Tank Structures Research Articles

Innovation in sustainable composite research: Investigating graphene-reinforced MMCs for liquid hydrogen storage tanks in aerospace and space exploration

The demand for lightweight materials in space exploration applications has seen a significant rise. This study presents a novel approach by integrating graphene with Aluminium alloy (AA) 2900 powder, synthesized through High energy ball milling technique. The resulting powder was used to reinforce Aluminium alloy 2195, creating metal matrix composites (MMCs) via squeeze casting. The findings demonstrate that incorporating 0.5 wt % 2D graphene nanoplatelets (2D-Grnp) in AA 2195 achieved density match, enabling homogeneous dispersion, addressing composite casting challenges. Consequently, the AA 2900 alloy embedded with 2D-Grnp facilitated the homogeneous dispersion of reinforcements during the squeeze casting process, yielding MMCs Ideal for potential use in lightweight liquid hydrogen fuel tank structures for launch vehicles. Following T8 heat treatment, the final casted composite plate exhibited significant enhancements in ultimate tensile strength, with a 4.5% increase over monolithic Al 2195-T8, exhibiting nominal reduction in elongation behavior and higher hardness. Additionally, scanning and transmission electron microscopy (SEM, TEM), Small Angle Neutron Scattering (SANS) and Electron Backscatter Diffraction (EBSD) revealed the squeeze casting technique's effectiveness by exhibiting enhanced bonding among homogeneously reinforced 2D-Grnp, T1/θ’ precipitates, and AA 2195.

Application of Polymer Sheets with Anchor Ribs in the Repair and Reconstruction of Reinforced Concrete Water Supply Storage Structures

The conducted studies have shown that no optimal and effective solution would ensure reliable operation throughout the entire service life of tank structures. The search for effective and innovative technical solutions in this area is a pressing issue. The study aims to determine an effective material for providing secondary protection of a reinforced concrete structure to increase the operational characteristics of tank structures. The conducted experimental studies have shown the possibility of using a polymer sheet with anchor ribs as protection for a reinforced concrete structure. Protection of reinforced concrete structures remains a key aspect of the design and operation of facilities exposed to aggressive media. The conducted studies have shown that there is no optimal and effective solution providing reliable operation during the whole service life of capacitive structures. Search for effective and innovative technical solutions in this area is an urgent task. The research aims to determine an effective material for secondary protection of reinforced concrete structures to increase the operational characteristics of capacitive structures. The performed experimental studies showed the possibility of using polymer sheets with anchor ribs as protection for reinforced concrete structures. The article discusses the use of polymer sheets with rail-shaped anchor ribs for protection of the inner surface of reinforced concrete engineering structures from aggressive influence.

A structural mechanics analysis on a Type IV hydrogen storage tank during refueling and discharging

High-pressure hydrogen gas, as a power generation fuel widely used in transportation, has significantly contributed to the development of hydrogen fuel cell electric vehicles. However, obvious temperature rise and drop during fast refueling and discharging cause serious safety risk to the structural stability of on-board hydrogen storage tank. The American Society of Automotive Engineers SAE J2601 and the international standard ISO 15869 strictly stipulate that the operation temperature range of hydrogen storage tank varies from −40 °C to 85 °C. In this study, a finite element mechanics model was constructed using ACP and Static Mechanical software to better understand the deformation, stress, strain, and failure modes experienced by a Type IV tank during charging and discharging. Detailed parameters such as ply angle, ply thickness, mesh generation, and boundary conditions, were extensively elucidated. The results indicate that the high temperature and pressure generated during fast fueling of the storage tanks are less likely to cause yield failure of the inner, outer layers and plug, but the stress concentration caused by low temperature and high pressure may lead to the fracture rupture of internal polyethylene materials. Aluminum alloy plug, serving as sealing devices for the tank, are most susceptible to yielding failure under coupled conditions. The mechanical load reaching the yield stress of the plug is approximately 85 MPa with the nominal working temperature of 85 °C. Additionally, the maximum stress on the outer layer can be reduced by adjusting the circumferential layer direction from 90° to 70° or by optimizing the orientation of the maximum stress layer increasing it by 110°. The present study can offer new insights into the dynamic loading behavior of the Type IV tanks during fast charging and discharging, and may provide technical references for optimization design of the tank structures.

