turbulent boundary layer is carried out to measure the wind pressure distributing over the roof surface. The measured data for the wind pressure is utilized to predict the wind-induced dynamic response of the floating roof, which is idealized herein as an isotropic elastic plate of uniform stiffness and mass. The dynamic interaction between the liquid and the floating roof is taken into account exactly within the framework of linear potential theory. Numerical results are presented which illustrate the significant effect of wind loads on the sloshing response of the floating roof.

In this paper, performance criteria for the seismic design of industrial liquid storage tanks and piping systems are proposed, aimed at defining a performance-based design framework towards reliable development of fragility curves and assessment of seismic risk. Considering “loss of containment” as the ultimate damage state, the proposed performance limits are quantified in terms of local quantities obtained from a simple and efficient earthquake analysis. Liquid storage tanks and the corresponding principal failure modes (elephant’s foot buckling, roof damage, base plate failure, anchorage failure and nozzle damage) are examined first. Subsequently, performance limits for piping systems are presented in terms of local strain at specific piping components (elbows, Tees and nozzles), against ultimate strain capacity (tensile and compressive) and low-cycle fatigue. Modeling issues for liquid storage tanks and piping systems are also discussed, for an efficient analysis that provides reliable estimates of local strain demand. These models are compared successfully with available experimental data. Using those reliable numerical models, the proposed performance limits are applied in two case studies: (a) a liquid storage tank and (b) a piping system, both located in areas of high seismicity.

Seismic response of liquid storage tanks isolated by elastomeric bearings and sliding system is investigated under real earthquake ground motions. The continuous liquid mass of the tank is modeled as lumped masses known as sloshing mass, impulsive mass and rigid mass. The coupled differential equations of motion of the system are derived and solved in the incremental form using Newmark's step-by-step method with iterations. The seismic response of isolated tank is studied to investigate the comparative effectiveness of various isolation systems. A parametric study is also carried out to study the effect of important system parameters on the effectiveness of seismic isolation for liquid storage tanks. The various important parameters considered are: (i) aspect ratio of the tank and (ii) the time period of the isolation systems. It was observed that both elastomeric and sliding systems are found to be effective in reducing the earthquake forces of the liquid storage tanks. However, the elastomeric bearing with lead core is found to perform better in comparison to other systems. Further, an approximate model is proposed for evaluation of seismic response of base-isolated liquid storage tanks. A comparison of the seismic response evaluated by the proposed approximate method and an exact approach is made under different isolation systems and system parameters. It was observed that the proposed approximate analysis provides satisfactory response estimates of the base-isolated liquid storage tanks under earthquake excitation.

Dynamic response of liquid storage tanks isolated by the sliding systems is investigated under real earthquake ground motion. The frictional force of sliding systems is modelled by conventional and hysteretic models. The continuous liquid mass is lumped as convective mass, impulsive mass and rigid mass. The corresponding stiffness associated with these lumped masses is worked out depending upon the properties of the tank wall and liquid mass. The governing equations of motion of the tank with sliding system are derived and solved by Newmark's step-by-step method with iterations. The frictional force mobilized at the interface of the sliding system is assumed to be velocity dependent. For comparative study, the seismic response of isolated liquid storage tank obtained by the conventional model is compared with the corresponding response obtained by the hysteretic model. In order to measure the effectiveness of isolation system, the seismic response of isolated tank is compared with that of the non-isolated tank. A parametric study is also conducted to study the effects of aspect ratio of tank on the effectiveness of seismic isolation of liquid storage tanks. It is found that the sliding systems are quite effective in reducing the earthquake response of liquid storage tanks. In addition, the conventional and the hysteretic model of the sliding system predict the same seismic response of liquid storage tanks. However, the conventional model is relatively more computationally efficient as compared to the hysteretic model.

In the previous paper, the authors had formulated a method of FEM modeling which could be applied to coupling analysis of liquid to structure in various FRP cylindrical liquid storage tanks. We employed multi-point constraint equations in the FEM and found that the simulation coincided well with the experimental results. In this paper, the effects of design parameters of FRP cylindrical liquid storage tanks on bulging frequencies are presented. The design parameters, such as a ratio of height/radius, circumferential stiffeners, Young's modulus of FRP, a radius of filet and a thickness distribution along the height are considered. As a result, the design criteria for avoiding the bulging frequencies to market sizes of FRP cylindrical liquid storage tank are presented and their structural safety is demonstrated under Kobe earthquake load.

