Soil-structure Interaction Problems Research Articles

Reduced order modeling of non-linear monopile dynamics via an AE-LSTM scheme

Non-linear analysis is of increasing importance in wind energy engineering as a result of their exposure in extreme conditions and the ever-increasing size and slenderness of wind turbines. Whilst modern computing capabilities facilitate execution of complex analyses, certain applications which require multiple or real-time analyses remain a challenge, motivating adoption of accelerated computing schemes, such as reduced order modelling (ROM) methods. Soil structure interaction (SSI) simulations fall in this class of problems, with the non-linear restoring force significantly affecting the dynamic behaviour of the turbine. In this work, we propose a ROM approach to the SSI problem using a recently developed ROM methodology. We exploit a data-driven non-linear ROM methodology coupling an autoencoder with long short-term memory (LSTM) neural networks. The ROM is trained to emulate a steel monopile foundation constrained by non-linear soil and subject to forces and moments at the top of the foundation, which represent the equivalent loading of an operating turbine under wind and wave forcing. The ROM well approximates the time domain and frequency domain response of the Full Order Model (FOM) over a range of different wind and wave loading regimes, whilst reducing the computational toll by a factor of 300. We further propose an error metric for capturing isolated failure instances of the ROM.

Material damping in a stratified soil deposit

Due to the extensive use of one-dimensional equivalent linear analyses to determine the free-field response of nonlinear soil deposits, dynamic numerical simulations able to reproduce an analogous response to equivalent linear codes are of great value for practical engineering, particularly for dynamic soil-structure interaction problems. An appealing alternative, for problems not close to a failure condition, is to assume a linear elastic behaviour of the soil but with stiffness parameters derived from one-dimensional equivalent linear analyses, i.e. consistent with the level of deformation induced by the input motion. In this approach, energy dissipation has to be artificially incorporated through material damping formulations. In this work, local, Rayleigh, and hysteretic damping formulations in FLAC were assessed to emulate results from one-dimensional equivalent linear analysis. A main feature of the analyses is that they consider a site having a considerably stratified soil deposit, in which the shear wave velocity profile displays significant variations and where the selection of some parameters in the damping formulations is not a trivial task. Results provide relevant insights into the performance of the adopted damping formulations and the selection of material damping parameters to reproduce results of equivalent linear analyses.

Centrifuge investigation of soil–foundation–superstructure interaction under static loading

Extensive efforts have been made to investigate soil–structure interaction (SSI) through numerical simulations whereas little experimental research is reported that tests the applicability of existing numerical models to SSI problems. To provide such experimental data, a unique series of experiments with 3D-printed aluminium framed structures supported by isolated spread footings were conducted in a geotechnical centrifuge. The centrifuge models included equipment and instrumentation that allowed the application of a uniformly distributed static load to the structures as well as the measurement of column loads and foundation movements. The effect of the stiffness of the structure relative to that of the soil was evaluated by varying the number of storeys in the structures and the type/relative density of foundation soils. The variability of soil properties was also studied by modifying the support conditions at single columns at various plan locations of the structure. It is shown that there is appreciable load redistribution in the superstructure, the amount of which depends primarily on the relative structure–soil stiffness and the location of weak and/or rigid foundations. The comparison between the centrifuge test results and the predictions from a simple numerical model with the footings simulated by appropriate linear elastic springs indicates that such a simple numerical model can provide a reasonable prediction of SSI.

The Effect of Soil-Structure Interaction on the Seismic Response of Structures Using Machine Learning, Finite Element Modeling and ASCE 7-16 Methods.