The modified Swift constitutive model of 304L stainless steel at the cryogenic temperature based on the Olson–Cohen model

The nonlinear behavior of austenitic stainless steel (ASS) is significantly affected by the temperature and strain during plastic deformation. However, the conventional constitutive model is often inadequate to accurately describe its mechanical properties, particularly at cryogenic temperatures. Therefore, the development of a constitutive model for ASS at cryogenic temperatures is of paramount importance in order to fully understanding the performance of liquefied natural gas (LNG) membrane tank structures under such conditions. In this study, we have derived a modified constitutive model using 304L stainless steel that incorporates a phase transition model through theoretical derivations. First, the stress and strain data for 304L stainless steel within the range of 108–293 K have obtained from quasi-static tensile experiments. Subsequently, the XRD test results are utilized to calculate the volume fraction of martensite across various temperatures and strains. Next, a modified constitutive model is proposed by combining the Olson–Cohen phase transition model and the Swift constitutive model. Finally, the accuracy of the modified Swift constitutive model is verified through experimental data. The results demonstrate that the modified Swift constitutive model is precise for characterizing the properties of 304L stainless steel across a wide range of temperatures. Furthermore, multiple case studies have proven the feasibility of using the modified Swift constitutive model to predict the properties of various austenitic materials. By incorporating the Olson-Cohen phase transition model, the modified Swift constitutive model showcases its wide applicability and potential in designing and assessing the safety of ASS structures.

DETERMINATION OF THE OPTIMAL INCLINATION ANGLE OF THE TRUSS FILLER IN A DOUBLE-WALLED TANK

The paper considers the application of the tank wall design, which is a three-layer panel consisting of two shells, between which there is a truss filler. Such a filler is a repeating spatial structure consisting of pyramids or tetrahedrons.The analysis of references concerning such a construction is carried out. As a result of the analysis, it was revealed that the three-layer panel with a truss filler found its application in aviation and rocket engineering, and all studies were carried out for structures with thickness not exceeding 150 mm, and the applied load was evenly distributed over all surfaces.To research the stress-strain state of the tank structure, two numerical models were created in the SCAD Office software package. All active loads are collected. The calculation was carried out for tank structures, in the inter-wall space of which pyramids and tetrahedrons were located.The technology used relates to cross-cutting digital, namely digital design and modeling, which is currently included in the concept of technological development of our country.The search for the optimal inclination angle of the rods was carried out in the range from 40° to 60°. Five calculations were performed for each placeholder in the corresponding ranges.As a result of geometric parameters dependencies researches of the double-walled tank wall, the inclination optimal angles values of the pyramidal and tetradrael rods fillers for the wall of a tank of 50000 m3volume were obtained. There are obtained dependences to determine the optimal inclination angle of the rods of the truss filler for a tank of any volume, using relative values, as well as the values of forces arising in the rods of the filler depending on the hydrostatic column of the liquid.

Evaluating Residual Strength of RCC Tanks Affected by ASR Using NDT Methods

This case study focuses on the groundwater level tanks (GLR) located in Netra Village, 35 km from Jodhpur, on Nagour Road. The investigation revealed that people and livestock in the area were grappling with water scarcity issues. Non-Destructive Testing (NDT) methods were employed to assess the residual strength of three tanks in the region. The results showed that Tank-1 had a residual strength of 35.41%, Tank-2 had 63.08%, and Tank-3 had 53.8%. Alkali-silica reaction (ASR) poses a significant threat to the structural integrity of concrete tanks, necessitating accurate and non-destructive methods for residual strength assessment. This research paper delves into the effectiveness of NDT methods, specifically rebound hammer and Ultrasonic Pulse Velocity (UPV), in evaluating the residual strength of ASR-affected tanks. Through an extensive review of literature, case studies, and experimental data, this study aims to shed light on the practical application of rebound hammer and UPV for ASR assessment in tank structures. The paper discusses the principles, advantages, and limitations of each NDT method, emphasizing their ability to detect ASR-induced damage and predict the remaining structural capacity of tanks. Moreover, the research addresses the challenges associated with implementing rebound hammer and UPV techniques in ASR-affected environments, offering recommendations for enhancing their reliability and accuracy. By harnessing the combined capabilities of rebound hammer and UPV, engineers and asset managers can make well-informed decisions regarding the maintenance, repair, and retrofitting of ASR-affected tanks, ensuring their long-term safety and functionality in critical infrastructure applications.

