Shake table investigation of nonlinear soil–structure–fluid interaction of a thin-walled storage tank under earthquake load

Advances in Structural Engineering

2022

In conventional seismic design, bridges usually are assumed to be fixed to a rigid support. This assumption, however, does not correspond to the reality of bridges with shallow footings since they can rock in strong earthquakes. It has been recognised that several factors significantly affect the response of bridges with rocking footings, including support flexibility, pier height and pounding. Most studies so far have mainly focused on a single factor. This research aims to narrow the knowledge gap by investigating the combined effect of pier height, support condition and earthquake characteristics on bridges with rocking ability. A series of shake table experiments on a single-frame bridge with different pier heights and support conditions under hard, medium and soft soil excitations were carried out. The influence of support flexibility was examined by comparing the response of rocking bridges on rigid support with that on soil support. The result shows that regardless of the flexibility of the support, in the case of no pounding, it is beneficial to take rocking footing into account because the maximum bending moment at the pier support can be reduced. However, when pounding was considered, the combined effect can generate an even larger maximum bending moment than that of the fixed-base bridge.

Section: Introductionmentioning

confidence: 87%

Effect of pier height and support flexibility on seismic response of bridges including poundings

Yang

Meng

Advances in Structural Engineering

2022

“…In contrast to the vast number of numerical studies in the literature, limited experimental research has been reported considering the effects of SSI on tank response. Hernandez-Hernandez-Hernandez et al [13][14][15][16][17][18] experimentally explored the simultaneous effects of uplift and SSI on a tank-water system response. It was found that for tanks with an aspect ratio ℎ∕𝑟 ≥ 2, uplift is more likely to be experienced with increasing stiffness of the supporting medium.…”

Section: Introductionmentioning

confidence: 99%

“…The results were presented in radar plots that revealed the dependency of the tank response on the aspect ratio. 17 Kirtas et al 19 reported experimental and theoretical results from an instrumented steel water tank of 28.5 m diameter under 74 low intensity earthquakes. The study focused on the effects of the flexible supporting base on the natural frequencies of the soil-tankwater system.…”

Section: Introductionmentioning

confidence: 99%

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

Hernandez‐Hernandez

Larkin

Earthq Engng Struct Dyn

2022

Self Cite

Aboveground liquid storage tanks are often found on weak compressive soil due to their proximity to harbours and rivers. These soil conditions lead to a high probability of significant soil‐structure interaction (SSI) under earthquake loading. In strong earthquakes, the transient partial separation of the tank base from the supporting medium (uplift) and chaotic liquid sloshing often cause damage to the tank wall. This experimental research determines the simultaneous effects of SSI and the restriction of sloshing on the development of hoop and axial stresses in the tank wall. A low‐density polyethylene tank with two different supporting foundation conditions, that is rigid and flexible, was tested using a shake table. A high‐density foam floating lid was utilised as a barrier to the development of sloshing enabling evaluation of the contribution of sloshing to wall stress development. The maximum experimentally determined stresses are compared with those from a nonlinear elastic spring‐mass model. The results reveal that a flexible supporting medium reduces the development of stresses by increasing the occurrence of uplift compared to that when the tank lies on a rigid supporting medium. Furthermore, restricting chaotic sloshing decreases both the maximum stress and uplift. The spring‐mass model predicts the maximum stresses with more accuracy when the tank is on a flexible than on a rigid supporting medium.

“…The characteristics of the seismic excitation, for example, frequency content, amplitude, and duration 13–16 The interaction between the soil and tank (soil‐structure interaction SSI) 17–20 …”

Section: Introductionmentioning

confidence: 99%

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

Hernandez‐Hernandez

Larkin

Earthq Engng Struct Dyn

2021

Self Cite

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.