Water Structure Interaction Research Articles

Application of material point method in modeling soil-geosynthetics interactions-a literature survey

The material point method (MPM) has garnered significant attention in recent years owing to its advantages in solving soil–water-structure interaction problems involving large deformations in geotechnical engineering. The MPM combines the benefits of point-based and mesh-based approaches (finite element method) with both Eulerian computational mesh and continuum descriptions of materials. The successful integration of MPM in simulated landslides, internal erosion, and excavation has been frequently reported. However, solving the soil–geosynthetic interaction problem with the MPM has not been explored, although such problems often entail large deformations. The goal of this study is to collate studies on the simulation of geosynthetics and their interactions with soil using MPM. This paper first discusses the basics of MPM and the formation of thin membrane materials using MPM. It also includes limited applications of MPM in simulating soil–geosynthetic interactions. The applications demonstrate that the MPM is particularly effective in resolving large deformation problems associated with geosynthetics, including problems of landfill settlement, reinforced-slope stability, and geocontainer dropping.

ANN deformation prediction model for deep foundation pit with considering the influence of rainfall

Deep foundation pits involving complex soil–water-structure interactions are often at a high risk of failure under heavy rainfall. Predicted deformation is an important index for early risk warning. In the study, an ANN model is proposed based on the Wave Transform (WT), Copula method, Convolutional Neural Network (CNN) and Long Short-Term Memory Neural Network (LSTM). The total deformation was firstly decomposed into low and high frequency components with WT. The CNN and LSTM were then used for prediction of the two components with rolling training and prediction. The input variables of the CNN and LSTM were determined and optimized based on the correlations analysis of Copula method of the two components with different random variables, especially with the rainfall. And finally, the predicted total deformation was obtained by adding the two prediction components. A deep foundation pit in Chengdu, China was taken as a case study, of which the horizontal deformation curves at different measuring points shows three types of developed trend, as unstable, less stable, and stable types. The predictions of the deformations of different development types by the proposed ANN model show high accuracies with a few input variables and can accurately prompt risk warning in advance.

Used Isolation System to Reduce the Response of Offshore Structure Considering Soil Structure Interaction

Abstract Fixed offshore platforms are structures of steel or concrete located in the middle of the sea used to export oil, trade, or military. These are designed to withstand all types of weather and dynamic loads. The response was very high under applied these loads. This paper includes a proposal to apply a new isolation system to be placed in different places on the offshore platform to reduce vibrations from high water waves. Three cases that be used, fixed-based (column connect directly to the pile), isolation system in the pile head (isolation between column and pile), and isolation system in the pile head and the middle of columns. The dynamic movements in waves were simulated using ABAQUS programs. More accurate elements and real material properties were used to bring the results closer to reality. The Computational Fluid Dynamics (CFD) method was used to study the effect of water-structure interaction and soil-structure interaction. The results show that the use of the isolation system at the base of the offshore platform has a very significant effect on decreasing the response of the platform to the loads placed on it. Where the isolation system works as a hinge at the pile head and is not allowed to move and rotate for the pile, also the moments are zero. As for the shear force, it is the least that can be compared with the other cases.

Underwater shaking table tests of a sea-crossing cable-stayed bridge under combined earthquake and wave action

Sea-crossing cable-stayed bridges may encounter the combined effects of earthquakes, waves, and currents, seriously threatening their service safety. In this paper, the effects of the combined earthquake and wave action on the dynamic responses of a sea-crossing cable-stayed bridge are investigated through underwater shaking table tests. The coordinative similitude law is adopted to fulfil the similarity of hydrodynamic and wave force. The test results indicate that, the combined action of earthquake and wave has significant effects on the dynamic response of the bridge tower, while the effects vary with the height of the tower and the type of ground motion. The side pier exhibits greater dynamic responses at the same loading cases and is more susceptible to the combined earthquake and wave action than the auxiliary pier. On the whole, in comparison to earthquake excitation alone, the combined earthquake and wave action significantly enhances the dynamic responses of sea-crossing cable-stayed bridge in most cases, with a maximum magnitude up to 20%–30%. By comparing with previously conducted underwater shaking table tests of substructures, the effects of water-structure interaction on the full cable-stayed bridge and bridge tower foundation are close, both of which are obviously lower than the effects on bridge pier.