Hydrogen permeability testing of fibre reinforced thermoplastics under cryogenic conditions – validation of a test rig concept

The need to decrease the gross weight of cryogenic hydrogen fuel systems in future zero emission mobility leads to increasing activities in the field of cryogenic lightweight engineering. Fibre reinforced thermoplastic composite materials (FRT) are considered for cryogenic applications despite their bias towards permeation. However, permeation through plastic materials is of major concern in cryogenic applications. Even tiny fluxes can very much compromise the insulating power of high vacuum spaces required for insulation of cryogenic systems such as tank structures or transfer lines. Hence, it is essential to qualify those FRT in terms of their hydrogen permeability for future usage in mobile cryogenic applications. The conventional concepts for measuring permeability in plastic materials are not sufficient for cryogenic measurements of FRT as shown in a previous paper. For that, a novel laboratory test rig concept was proposed. In this paper, we validate this concept and show its eligibility for measuring permeation of hydrogen through thermoplastic materials. Therefore, we report results of helium permeation through polytetrafluoroethylene (PTFE) at room temperature and compare those results to literature permeability data.

Cylindrical Steel Tanks Subjected to Long-Duration and High-Pressure Triangular Blast Load: Current Practice and a Numerical Case Study

This paper presents an investigation into the design of ammonia tanks for long-duration and high-pressure blast loads. The focus is on cylindrical steel tanks that apply as outer pressure-tight containers for double-walled tanks storing refrigerated liquefied gases. Based on limited empirical data, it is known in the tank industry that these tanks can withstand an explosion pressure up to a peak overpressure of approximately 10 kPa and 100 ms positive load duration. However, there is a growing need to design tanks for higher peak overpressures in order to establish a higher safety standard and accommodate unforeseen future requirements. This paper explores the concept of adapting established steel tank designs to handle high-pressure and long-duration overpressure due to blast events. Numerical analysis is conducted on a representative steel tank geometry subjected to a triangular blast load of 30 kPa with a 300 ms positive load duration. Various load application and calculation options are analyzed numerically. Considering the challenging nature of analyzing tank structures under blast load, the paper addresses controversial aspects discussed in the literature and presents a suitable analysis concept for a deflagration blast scenario for cylindrical tanks. The results provide insights into the expected structural behavior of the tank under high-pressure and long-duration overpressure. The main finding is that the calculation method developed in this study demonstrates the feasibility of utilizing steel tanks in scenarios involving long-duration and high-pressure blast loads. Furthermore, the paper provides recommendations to guide future studies in this area. The findings have implications for the design and construction of tanks in critical infrastructure and offer valuable insights for engineers and researchers in this field, improving safety standards and ensuring adaptability to future utilization concepts.

Structural analysis and optimal design of a spherical thin-walled stainless steel water tank without reinforced tie ribs

