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The current investigation delved into the seismic analysis, design intricacies, and assessment of the response of elevated steel containment tanks when supported by concentrically braced frames. The primary focus was placed on comprehending the behavior of the supporting structure, recognizing its heightened vulnerability to damage under horizontal excitation—insights gleaned from reconnaissance teams studying earthquake aftermaths worldwide. A specific case study unfolded featuring a steel concentrically braced frame as the supporting structure, aligning with prevalent industry norms. Throughout the entire process, spanning design phases, seismic vulnerability assessments, and response evaluations, special emphasis was placed on the internal fluid sloshing phenomena. This nuanced consideration plays a pivotal role in shaping the dynamic response of the system. The study introduces two distinct design methods: the first method aligns with relevant international codes, while the second method innovatively incorporates the compressive strength of the braces into its approach. To evaluate the dynamic response of the elevated tank, both linear and nonlinear advanced analyses were employed. The comparative analysis of various strategies underscores the impact of the chosen design methodology on the overall system response. This multifaceted exploration aims to contribute valuable insights to the seismic resilience and design optimization of elevated steel containment tanks, furthering the understanding of their performance under seismic forces. [ABSTRACT FROM AUTHOR]

An adequate seismic protection of steel storage tanks of industrial, chemical and petrochemical plants is essential since potential consequences of failures, besides the economic losses, can be catastrophic for the environment and for people living nearby. Among the most common damages suffered by steel tanks in recent earthquakes, there are the elephant‐foot‐buckling of the perimeter wall and the tanks' uplift or overturning. Due to the uncertainties related to the estimation of the mechanical properties of filled tanks and related seismic loads (i.e. dynamic overpressures generated by the content), conventional design approaches may lead to unsafe or, on the contrary, oversized solutions. Among effective alternatives, base isolation through Curved Surface Slider isolators (CSSs) offers some valuable advantages like high load bearing and displacement capacity with compact dimensions, independence of the oscillation period on the supported mass, and minimisation of torsional effects. Despite being neglected by most common commercial FEM codes, as a drawback, recent studies pointed out that the initial peak of friction force at CSSs' motion breakaway can lead to significantly increased lateral deformations and accelerations of the superstructure. Within this framework in this study, a refined numerical model is developed in OpenSees FEM code, and an exhaustive parametric study is carried out to investigate the effect of the breakaway on isolated tanks providing some useful insights for the selection of the most suitable isolators. [ABSTRACT FROM AUTHOR]

This study provides a framework for investigating the seismic response of an elevated steel water tank within a reinforced concrete chimney, to assist optimal tank placement and analyse different tank geometries. Elevated tank design procedures in different guidelines and codes are adequate for specific cases, none of which meets the exact requirements of this case study, in which the supporting structure mass is large relative to the storage tank. The tank is located at an elevation 63 m below the mid-height of the 200 m chimney, resulting in a different behavior than a simple cantilever. Furthermore, for certain H/R ratios, coupling effects may exist between the fundamental period of the chimney and that of the sloshing wave. An equivalent model is examined that is simple enough yet able to accurately produce the design acceleration, dynamic amplification, damping and torsional effects at the chosen tank location, and to capture site effects. An analysis of the tank at ground level is conducted according to AWWA D100-11. Then, the tank at elevation 63 m is analysed within the framework of three existing methods using code spectra and site-specific spectra. A novel fourth method is then proposed which, contrary to the existing methods, can accurately capture the conditions of this case study by combining the benefits of all methods. The workflow described here can be readily applied to other cases of elevated tanks for which the standard procedures are inadequate. [ABSTRACT FROM AUTHOR]

Field observations following the May 2012 Emilia, Italy, earthquakes have revealed the seismic vulnerability of storage steel tanks typical of the past Italian design practice, highlighting structural deficiencies observed during previous events in other areas and mostly related to lack of structural seismic design and detailing, lack of redundancy, and inadequate anchorage design and execution. Damage was disproportionately high, considering the moderate size of the events (MW = 6.11 and MW = 5.96 on 20th and 29th May, respectively). Failure modes observed are reported and classified. Comparison is provided with the results of high-definition finite element (FE) dynamic simulations, performed on tanks representative of those inspected. Numerical analyses, accounting for material and geometrical nonlinearities, at the element level, as well as for fluid-structure interaction through highly nonlinear methods, were able to capture the stress/strain concentrations that caused them to collapse. Elephant's foot and diamond buckling induced by hydrodynamic pressures as a result of inertial forces imparted during the earthquakes were reproduced, as well as shear-buckling failure of leg-supported tanks or sliding of unanchored systems. [ABSTRACT FROM AUTHOR]

Liquid storage tanks are widely used in the industry and can contain not only harmless substances but also various ones that can be explosive and toxic or pollutant, thus implying that both the structure and the content must remain safe and operational under different types of loading. The same applies to any tank-connected plant system/item. Yet, past earthquakes repeatedly demonstrated that even if structural damage is prevented in the shell, severe occurrences may still be observed due to sloshing phenomena, which drive the tank-fluid system response with high impacts in case of accidental release of chemicals. Therefore, this paper studies an energy dissipation system consisting of floating roof and external dampers that are utilized to control liquid vibration by augmenting the level of damping. In order to evaluate its effectiveness at the design-level earthquakes, a series of explicit nonlinear dynamic analyses have been performed, and comparisons are provided between floating roofed steel cylindrical tanks equipped with supplemental devices and counterparts without them. Changes in seismic performance because of geometrical variations in the tank (i.e. aspect ratio) and seismic input (i.e. far and near field earthquakes) have been quantified by means of experimentally validated numerical models that account for material and geometrical nonlinearities, as well as for fluid-structure interaction in an explicit manner. Shake-table tests available in the literature have been simulated, and the proposed modelling criteria show a good fit with experimental data on two tank specimens. Analysis data sets involving three tank geometries reveal that even if the dissipation system targets mainly large-capacity tanks, it can be effectively used to enhance the performance of any system, reducing the sloshing wave height which can be excessive especially when the tank is subjected to severe near field ground motions. • Dynamic response of liquid storage tanks with floating roof is examined numerically. • Tanks with floating roof are analysed with and without dampers used to control liquid vibration. • Experimentally validated numerical models are developed to simulate different tank geometries. • Nonlinear sloshing of the fluid is reproduced by the Arbitrary Lagrangian-Eulerian formulation. • Sloshing wave height peaks can be effectively reduced, thus mitigating damage and related issues. [ABSTRACT FROM AUTHOR]