Liquid storage tanks are lifeline structures and strategically very important. Water tanks, in particular are important to the continued operation of water distribution system in the event of earthquakes. Most of the failures of large tanks after earthquakes are suspected to have resulted from the dynamic buckling caused by overturning moments of seismically induced liquid inertia and surface slosh waves. Recent earthquakes have shown that liquid storage tanks are found to be vulnerable to damage. The dynamic behaviour of liquid containing structures cannot be estimated by the same approach as for normal building structure as the weight of storage tanks varies in time because of variable liquid storage level. Also there exists sloshing of liquid which influences the response of the tank. Current knowledge about the behaviour of liquid storage tank is extensive, but many of the analytical and theoretical results are for tanks ground supported and open tanks. Therefore, appropriate modeling of the liquid storage tanks is essential for dynamic analysis and seismic response evaluation. In most of the research works, the liquid storage tank has been modeled using two mass model or three mass model concepts. The major difference of these two models is the number of lumped masses into which the liquid column is divided. The two-mass model is convenient for designers to use due to ease but the three-mass model predicts the seismic response more accurately. The objective of the study is to investigate the uncontrolled response of Steel and Reinforced Cement Concrete (RCC) Elevated Water reservoirs of different aspect ratio S = H/R (height of the container to its radius) and subjected to different strong ground motion earthquakes. The simulation of water tank using three-mass model concept is carried out through MATLAB. The paper deals with two H/R ratios viz. 0.6 and 1.85. The governing equations of motion are solved by State Space Method. In the first phase, the response of the tanks to different real earthquake ground excitations is investigated using simplified three mass model of the tank. In the second phase, characteristics of earthquakes are varied and emphasis is given to study their effect on response of the tanks. The response quantities such as sloshing displacement, impulsive displacement, tower displacement and base shear are measured by varying the characteristics of earthquake time history. It is observed that the sloshing displacement is highly influenced by the characteristics of the time history compared to other response quantities.

The effectiveness of a safety device for suppressing incendiary discharges between a rising electrified liquid surface and a protruded earthed conductor inside a liquid storage tank was tested. The device consists of a Teflon disc and is installed by attaching its simple structure to the conductor. Experiments were conducted using a laboratory scale insulating tank containing charged kerosene and an overflow sensor was used to mimic a protruded conductor. Discharges from the kerosene surface t o the overflow sensor with our device attached have their incendivity analysed by examining charge transfer, discharge current and ignition experiment results. The device was found to be able to suppress incendiary discharges better than a bare metal wire linking a protruded conductor to the bottom of the tank which is known to be used in practice.

Liquid-roof interaction imposes a complicated distribution of out-of-plane deformation on the single-deck type floating roof (SDRF), which is the main source of considerable seismic stresses in floating roof. In this paper, an analytical solution for evaluating the dynamic interaction between the liquid and the floating roof is developed. Main physical and geometrical parameters are involved by the proposed analytical solution (PAS) for evaluating the seismic stresses of a single deck floating roof tanks (SDFR). The results of PAS are compared with the results of existing empirical formulas for various dimensions of SDRF tanks. In order to assess the validity of PAS for various sloshing wave height, a numerical model based on finite element method is established and the PAS results are compared with the finite element method (FEM) analysis results. The PAS predictions are in very good agreement with both the available empirical formula and the numerical model results.

Shipyards use labor, materials and capital to turn steel and third party equipment into rigs. Major work activities include welding, material handling, pipe fitting, machinery installation, electrical systems, and outfit materials. Construction requirements include an experienced workforce, land adjacent to a waterway, several cranes, and a large enclosed space for performing high quality welds. Rigs may be built in drydocks or adjacent to a quay. In the U.S., drydocks are not used which necessitates some type of launching system to transfer the constructed rig to the waterway for transportation to market. In this chapter, a high-level narrative of jackup construction is provided with an emphasis on methods used in U.S. shipyards.