Seismic design of structures taking into account the soil-structure interaction (SSI) methods is considered to be more efficient, cost effective, and safer then fixed-base designs, in most cases. Finite element methods that use direct equations to solve SSI problems are very popular, but the prices of the software are very high, and the analysis time is very long. Even though some low-cost and efficient software are available, the structures are mostly analyzed for the superstructure only, without using the geotechnical properties of the ground and its interaction effects. The reason is that a limited number of researchers have the knowledge of both geotechnical and structural engineering to model accurately the coupled soil-structure system. However, a cost-effective, less time-consuming and easy-to-implement technique is to analyze the structure along with ground properties using machine learning methods. The database techniques using machine learning are robust and provide reliable results. Thus, in this study, machine learning techniques, such as artificial neural networks and support vector machines are used to investigate the effect of soil-structure interactions on the seismic response of structures for different earthquake scenarios. Four frame structures are investigated by varying the soil and seismic properties. In addition, varying sample sizes and different optimization algorithms are used to obtain the best machine learning framework. The input parameters contain both soil and seismic properties, while the outputs consist of three engineering demand parameters. The network is trained using three and five-story buildings and tested on a three-story building with mass irregularity and a four-story building. Furthermore, the proposed method is compared with the dynamic responses obtained using fixed-base and ASCE 7-16 SSI methods. The proposed machine learning method showed better results compared with fixed-base and ASCE 7-16 methods with the nonlinear time history analysis results as a reference.

Soil-structure interaction: A state-of-the-art review of modeling techniques and studies on seismic response of building structures

The present article aims to provide an overview of the consequences of dynamic soil-structure interaction (SSI) on building structures and the available modelling techniques to resolve SSI problems. The role of SSI has been traditionally considered beneficial to the response of structures. However, contemporary studies and evidence from past earthquakes showed detrimental effects of SSI in certain conditions. An overview of the related investigations and findings is presented and discussed in this article. Additionally, the main approaches to evaluate seismic soil-structure interaction problems with the commonly used modelling techniques and computational methods are highlighted. The strength, limitations, and application cases of each model are also discussed and compared. Moreover, the role of SSI in various design codes and global guidelines is summarized. Finally, the advancements and recent findings on the SSI effects on the seismic response of buildings with different structural systems and foundation types are presented. In addition, with the aim of helping new researchers to improve previous findings, the research gaps and future research tendencies in the SSI field are pointed out.

Numerically study of SSSI effect on nuclear power plant on layered soil

In typical dynamic soil-structure interaction (SSI) problems, the dynamic response a structure can be affected by the existence of some nearby structures, which is sometimes referred to as the dynamic structure-soil-structure interaction (SSSI). This effect is especially important in the earthquake engineering design of adjacent nuclear power plants, as the safety risk is relatively high. However, the current understanding on the SSSI of nuclear power plants is still insufficient. In this work, we use the finite element method to investigate the SSSI of two nuclear power plants located at a specific distance under earthquake excitation. Four nuclear-power-plant-soil systems are designed to account for the SSI and SSSI respectively, where the soil properties are obtained from drilling data. The effect of the SSSI on the nuclear power plants is studied by comparing the dynamic responses of four nuclear power plants-soil systems in vertical and horizontal directions, in which both layered soils and local weak interlayer soils are considered. The results of numerical study show that the presence of one nuclear power plant has a favorable effect on the seismic response of an adjacent nuclear power plant, such as reducing the displacement response, but this effect is limited. In addition, the SSSI effect is related to not only the soil properties, but also the direction of ground motion. Furthermore, the existence of soft soil layers complicates the SSSI effect. The results provide important insights for the construction and expansion of nuclear power plants.

A probabilistic study on impedances and kinematic response factors of square pile groups in homogeneous soils

The complexity of the Soil-Structure Interaction (SSI) problem is mainly due to difficulties related to the modelling of the soil-foundation behaviour, which is not only frequency-dependent, but is also largely influenced by uncertainties related to soil properties and stratigraphic conditions. According to a sub-structuring scheme for the analysis of SSI problems, a deterministic approach is usually adopted for the analysis of the soil-foundation system assuming properties and geotechnical models based on the expert judgment, despite the fact that uncertainties related to the intrinsic variability of soil parameters are widely recognised and confirmed by experimental campaigns and laboratory tests.This paper presents a probabilistic study on the dynamic behaviour of square pile group foundations in homogeneous soils, focusing on the effects of the uncertainties related to (i) the frequency-dependent impedance functions and (ii) the kinematic response factors. Above quantities are required to define compliant restraints for the modelling of the soil-foundation system in performing inertial soil-structure interaction analysis, and for the definition of the foundation input motion starting from the free-field motion. Square pile groups are considered, and uncertainties are described through probabilistic distributions of parameters governing the soil-foundation dynamic response. The probabilistic analyses are performed through a numerical model developed by the Authors and some results are presented to show and discuss the variability of the results. In addition, a sensitivity analysis is performed to assess the influence of each variable uncertainty on the system response. Overall, response quantities are found to be very sensitive to shear wave velocity, although soil density and pile elastic modulus may often play a significant role.

