Evaluation of the adequacy of a spring‐mass model in analyses of liquid sloshing in anchored storage tanks

Abstract

This research addresses the influence of the load characteristics, that is, frequency content and maximum acceleration, on the wall stresses of an anchored water storage tank. A low-density polyethylene tank with a range of six different aspect ratios (water height to tank radius) was tested using a shake table. Eight sine excitations that cover the lowest free vibration frequency of the tank-water system were applied. Additionally, two sets of five Ricker wavelet excitations were utilized. Each set represents potential earthquakes with a bandwidth between a low and a high dominant frequency. The experimentally determined maximum stresses and those obtained from calculations using a common spring-mass model employed for seismic analysis of tanks were compared. The results reveal that the relationship between the excitation frequency and the wall stresses strongly depends on the sloshing behavior, especially when the frequency of loading is in the vicinity of the lowest freevibration frequency of the tank-water system. When the frequencies are dissimilar, there is a proportional relationship between stress and the maximum acceleration of the excitation. The spring-mass model was found to underestimate both the maximum hoop stress (for aspect ratios greater than two) and axial stress (for aspect ratios equal to 0.5). This occurs because is the spring-mass model cannot capture, in all cases, the contribution of chaotic sloshing to wall stress.

Hazard consistent record selection procedures accounting for horizontal and vertical components of the ground motion: Application to liquid storage tanks

“…56 The former is known as the impulsive mass (m i ) component and is tied to the uplift mechanism that can potentially trigger elephant's foot buckling (EFB) of the tank wall 55,57 and base plate damage 55,[58][59][60] ; the latter forms the convective mass (m c ) component, which can cause damage at the upper courses of the tank wall and/or the roof. 58,61,62 While several reduced-order models are available in the literature regarding the seismic response of liquid storage tanks, the vast majority ignores the effect of the vertical ground motion component, focusing only on the application of the horizontal one(s). [63][64][65][66][67][68][69] Contributions that account for the vertical ground motion component in the response of liquid storage tanks are included in a handful of studies.…”

“…During a strong ground motion, part of the contained fluid in a liquid storage tank oscillates rigidly with the tank wall, while the remaining portion exhibits long‐period oscillations that result in sloshing of the free fluid surface 56 . The former is known as the impulsive mass ( m i ) component and is tied to the uplift mechanism that can potentially trigger elephant's foot buckling (EFB) of the tank wall 55,57 and base plate damage 55,58–60 ; the latter forms the convective mass ( m c ) component, which can cause damage at the upper courses of the tank wall and/or the roof 58,61,62 …”

Lid induced sloshing suppression and evaluation of wall stresses in a liquid storage tank including seismic soil‐structure interaction

“…The transformation of a sloshing pattern from planar to nonplanar and eventually to chaotic has been observed in physical experiments, for example Refs. 43–45 Physical obstructions used as a barrier have been implemented to retain a planar sloshing pattern, for example rigid and flexible baffles in the horizontal and vertical planes, floating roofs and mats. The effects of rigid and flexible baffles on the tank response had been investigated theoretically and experimentally, for example Refs.…”

Seismic fragility assessment of building-type structures in oil refineries

“…Research to date on the seismic fragility of oil refinery structures is unevenly distributed among them. While liquid storage tanks (e.g., Bakalis et al 2017;Spritzer and Guzey 2017;Vathi et al 2017;Phan et al 2020;Bakalis and Karamanos 2021;Caprinozzi and Dolšek 2021;Hernandez-Hernandez et al 2021;Yu and Whittaker 2021), pipe-racks (e.g., Bursi et al 2018;Di Sarno and Karagiannakis 2020;Farhan and Bousias 2020;Zhang et al 2021) and pressure vessels (e.g., Patkas and Karamanos 2007;Karakostas et al 2015;Fiore et al 2018) are considered well-studied, flare stacks, chimneys (e.g. Guo and Zhang 2019), piping systems within plants (Bursi et al 2015;Di Sarno and Karagiannakis 2020) and open-frame structures (e.g., Butenweg et al 2021) have received comparatively little attention.…”