Dynamic response of OWTs under wind-wave loads considering 3D water-pile-soil interactions

A new three-dimensional (3D) integrated model of offshore wind turbine (OWT) is proposed, which considers the soil-monopile-water interactions and the accumulative deformation of foundations under cyclic loads. The effects of three different modelling methods on the dynamic response of wind turbine are discussed, where three modelling methods are the new WOT model, OWT model with a 3D soil-pile medium without a seawater domain and OWT model with API's spring-type foundation. The numerical results show that the use of API's soil spring may overestimate the fundamental frequency of OWT by up to 32.2%. This leads to inaccurate structural resonance. Meanwhile, a significant displacement drift of the tower top of the new model is observed due to the ratcheting effect, and the OWT with API's spring cannot correct this phenomenon. Consequently, the API method should be used with care in assessing dynamic performance under wind-wave loads. The added mass method considers only the water-structure interaction and excludes the soil-water interaction, and it may underestimate the responses of the tower, blades and monopile, which can render the design of wind turbines unsafe. Additionally, assumption of the parked condition underestimates the structural response, and the frequency of the blades may change during operation.

Study on the hydrodynamic added mass of rectangular pier under sine wave actions

As for deep-water bridges in river, sea, and reservoirs, the water-structure interaction is non-negligible when investigating its seismic performance. Morison equation and radiation wave theory are two main methods for calculation of hydrodynamic pressure resulted from water-structure interaction, which cannot truly simulate the complicated interaction between water and structures. This study conducts a series of underwater shaking table tests on seven rectangular steel tubes to predict the hydrodynamic added mass of rectangular piers considering water-pier interaction. The influence of action amplitude, action frequency, water depth, depth of cross section, and width of upstream face of the pier on hydrodynamic added mass is investigated. The results show that the hydrodynamic added mass of pier first decreases and then increases with action frequencies. The hydrodynamic added mass is proportional to a-th (a > 1) power of water depth due to the influence of structures on the movement of water. The hydrodynamic added mass increases with depth of cross section and width of upstream face of pier, and changes slightly with the action amplitude with maximum percentage of 10% and thus can be neglected. Therefore, except for the water depth, depth of cross section, and width of upstream face, the frequency characteristics of ground motions should be considered when analyzing the water-pier interaction under earthquake actions.

Seismic Analysis of Steel Tanks Subjected to Transitional-Rotational Components of Earthquakes

ABSTRACT In this study, the response of the steel water storage tank considering the water-structure interaction under the effects of the transitional and rotational components of the earthquake as well as the soil-structure interaction was evaluated using the Eulerian-Lagrangian method. Seismic loading consisted of rotational and transitional components of the earthquake. Rotational components of the earthquake were first obtained using the transitional components. Then, the seismic analysis of the tanks considering four different tank models with empty and 90% full reservoirs and five different foundation models with and without considering the rotational components was done. Foundation flexibility and its effect on the structure performance were addressed by changing the foundation stiffness from the rigid to the very soft one. Water-structure interaction was considered in the analysis taking into account the fluid compressibility and the energy absorption boundaries. Results showed that in most cases by applying the rotational components, the maximum displacements and shear stress decreased. Maximum displacement reduction values for tanks with height to radius ratios of 0.4, 1, 2, and 3 for empty tanks are 51.62, 32.32, 24.0, and 23.79, respectively, and tanks with 90% full are 49.42, 42.86, 28.88, 26.74, respectively. Also, principle stress decreased in most cases, and in few cases, an increase was observed. This decrease in shear stress was far higher for empty reservoirs than full reservoirs. By increasing the tank height, reducing effects of the rotational components in the seismic response of the tanks reduced, and the structural responses with and without applying the rotational components got close to each other. Results also showed that the rotational components have a significant effect on the structural response in terms of changing the location of the maximum responses in whole cases as well as increasing the maximum response in a few cases.

CFD Simulation of a Submersible Passive Rotor at a Pipe Outlet under Time-Varying Water Jet Flux