A State of The Art Review on Soil-Structure Interaction and Seismic Protection System of Nuclear Power Plant

Soil-structure interaction (SSI) is conventionally considered to be advantageous to the seismic response of a structure. Designers proposed that the least consideration of SSI in structural design results in conservative design. Indian Standard codes allow seismic coefficient ignorance or total reduction of SSI. However, advancements made in developing methods by adding SSI in design to avoid the SSI problem becomes a rarity. This paper summarizes several guidelines and techniques related to SSI analysis of structures. Seismic protection systems (SPS) are successfully installed in conventional designs, but most of the nuclear power plants (NPPs) are not equipped with SPS. Besides, considerable research was carried out to comprise SPS in nuclear power plant design. Currently, horizontal isolation is provided in for structures in active seismic zones. This may be insufficient and vertical isolation has also been required. The results of this review indicated that the future construction of nuclear plants in seismic zones should be equipped with advanced SPS to fulfill the standardised design.

Numerical Modeling of a Pile Group Subjected to Seismic Loading Using the Hypoplasticity Model

Various simple and complicated models have been utilized to simulate the stress-strain behavior of the soil. These models are used in Finite Element Modeling (FEM) for geotechnical engineering applications and analysis of dynamic soil-structure interaction problems. These models either can't adequately describe some features, such as the strain-softening of dense sand, or they require several parameters that are difficult to gather by conventional laboratory testing. Furthermore, soils are not completely linearly elastic and perfectly plastic for the whole range of loads. Soil behavior is quite difficult to comprehend and exhibits a variety of behaviors under various circumstances. As a result, a more realistic constitutive model is needed, one that can represent the key aspects of soil behavior using simple parameters. In this regard, the powerful hypoplasticity model is suggested in this paper. It is classified as a non-linear model in which the stress increment is stated in a tonsorial form as a function of strain increment, actual stress, and void ratio. Eight material characteristics are needed for the hypoplastic model. The hypoplastic model has a unique way to keep the state variables and material parameters separated. Because of this property, the model can implement the behavior of soil under a variety of stresses and densities while using the same set of material properties.

The Ultimate Load of the Fiber-Reinforced Concrete Slab Foundations Subjected the Concentrated Load by ANSYS

In practice, the slab foundation is used widely in civil engineering. Besides the concrete material, fiber concrete is applied more popular in the slab foundations. Determining the ultimate load of the slab foundations is a complex problem due to the relation of the soil-structure interaction (SSI) problem, which depends on both the structures and the subsoil characteristics. ANSYS is a finite element software which is a reliable and effective technique to simulate the structure model. This paper aims to determine the ultimate load of the fiber-reinforced concrete slab on the ground subjected to the concentrated load by ANSYS software. The nonlinear material of the structure and the subsoil will be considered in this work. The validation test of the numerical model will be through the experiment data. This study has shown that the numerical model is reliable for the structure design.

Investigation of Small-Scaled Soil Structure Model under Earthquake Loads via Small Shaking Table Tests

