Seismic Analysis of a Large LNG Tank Considering Different Site Conditions

Abstract

Seismic resilience of critical infrastructure, such as liquefied natural gas (LNG) storage tanks, is essential to the safety and economic well-being of the general public. This paper studies the effect of different ground motions on large LNG storage tanks under four different site conditions. Key parameters of structural design and dynamic analysis, including von Mises stress of outer and inner tanks, tip displacement, and base shear, are analyzed to directly evaluate the safety performance of the large LNG tanks. Because the size of an LNG tank is too large to perform any experiments on a physical prototype, Smoothed Particle Hydrodynamics-Finite Element Method (SPH-FEM) simulation is used as a feasible and efficient method to predict its seismic response. First, the accuracy of the SPH-FEM method is verified by comparing sloshing frequencies obtained from theoretical formulation to experimental results and SPH-FEM models. Then, the seismic response of a real-life 160,000 m3 LNG prestressed storage tank is evaluated with different liquid depths under four site classes. Simulation results show that the tip displacements of the LNG tank at liquid levels of 25% and 50% under site class IV are nearly identical to that of 75% and 100% under site class II. In addition, the maximum von Mises stress of the inner tanks exceeds 500 MPa in all four site classes and jeopardizes the structural integrity of large LNG tanks. As a result, optimization of structural design and the establishment of an early warning system are imperative to the safety of LNG tanks at high liquid levels.

Nonlinear behaviour of liquefied natural gas tanks with different seismic isolation systems

“…The steel tank forming the inner layer is composed of a nickelcontaining steel alloy (9 % Ni). Because of this steel alloy, the inner layer tank exhibits excellent low-temperature resistance, good weldability and low susceptibility to cold cracks [3,26]. As shown in Fig.…”

“…Zhao et al [25] investigated the effects of liquid filling rate and earthquake motion periods on the efficiency of a leadrubber bearing system using the ABAQUS program. Zhao et al [26] investigated the liquid filling ratio and earthquake motion periods to determine the efficiency of a lead-rubber bearing system using the general finite element code ABAQUS. They analysed a 160,000 m 3 LNG prestressed storage tank for 12 earthquake waves under four site classes using stress distributions on the outer and inner tanks, as well as tip displacement and base shear.…”

Detailed Structural Analysis of Cylindrical Steel Tank Subjected to Various Seismic Peak Ground Values Using FSI Approach

“…Zhao et al [26] analyzed the fluid-solid coupling problem in the seismic analysis of large LNG tanks to predict seismic response efficiently and accurately by adopting the method of Smoothed Particle Hydrodynamics-Finite Element Method (SPH-FEM). This method inherited the advantages of SPH in modeling fluid behavior while preserving the advantages of FEM in simulating FSI problems.…”

Effect of MetaFoundation on the Seismic Responses of Liquid Storage Tanks

“…The reported failure modes of these structures during past earthquakes indicate their inappropriate seismic performance [1,2] and the need for a safeguard against seismic events. The seismic behaviour of liquid storage tanks has been studied extensively (e.g., [3][4][5][6]). Generally, two approaches can be followed to improve the performance of liquid containers against seismic events.…”