A spherical thin-walled stainless steel water tank without reinforced tie ribs has been designed to address the issues of easy fracture and corrosion of the ribs, difficulty in maintenance and cleaning, and short service life exposed during the use of thin-walled stainless steel water tanks with reinforced tie ribs. Firstly, an analytical model of a flat steel thin-walled water tank without reinforced tie ribs was established and subjected to static analysis under water pressure. The deformation and stress distribution patterns of the side molded plate of the flat box were obtained. Secondly, a spherical non ribbed thin-walled stainless steel water tank structure was designed with circular cross-section under different box bulge parameters, and its mechanical response characteristics under water pressure load were analyzed. A strengthening scheme was designed for the bottom box molded plate. Once again, optimize the combination design of the box scheme and the reinforcement scheme, and analyze their static, thermodynamic, and thermal solid coupling performance. Finally, the Latin Hypercube Sampling method was used to generate experimental design samples, and a response surface approximation model of a spherical thin-walled stainless steel water tank without reinforced tie ribs was constructed. The wall thickness of the box molded plate, skeleton, and reinforcement were used as design variables, and the maximum deformation and maximum equivalent stress were used as constraints. The lightweight design was carried out with the goal of minimizing mass. The research results indicate that the design program and parameter selection method for spherical thin-walled stainless steel water tanks without reinforced tie ribs proposed in the article are efficient and feasible, and can provide technical reference and theoretical support for the layout and overall optimization design of non ribbed thin-walled stainless steel water tank structures.

Optimization and comprehensive evaluation of liquid cooling tank for single-phase immersion cooling data center

Single-phase immersion cooling has emerged as a highly promising solution for addressing energy challenges and the substantial heat dissipation demands in data centers (DCs). The liquid cooling tank is a curial component in such system where numerous servers are immersed and the coolant are evenly flowed to each server. However, its performance and the comprehensive evaluation for the tank have not received much attention. In this study, by using the validated numerical model, the different tank structures, with or without consideration of baffle and porous panel, were firstly discussed. Then, four key parameters of tank, including inlet flowrate (Parameter A), the ratio of separation chamber height to server height (Parameter B), the ratio of pressure chamber height to server height (Parameter C), and the porosity of the porous panel (Parameter D) were explored in detail. Finally, the tank performance is evaluated and optimized by the orthogonal analysis and the entropy weight method (EWM). Results showed that, flow uniformity within the tank can be enhanced by incorporating a porous panel, and it was advisable to minimize the gaps between servers, despite the potential increase in pressure loss. Parameter A significantly impacted both the maximum temperature and pressure loss. Parameters B and C demonstrated effects on coolant weight and pressure loss, while Parameter D influenced pressure loss. By using orthogonal analysis and the EWM, maximum temperature carried the highest weight (0.362), followed by temperature difference (0.245), coolant weight (0.216), and pressure loss (0.177). The recommended values for Parameters A-D were 4 m3/h, 1.35 %, 4.05 %, and 11.33 %, respectively, which could be also considered as universality, since the comprehensive evaluation index only changed by 8 % when the server number increased from 10 to 40.

Numerical analysis of thermal and hydrodynamic characteristics in aquaculture tanks with different tank structures

Improving hydrodynamic performance by changing the geometries of aquaculture tanks can facilitate salmon growth. Thus, this study proposed to redesign the aquaculture tank by varying the tank shape, numbers of inlets, and nozzle angles. The hydrodynamic and thermal characteristics of an aquaculture tank were numerically investigated via computational fluid dynamics simulations. The results indicated that the circular tanks mixed better than the octagonal tanks. Secondary vortices were more extensive in a two-inlet than a one-inlet tank. The vortex column in a two-inlet tank was smaller than that in the one-inlet tank. Therefore, the mixing performance of the two-inlet tank was better than that of the one-inlet tank. Further, the flow uniformity could be improved by optimizing the nozzle angle. Consequently, the mixing performance of the radial nozzle tank was better than that of the tangential nozzle tank because the secondary vortices were prominent and vortex column was smaller. A comparison of all the cases revealed the flow uniformity of the radial nozzle case was the highest. The volume percentages corresponding to the suitable velocity for salmon growth and velocity uniformity were 52.27% and 0.878, respectively. Furthermore, the vortex size was reduced and the velocity uniformity was increased by 2.23% by changing the nozzle angle to a radial angle. Therefore, changing the nozzle angle along the radial direction better improved the hydrodynamic characteristics.