This paper aims to determine the appropriate scaling coefficient rigorously in the dynamic analysis of structures via small shaking table tests to represent the full real case while considering the soil-structure interaction problem. In addition, we investigate the seismic effects of the superstructure with flexible and fixed bases. To achieve this purpose, seven stories of concrete moment-resisting frames supported on silty clay soil were scaled. According to the shaking table specifications, a small-scaled soil-structure model was executed with a scaled factor of 1 : 50. Consequently, the scale steel skeleton model was built to represent the real superstructure. In addition, the laminar soil container for the soil block was constructed to reduce undesirable boundary effects. Three earthquakes have been applied at the superstructure base as a fixed base and at the bottom of the soil block in the soil structure system as a flexible base. The numerical simulations are implemented for scaled and real models. According to obtained results from experimental and numerical investigations, the numerical model achieved good results with experimental observation. In addition, the small scaling factor of 1 : 50 can represent the seismic response of full construction conditions with acceptable precision. It is observed that the flexible base has overestimated in lateral displacement of the real superstructure compared with a fixed base, in which the maximum amplification percentage at the roof floor level reaches up to 98% under seismic load. Otherwise, the shear force distribution along the height and base shear of the superstructure with a flexible base decreases compared with a fixed base. The maximum reduction percentage is 38% under seismic load. Consequently, the safety and cost of the superstructure are affected.

Coupling spectral and Finite Element methods for 3D physic-based seismic analysis from fault to structure: Application to the Cadarache site in France

This paper presents the application of a coupling strategy between the Spectral (SEM) and Finite Element (FEM) Methods to solve the soil-structure interaction (SSI) problem. The SEM-FEM coupling benefits from the mesh refinement capabilities of the FEM in modeling the structure and the near soil, with the realism of the SEM for regional scale earthquake simulations from the fault to the site. To this end, the Domain Reduction Method (DRM) introduced by (Bielak et al., 2003) is herein employed. The DRM formulation solves the problem of multi-scale earthquake simulations by subdividing the fault-to-structure problem into two simpler ones, namely: problem I- containing the structure and (hereafter solved using the FEM) and problem II- containing the fault, the regional geological and surface topography, the sedimentary basin (hereafter solved using the SEM). In this work, the coupling between the FEM code CAST3M and the SEM code SEM3D is presented, verified and compared to conventional one-dimensional (1D) deconvolution methods for SSI analysis. A seismic simulation is performed, considering a simplified virtual nuclear reactor building, artificially positioned on the Cadarache site in South-Eastern France. The applicability of the SEM3D-CAST3M coupling is demonstrated, for SSI analysis in linear elastic regime and with a 50 % reduction of the model dimensions. Moreover, the coupling captures the amplified response for the nuclear structure due to the 3D spatially variable input field and to the resulting surface wave propagation in the SEM-FEM SSI analysis.

Analytical Solutions for Ultimate Stabilizing Action of Anchored Piles in Cohesive Soil Layers

The design of slope-stabilizing piles is still an open issue for civil engineers, owing to the high number of variables to be determined in the design process and to the complexity of soil–structure interaction problems. In this paper, in the simplified case of subhorizontal cohesive soil strata, analytical solutions are proposed for the maximum available stabilizing action for a pile, also considering the possible presence of an anchor at the pile’s head, and thus extending some results already available in literature. Within the framework of an ultimate limit state approach, the influence of soil mechanical properties, of pile characteristics, and of the anchor strength are investigated, and some dimensionless abaci are analytically derived. The solutions demonstrate a marked coupling effect between tensile anchor strength and pile-bending resistance, and an explicit optimization strategy for a safe and effective dimensioning is provided. The results can be profitably employed in the most common limit equilibrium methods for slope stability analysis.

A Simple Breakage Model for Calcareous Sand and Its FE Implementation

This paper reports the development of a particle breakage model within a finite-element (FE) framework based on the modified Mohr–Coulomb model (MMC). A modified form of the strength-dilatancy relationship is used to incorporate additional energy consumed due to particle breakage. A new particle breakage index is introduced and constitutively linked to the mobilized friction angle. The model is verified against carefully conducted drained triaxial tests on medium-dense calcareous sand obtained from offshore Australia as well as other published data. The model is implemented in the FE program ABAQUS for both small strain and large deformation FE analyses in practical field problems. Several important microscopic observations can be made from the proposed model that are not limited to identifying soil regions where particle breakage is maximized. Due to its inherent simplicity, the newly developed model can provide reasonable predictions for soil-structure interaction problems in calcareous sands.