During the past two decades, passive rotors have been proposed and introduced to be used in a number of different water sector applications. One of these applications is the use of a passive rotor at the outlets of pipe outfalls to enhance mixing. The main objective of this study is to develop a CFD computational workflow to numerically examine the feasibility of using a passive rotor downstream of the outlet of pipe outfalls to improve the mixing properties of the near flow field. The numerical simulation for a pipe outlet with a passive rotor is a numerical challenge because of the nonlinear water-structure interactions between the water flow and the rotor. This study utilizes a computational workflow based on the ANSYS FLUENT to simulate that water-structure interaction to estimate the variation in time of the angular speed (ω) of a passive rotor initially at rest and then subjected to time-varying water velocity (υ). Two computational techniques were investigated: the six-degrees-of-freedom (6DOF) and the sliding mesh (SM). The 6DOF method was applied first to obtain a mathematical relation of ω as a function of the water velocity (υ). The SM technique was used next (based on the deduced ω-υ relation by the 6DOF) to minimize the calculation time considerably. The study has shown that the 6DOF technique accurately determines both maximum and temporal angular speeds, with discrepancies within 3% of the measured values. A number of numerical runs were conducted to investigate the effect of the gap distance between the passive rotor and the pipe outlet and to examine the effect of using the passive rotor on the near flow field downstream of the rotor. The model results showed that as the gap distance of the pipe outlet to the passive rotor increases, the rotor’s maximum angular speed decreases following a decline power-law trend. The numerical model results also revealed that the passive rotor creates a spiral motion that extends downstream to about 15 times the pipe outlet diameter. The passive rotor significantly increases the turbulence intensity by more than 500% in the near field zone of the pipe outlet; however, this effect rapidly vanishes after four times the pipe diameter.

Water–structure interaction analysis of a segmental bridge using ambient vibration testing at different water levels

Updating a finite-element (FE) model using dynamic parameters obtained from field testing requires an adequate understanding of the variation of such parameters due to changes in environmental conditions. This paper presents an experimental program to study the influence of the water–structure interaction in the dynamic response of a prestressed concrete segmental bridge with partially submerged piers in an artificial reservoir. The bridge, located in Colombia, has a total length of 558 m. Ambient Vibration Tests (AVTs) consisted of four experimental campaigns at different water levels to perform modal identification. In addition, existing empirical formulations accounted for the effect of the hydrodynamic masses concentrated in the piers. This paper shows that updating FE models from identified dynamic properties in partially submerged bridges involves percentage reductions in natural frequencies related to the reservoir's water level. Thus, providing a better insight into the incidence of water–structure interaction on partially submerged bridges' dynamic response. Finally, considerations during dynamic characterization tests are discussed.

An accurate and efficient time-domain numerical model for simulating water-axisymmetric structure subjected to horizontal earthquakes

The seismic response of offshore structures is generally influenced by water-structure interaction. This study focuses on the earthquake-induced hydrodynamic forces on axisymmetric offshore structures. Based on the finite element method, an accurate and efficient time-domain numerical model for simulating water-axisymmetric structures subjected to horizontal earthquakes is developed. First, according to interface boundary condition and using the method of separation of variables, the three-dimensional (3D) wave equation governing the compressible water is transformed into a two-dimensional (2D) governing equation in the vertical and radial directions, where the solution in the circumferential direction is analytical. Secondly, an exact artificial boundary condition (ABC) in frequency domain is developed by using the separation of variables method. Third, a high-accuracy ABC that is local in time but global in space is obtained by applying the temporal localization method. Furthermore, the high-accuracy artificial boundary condition is discretized and coupled with the finite element equation of the near field, leading to a symmetric second-order ordinary differential equations. Finally, the coupled finite element equation for the water-axisymmetric cylinder is presented. The proposed method is used to study the effect of water compressibility on the seismic response of and evaluate the seismic responses of a composite bucket foundation.

Large-scale investigation of wave dampening characteristics of organic, artificial floating islands

The concept of floating vegetation-based islands for the bioremediation of aquatic ecosystems is well known. Less so, their hydrodynamic capabilities regarding the damping performance, positional stability and water-structure interactions. To this end, physical model tests with fully organic, reed-based gabions were carried out in a large-scale facility in this study. The initial, reflected, and transmitted waves were recorded and analyzed regarding transmission and reflection coefficients. A motion tracking system was utilized to allow for an investigation regarding the motion of the artificial floating islands under waves. The results show that the artificial floating islands significantly dampen shorter waves with a wave period of T ≤ 2.25 s. The transmission of the incident waves is reduced by 50% for the smallest wave periods (T = 1.5 s). The incident waves are reflected between 20 and 50% for the same wave period. The incident wave energy is dissipated by up to 85% for the smallest wave height and period (H = 0.10 m, T = 1.5 s). The comparable performance regarding more traditional floating breakwaters is discussed as well as the width of the structure as the key parameter for the layout of artificial floating islands in rivers and still waters regarding the damping performance.