До визначення стійкості руху автопоїзда з частково заповненою цистерною

When designing and manufacturing tanks for the transportation of liquid cargo, it is necessary to take into account the shape of the tank, the level of liquid filling and the natural frequency of splashing of the liquid in the tank, as they are important factors and affect the stability of the movement. Due to the uncertainty of the lateral forces acting in a partially filled tank, the maximum speed of the start of braking, at which the stability of the movement is still ensured, can be taken as the main indicator of the lateral stability of the tank train. When studying the stability of a road train, as a rule, plane-parallel movement of its links is considered. At the same time, it is considered that the normal reactions of the support surface on the starboard and port wheels are the same. Under this condition, stability of movement is considered for a flat model of a road train. However, when the road train is moving with a partially filled tank, the reactions of the support surface on the wheels of the road train links may change significantly. To determine this phenomenon, the equations of the road train were compiled both in plane-parallel motion and in the longitudinal vertical and transverse planes. 
 The integration of the equations of motion is performed for a road train consisting of a DAF XF95 tractor and a tank semi-trailer filled to 50 % (8000 L) and the same road train with the same rigid load. As a result of the integration of the obtained system of equations, it was established that during braking of a road train with a partially filled tank, due to the movement of liquid in the tank itself, a lateral force arises, which depends on a large number of factors that cannot be determined analytically. This force leads to a change in the normal reactions of the support surface on the wheels of the axles and sides of the road train. At the same time, the reaction on the wheels of both sides of the tractor vehicle increases, and on the wheels of the semi-trailer - decreases. This is explained by the effect of liquid cargo on the walls of the tank. At the same time, it is shown that the generalizing parameter that characterizes the stability of the straight-line movement of a road train with a partially filled tank (50 % of the full volume) in the braking mode should be taken as the initial speed at which the tractor and semi-trailer do not exceed the width of the traffic lane. Based on the selected criterion, the initial braking speeds are obtained, at which the stability of the road train is ensured. These velocities, with a coefficient of adhesion of the wheels to the supporting surface in the range of j = 0.6, were 16.1 and 26.9 m/s for the road train with hard and liquid cargo, respectively. Therefore, it is necessary to provide special devices in the tank structures, in particular internal partitions, which would increase the stability of the road train during the braking process.

Seismic Vulnerability Analysis of Steel Clarification Tank

As a physical analysis method, susceptibility not only predicts the probability of failure of a structure under different hazard levels but also prevents disasters induced by structural damage due to vulnerable members. To study the susceptibility of steel clarification tank under earthquake action, this study analyzes the dynamic response of steel clarification tank under near-field impulse, near-field no impulse, and far-field ground shaking, derives IDA curve clusters by incremental dynamic analysis method, and conducts related studies to analyze the susceptibility of clarification tank structures through susceptibility curves. The results of the study show that the probability of failure of the clarification tank under different ground shaking intensities is different. The probability of liquid wave height transcendence of the clarification tank under seismic action is the largest, the probability of liquid wave height transcendence of the clarification tank under near-field pulsed seismic action is the second, the probability of liquid wave height transcendence of the clarification tank under near-field nonpulsed seismic action is the smallest, and the probability of transcendence occurs similarly in near-field pulsed and far-field seismic actions.

