Nonlinear Finite Element Analysis of Unanchored Steel Liquid Storage Tanks Subjected to Seismic Loadings

Kim

Mathematical Problems in Engineering

2019

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.

Section: Fe Model Of Steel Liquid Storage Tankmentioning

confidence: 99%

Seismic Fragility Analysis of Steel Liquid Storage Tanks Using Earthquake Ground Motions Recorded in Korea

Kim

Mathematical Problems in Engineering

2019

Earthq Engng Struct Dyn

“…9 The seismic behaviour and fragility analysis of above-ground liquid storage tanks, including relevant failure modes, has been investigated using models of different complexities. 6,[10][11][12][13][14] In the framework of quantitative risk analysis of liquid storage tanks, fragility functions can be defined in the form of probit functions. 15 However, damage states may be defined by engineering demand parameters (EDPs) obtained from the seismic analysis.…”

Section: Introductionmentioning

confidence: 99%

“…Few recent experimental studies have focussed on the stress distribution on the tank wall in above-ground liquid storage tanks. 18,19 Many researchers 12,13,20 studied above-ground liquid storage tanks using refined FE models. Their studies focussed on two models applied to the liquid domain: an arbitrary Lagrangian-Eulerian model 12 and an acoustic model.…”

Section: Introductionmentioning

confidence: 99%

“…18,19 Many researchers 12,13,20 studied above-ground liquid storage tanks using refined FE models. Their studies focussed on two models applied to the liquid domain: an arbitrary Lagrangian-Eulerian model 12 and an acoustic model. 13,20 Although wall buckling may lead to leakage and loss of tank containment, non-linear effects or large deformations affecting the tank wall due to EFB have not been thoroughly studied.…”

Section: Introductionmentioning

confidence: 99%

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A risk‐targeted seismic performance assessment of elephant‐foot buckling in walls of unanchored steel storage tanks

Munoz

Dolšek

2023

Unanchored steel storage tanks are used in industrial plants to store oil and other petrochemical liquids. In a major earthquake, such tanks may sustain different types of damage, including elasto‐plastic buckling in the shape of an elephant's foot, which is the object of the research. The methodology introduced in this paper consists of cloud‐based 1D site response analysis (SRA) and pushover‐based seismic performance assessment of the tank wall using a 3D non‐linear model of the tank. The SRA, which considers the recorded ground motions on the rock outcrop and the sample of interval shear‐wave velocity profiles, is carried out to estimate spectral accelerations at the tank impulsive period. By adopting the code‐based model of hydrodynamic pressures, the seismic demand on the tank wall is then calculated by pushover analysis. The risk‐targeted decision model is used for safety verification. The proposed methodology is demonstrated through an example of a large liquid storage tank for which it is shown that the fragility function for peak ground acceleration at the rock outcrop is on the left side of the target fragility function, indicating that the tank cannot be considered safe from elephant‐foot buckling. The introduced assessment process is relatively simple if the cloud‐based SRA is automated. However, further experimental and numerical investigations are required to confirm the validity range of the pushover analysis for the seismic performance assessment of tanks.

“…Recently, a nonlinear static pushover analysis of unanchored steel liquid tanks was proposed by Vathi and Karamanos [17], where the distribution of hydrodynamic pressures on the shell plate is calculated and applied to the steel tank model by a loading subroutine in ABAQUS software. Phan et al [18,19] proposed full nonlinear finite element models of an unanchored tank using ABAQUS software, using both Arbitrary Lagrangian-Eulerian and Structural Acoustic Simulation methods. The results of their analyses are in good agreement with the experimental data and demonstrated the suitability of both models.…”

Section: Introductionmentioning

confidence: 99%

Seismic response and damage evaluation for anchored and unanchored cylindrical above ground steel tanks

Phan¹,

Nguyen²,

Hoang³

2022

UD-JST

This paper aims to first present a review of studies on numerical modeling and seismic response analysis of above ground steel liquid storage tanks. On that basis, a procedure for estimating dynamic parameters associated with simplified models for anchored and unanchored conditions together with calculation methods of seismic responses and damage states of tanks are presented. In which, the nonlinear behavior of the bottom plate in the case of unanchored conditions caused by sliding and uplift phenomena is properly modeled based on the nonlinear static pushover analysis on a 3D finite element model. Finally, an example of the numerical modeling and seismic response analysis of a water tank is presented. The seismic responses and damage of both anchored and unanchored conditions are compared and evaluated in detail.