Investigations of air cushion effect on the slamming load acting on trimaran cross deck during water entry

The cross-sectional shape of a trimaran is more complex than that of a monohull and consists of a main hull, side hull, and cross deck. When a trimaran moves downward in a severe sea state, air trapped between the main and side hulls forms a cushion under the cross deck, and this has a significant effect on the slamming pressure on the structure. In this work, laboratory experiments are performed on a scale-model trimaran section to gain deeper insight into the dynamic interactions between hull structure, water, and air and to investigate the effects of the air cushion on slamming loads. The air–water–structure interactions are investigated through particle image velocimetry, the accelerations of the ship section are measured by inertial motion units, and the slamming loads are obtained from pressure sensors. To enhance the influence of the air cushion, two plates are installed, one on each side of the ship section, to restrain the escape of air during the experiments. In addition, to eliminate the influence of the air cushion, numerical simulations of water entry are conducted with air replaced by hydrogen, whose density is much lower. The experimental and numerical results confirm that the air cushion under the cross deck can significantly reduce the slamming pressure.

Seismic analysis and test facilities of deep‐water bridges considering water–structure interaction: A state‐of‐the‐art review

AbstractDeep‐water bridges are susceptible to severe damages under strong earthquakes. Water–structure interaction will considerably affect the dynamic performance of deep‐water bridges. In the past few decades, researchers have conducted extensive studies on the water–structure interaction and dynamic behavior of bridges through theoretical, numerical, and experimental investigations. This paper presents a comprehensive review on the calculation method for earthquake and wave‐induced hydrodynamic forces. The seismic responses of deep‐water bridges under individual or combined excitation of earthquake, wave, and current are discussed to explore the influence of water–structure interaction on the seismic capacity of deep‐water bridges. Finally, the development of testing facilities that can simulate the water–structure interaction is summarized. Particularly, a new multifunctional dual underwater shaking table system built‐in Tianjin University that can simulate multiple‐support excitation and water–structure interaction simultaneously is introduced in detail for the first time.

Water adsorption in ideal and defective UiO-66 structures

We combine experiments and simulations to study the adsorption of water in several UiO-66 frameworks (ideal and defect-containing structures). We propose a new set of charges for the frameworks that accurately provides the water-structure interaction at the molecular level. The new set is suitable for predicting water adsorption in the ideal UiO-66 structure, providing for the first time, good agreement between experimental and calculated isotherms. The proposed procedure for tuning the point charges of the framework to achieve agreement with experiments is universal and can easily be extended to other MOFs. We explore the structural characteristics in terms of adsorption of water and the potential application of these materials to water harvesting from air. Our results show that the number of introduced defects significantly affect water sorption properties, which results in shifting steep water uptake and increasing saturation loading. Additional performed experiments, such as Ar sorption and the use of the QE-TPDA method allow for a broad characterization of structure-containing defects and the impact that these defects exert on the properties of the materials. • Integrated experimental and computational study. • Development of a transferable set of charges for the UiO-66 MOF. • Prediction of the adsorption mechanisms of water in UiO-66 with and without defects. • Water adsorption capacity dependency of UiO-66 with defects. • High performance for water harvesting.

Interaction between Water Wave and Geometrical Structures of Floating Triboelectric Nanogenerators

AbstractAlthough triboelectric nanogenerators (TENGs) are highly efficient and adaptable in harvesting ocean wave energy, the dynamics of floating TENGs in underwater wave stimulations have so far rarely been studied. Herein, the interactions between centimeter‐scaled floating structures and water waves are experimentally revealed. By integrating inertial measurement units into the shells of various floating TENG structures, the primary acceleration data associated with different parameters are obtained. Based on the data of 63 literature reported floating TENGs, a series of experimental parameters are elaborately probed, including shell shape, shell size, weight, barycenter, wave strength/frequency, and wave‐producing methods. Through dynamic calculations, each can offer the kernel data of acceleration and frequency distribution curves, revealing several regularities in water–structure interactions associated with TENGs. These calculations could serve as guidance for the design of the future floating TENGs in blue energy harvesting.

Dynamic interaction analysis of structure-water-soil-rock systems under obliquely incident seismic waves for layered soils

A numerical model for the structure-water-soil (layered)-rock (SWLR) system is proposed in this paper to evaluate the system dynamic response, in which the fluid-solid coupling effect is considered by the interface conditions and the wave radiation effects of far-field domain are simulated by artificial boundary conditions. Moreover, this model covers four prime respects, including the discretization of interface conditions, the absorbing boundary conditions, the equivalent earthquake loading input and the general finite element equation. It can be solved by a standard time integration algorithm such as implicit Newmark's method. Furtherly, the effectiveness of the proposed model is verified by three numerical examples. Apart from these, the dynamic stiffness matrix method (DSM) of fluid and solid adopted in present study to acquire the equivalent earthquake loading effectively accomplishes the oblique incidence of the wave in layered half-space with arbitrary angles. Based on the proposed model, the effects of dynamic water-structure interaction (WSI) and soil-water interaction (SWI) on the seismic responses of offshore structure are investigated, which is conducive to the simplified analysis of dynamic fluid-solid interaction and the design of ocean engineering.