СЕЙСМОСТІЙКІСТЬ ВЕЛИКОРОЗМІРНОГО РЕЗЕРВУАРУ ДЛЯ ЗБЕРІГАННЯ МЕТАНОЛУ

The paper contains the methods of analytical modeling of the seismic loads at the large-sized tanks in the form of impulsive and convective hydrodynamic pressures of the liquid. Have been performed the simulation of the stress-strain state of the tank by the finite element method basis on the developed mathematical models of seismic impact. The simulation takes into account the distortion of the tank’s geometry, obtained as a result of long-term operation and reduction in the strength of tank structures due to corrosive wear. Have been considered the generally accepted foreign method for calculating seismic resistance for assessing the strength and durability of tank’s building structures. The method is adapted to the requirements of national standards. Have been revealed that the most dangerous state for the tank is seismic action with a horizontal direction cosine as a result of the analysis of possible design situations. Have been performed the numerical calculations using the proposed method of analytical modeling of seismic impact for a tank with a volume of 20 000 m3, built in the Yuzhny city, Odessa region. Have been determined the estimated height value of the excited wave, which can appear on the surface of methanol during a seismic shock. Have been proven that in order to preserve the integrity of the roof structures, as well as to ensure the seismic resistance of other structures, the filling of the tank with the product should be limited to 61% of the total design capacity. Have been verified the most overloaded sections of the shell, which are the supporting layers of the side wall, as well as the most probable limit conditions during a seismic shock (buckling).Have been developed the technological regulations for further safe operation of tank based on seismic resistance and outlined directions for further scientific research on this topic.

Numerical modeling of internal flows in tanks with baffles

The proposed article presents the materials of experimental and mathematical studies of internal inertial flows of an incompressible liquid during its fluctuations in tanks. An analysis of modern problems related to the harmful effect of liquid resonant splashing on tank structures, as well as on the trajectory and nature of the object movement itself with the liquid, was carried out. The use of damping baffles and guide devices in similar closed flows allows to fundamentally change the structure of internal flows, reducing gradients of shock pressures in flows, as well as redistributing the main liquid inertial effects. Numerical modeling of such flows qualitatively confirms the results of experimental studies and allows us to build a rather complex three-dimensional development picture of fluctuations in fluid flows. In addition to the use of the damping baffles structures, it is proposed to make the plane of baffles perforated with different degrees of permeability due to the diameter of the holes and their number. The effect of hydraulic resistance occurs when flow energy is lost due to overcoming artificial obstacles in the form of holes of small diameter. Thus, the shock effects of the flow on the walls of the tank are predicted to have a smaller amplitude and duration. The use of the proposed dampers labyrinth structures allows to control the force effects of the liquid only by hydraulic means and thus reduce the number and dimensions of the internal guide devices.

Influence of Impeller and Mixing Tank Shapes on the Solid–Liquid Mixing Characteristics of Vanadium-Bearing Shale Based on the DEM-VOF Method

The mixing tank is important equipment for industrial applications in the wet vanadium extraction process, but in practice, there are problems, such as uneven mixing of minerals. In this study, the effect of different types of impellers and different mixing tank structures on the suspended mass of particles was simulated using the discrete element method and volume of fluid method (DEM-VOF). The simulation results show that the round-bottomed tank performed mixing better than the flat-bottomed tank at different particle densities, and the flat-bottomed tank was prone to particle stratification and other phenomena. The round-bottomed mixing tank could better improve the solid–liquid suspension effect. In this study, the coefficient of variation σ was introduced to characterize the suspended mass of particles. By monitoring the σ value, it was found that the blade pitch angle 45 (BPA45) had the best mixing uniformity in the inclined pitched blade turbine (PBT). As the PBT impeller pitch angle increased, the particle suspension increased. When comparing different types of impellers, the Rushton exhibited a 45% improvement in mixing uniformity relative to the BPA45. Second, the width and height of the trough bottom projection were optimized and their σ values were calculated separately for different parameter conditions. The width of 0.05 m and height T/4 (T being the diameter of the tank) were finally determined to be the optimum parameters for the optimal design of the vanadium shale leaching mixing trough.

Design optimization of multi-functional multi-lobe cryogenic fuel tank structures for hypersonic vehicles

Hypersonic hydrogen-powered cruise vehicles offer promise for economical and reliable high-speed atmospheric transport. In recent years, several vehicle concepts have been developed in which the integration of fuel tanks is a major challenge, as they feature complex aerodynamic designs. In this work, we explore the viability of multi-lobe hydrogen tanks as a solution to obtain lightweight and volume-efficient structures. To do so, a parametric finite-element model was developed to fit multi-lobe geometries inside hypersonic vehicles. The parametric model was then incorporated into an optimization that minimizes the mass and maximizes the fuel capacity of the tank. The methodology is organized in two steps: the global search is driven by a two-level optimization consisting of a genetic algorithm with a nested gradient-based method; and a local search where each design is further improved to obtain a Pareto front. As presented in the results, this is a promising approach for designing multi-lobe tanks for complex geometries.

Effect of simplified wind girder modelling on MNA-LBA analysis of open steel tanks

The MNA/LBA design methodology for metal shells, including open-top tank steel shells, plays an important role in the European Standard on Strength and Stability of Shell Structures. However, when using this design format, particular doubts as to the correctness of the obtained results may arise when simplifications are used in modelling of key elements of tank structures in order to improve modelling and numerical calculation processes. This paper presents the results of numerical studies that address the question of how the simplifications in the modelling of the primary wind girder affect the values of the elastic buckling resistance and the plastic reference resistance determined from linear bifurcation analysis (LBA) and materially nonlinear analysis (MNA), respectively. Forty-two computational models of wind-loaded open storage tanks with three height-to-diameter ratios and with variable or constant wall thickness of a cylindrical shell, equipped with six different representations of the wind girder, were investigated in order to provide guidelines in the above-mentioned scope. It has been proven that the applied simplifications in the modelling of the primary wind girder allows for relatively faithful representation of the reference models, i.e. models in which the stiffening ring was modelled using shell finite elements, in the LBA analysis. In turn, a varied influence of the applied simplifications in modelling on the results of the MNA analysis was observed. The obtained results indicated a limited range of applicability of the results of the materially nonlinear analysis for the formal assessment of the relative overall slenderness of the considered shells. Finally the obtained results allowed for the formulation of practical conclusions for the purposes of design of open-top steel tanks using the MNA/LBA methodology.

Effects of reinforcing steel tanks with intermediate ring stiffeners on wind buckling during construction

Many tank structures may not be stable during the construction phase, and this may lead to their becoming vulnerable to buckling under environmental loading conditions such as wind. Installing intermediate ring stiffeners of the proper size at the mid-height of the cylindrical shell may be the most effective way to stabilize these structures, especially under the effects of wind action. In the study, analytical and numerical studies were conducted to identify the required strength and stiffness for the intermediate ring stiffener. First, a new cylindrical shell-to- intermediate ring stiffness ratio was derived by considering curved beam and shell membrane theories. For strength criteria, the tributary height and the effect of shell- ring interaction on the internal forces and moments were examined by making use of Linear Analysis (LA) and Geometrically Nonlinear Analysis (GNA). The stress resultants developed in the intermediate ring stiffener were identified so that they could be used as strength criteria. For stiffness criteria, by considering the changes in the buckling resistance based on the developed stiffness ratio, an expression to compute the minumum intermediate ring stiffness was determined. In addition, Geometrically Nonlinear Analysis including Imperfections (GNIA) was also performed to examine the effect of the geometric imperfections on buckling strength of the steel tank with an intermediate ring stiffener, taking different imperfection amplitudes into account. The developed design equations in simple algebraic form can be utilized for the structural stability of cylindrical steel tanks during erection.

Design and Comparative Study of Overhead Tank Subjected to Seismic Forces in Different Zones

Overhead tank are generally classified as Ordinary Moment Resisting Frame (OMRF) and Special Moment Resisting Frame (SMRF) supported response reduction factor. Generally, the Overhead tank consists of structural members like slabs, beams, columns, and footings, where the subjected loads are transferred between the structural members and eventually transferred to the Sub-grade of the soil. The behavior of the Overhead tank is different for various sorts of loadings (Dead, Live, Wind, and Seismic) within the analysis and of overhead tank usefully Indian standards codes suggest various loads combinations supported probability of Occurrence. There are around 52 load combinations and IS codes suggest the lateral load (wind and seismic) acts independently but the load governing the planning of structural members is to be acknowledged. and therefore the present study to research the consequences of wind and seismic forces on Overhead tank structures of heights (15m) are considered in seismic zones II, III, IV, V where length and width of the structures are kept constant. An earthquake load is calculated as per IS and wind pressure calculated as per IS 875-1987. The analysis is done the use of STAAD.pro software.