Response and damage evaluation of base-isolated concrete liquid storage tank under seismic excitations

The present study analyzes flexible rectangular concrete base-isolated liquid storage tanks (LSTs) for bi-directional earthquakes. The base-isolated LST is modeled in ABAQUS finite element software. The liquid is modeled by the Equation of State (EoS) with arbitrary Lagrangian-Eulerian (ALE) remeshing algorithm, whereas the hexahedral solid finite elements model LST. Nonlinear time history analysis is performed by considering the LSTs’ material nonlinearity and the nonlinearity produced in LST due to the water-structure interaction. As illustrative examples, different LSTs are considered in the present study with five lead rubber bearing (LRB) isolators each, four at the corners and one at the center. The parameters varied for analysis are the isolators’ effective frequency, peak ground acceleration (PGA), height of water, and aspect ratio of LSTs. The response quantities of interest include Tresca stress, sloshing height, hydrodynamic pressure, overturning moment, and base shear. The numerical study results show that the liquid’s sloshing increases by about 20%–30% at optimum frequency. Still, the forces induced in the tank are considerably reduced. The height of water, and aspect ratio of LSTs significantly influences the response behavior of the isolated tank.

The Behavior of Elevated Water Tanks under Impact Loading

Because of the crucial role of elevated water tanks and their various uses, it is necessary to evaluate their structural behavior under threats to improve the durability performance of such tanks without putting them in jeopardy. In the present research, three open cylindrical concrete water tanks were modeled under an impact load (aerial blast) with the weight of 100 kg TNT explosive charge. The tanks were modeled in 3 forms: slender, middle, and broad (Aspect ratio = 1.28,1 and 0.85). Each tank contained various levels of water (non-water, half water, and full water) to estimate their structural behavior under blast loading. Moreover, the CEL (Coupled Eulerian-Lagrangian) approach was used to simulate water structure interaction in finite element program. For a comprehensive analysis of the structural behavior of water tanks, LRB (Lead rubber bearing) isolator device was also used to observe the effect of isolator under blast loading on elevated water tanks in all models. The results of this study show that the water level leads to stiffness of the structures that cause better performance under blast loading and also the intersection of the shaft and concrete column would be the critical section of this structure under blast loading. It is also concluded that Stress and Strain decrease as the water tanks level increase and stiffen (up to 33 %). Also, it is noticeable that the existence of the isolator has deteriorated the results because of the decreases in the structure’s stiffness and the increase of the displacements.

ANALASIS OF WATER-STRUCTURE-SOIL DYNAMIC INTERACTION UNDER EARTHQUAKES

In this paper, we establish an efficient numerical model of water-structure-soil systems under seismic action based on ABAQUS to analyze the influence of water-structure and water-soil interaction on the response of the structure, soil and water under different water depths. Under the action of horizontal ground motions, the results show that the influence of the water-soil interaction on the response of the system is much less than that of the water-structure interaction, and that the influence on the response of the structure, soil and water is negligible. Under the action of vertical ground motions, the effect of water-structure interaction on system response is much less than that of water-soil interaction, and that the water-structure interaction has little influence on the system response. Therefore, only the water-soil dynamic interaction needs to be considered in theoretical simplification analysis.

State -of -the -Art and Development of Seismic Analysis for Complex Bridges

Due to the complexity of dynamic response characteristics of complex bridges, it is difficult to give uniform regulations to give comprehensive and complete guidance for its seismic analysis. In order to promote the development of seismic analysis of complex bridges, the research status and progress of complex bridge seismic analysis were discussed in detail. Firstly, the characteristics of the commonly used seismic analysis methods for bridges and their applicability to complex bridges were summarized. Secondly, the selection and synthesis methods of far-field and near-field seismic used for bridge seismic analysis were concluded. Meanwhile, the seismic input methods and the most unfavorable input direction of curved bridges were discussed. Then, the anti-seismic analysis model of the main components of bridges were summed up, and the medium-structure interaction (including pile-soil-structure interaction, abutment-soil-structure interaction and water-structure interaction, etc.) were investigated. Finally, on this basis, the unsolved problems and the future development directions in this research field were pointed out. It is concluded that the seismic analysis of complex bridges still has some shortcomings, which needs to be improved and developed.