Field tests and numerical analysis of the effects of scour on a full-scale soil–foundation–structural system

Scour is the prevailing cause of bridge failure worldwide, leading not only to traffic disruption, but also to social and economic losses and even to casualties. Many vibration-based monitoring techniques have been proposed for identifying the scour location and extent, based on the evaluation of the changes of the bridge modal properties due to scour. This study describes the experimental and numerical research carried out to investigate the effects of scour on the dynamic properties of structures with shallow foundations. Although these are the most vulnerable ones, they have received less attention compared to structures founded on pile foundations. To fill some existing knowledge gaps, field experiments were carried out on EuroProteas, a structural prototype with shallow foundation that was subjected to increasing levels of scour. The changes of the dynamic properties of the system are evaluated by postprocessing the ambient vibration recordings and by developing various models of the soil–foundation–structural system with different descriptions of the soil–structure interaction problem. The study results shed light on the effects of scour on systems with shallow foundations and on the accuracy of alternative modelling approaches. They are presented here to inform the development and validation of vibration-based techniques and modelling strategies for bridge scour identification.

Sürdürülebilir Beton ve Zemin Dolgulu Sürekli Temellerin Monoton Yükler Altındaki Davranışı

Due to the renovation of structures, natural disasters, and regional-global wars, construction and demolition waste material is generated. The remediation of these wastes by recycling and reusing activities is one of recent most common research topics. Recycled aggregates are obtained through the recycling activities of these waste materials. In the literature, detailed studies have been carried out to use recycled aggregate as a sustainable product in producing new concrete or as a filling material. Besides, the scope of these studies continues to expand. In this comprehensive study, the structural behavior of the soil-structure interaction problem under the monotonic load, which is assumed to be produced with sustainable materials, was investigated. Furthermore, the concrete properties of these foundation beams representing the superstructure were considered with conventional and sustainable concrete. The characteristics of the filling materials were regarded with five different sustainable materials. The deflection, rotation, bending moment, shear force, and spring forces are obtained based on the numerical simulation. The sustainable soil-structure interaction problem results were compared with the conventional counterparts. Based on the comparisons, it was observed that the deflection, rotation, bending moment, shear force, and spring forces that occur in the foundation beam are affected by sustainable material properties.

Influences of Wall Configurations on Earthquake Behavior of Cantilever Retaining Walls Considering Soil-Structure Interaction Effects

Cantilever walls are frequently and necessarily built not only in earthquake prone regions but also on different foundation subsoils with various physical and mechanical characteristics. The response of these structures is a complicated soil-structure interaction (SSI) problem, in which the relative stiffness between the soil and structure is of critical importance. In addition to different soil conditions and earthquake motions, the wall configurations have an important role in the cantilever retaining wall design. Thus, the major objective of this work is to investigate the effects of various configurations on seismic response of the cantilever retaining walls considering SSI. Accordingly, the seismic response of the interaction systems is revealed using the 3D finite element models (FEM) in time domain, assuming linearly elastic behavior for the wall, and elastoplastic behavior for backfill and foundation soil. Viscous absorbent boundaries are employed to both simulate radiation scenario and avoid undesirable wave reflections generated by soil lateral boundaries. Backfill-wall interfaces are modeled using the unidirectional interface elements with nonlinear force-deflection abilities. The interaction systems are analyzed considering three different cantilever wall configurations (inverted T-type, L-type, and the wall with a base key), four different ground motion records, and four different subsoil systems. Nonlinear seismic analyses are carried out to visit how considering the variation of these parameters influences the wall behavior. The results from parametric studies show that the wall configuration, SSI effects and ground motions are remarkably influential on seismic responses of the cantilever walls such as the stresses and horizontal displacements.

Twin earth pressure balance tunnelling – monitoring and numerical study of an urban case

In recent decades, numerical calculations have often been used to optimise, from a technical and economical perspective, the design of underground works. Using these tools allows efficient and affordable designs to be obtained. Simulation of the tunnelling procedure when using a tunnel-boring machine and in urban areas is a complex soil–structure interaction problem. Here, a three-dimensional (3D) code using finite differences is used. The reference case of this study is Lyon metro line D project in France, where a non-symmetric load is present at the surface due to the presence of a retaining wall. An accurate on-site monitoring system was set up to assess ground movements during the mechanised excavation of twin tunnels. The collected data are used as a reference to show the validity and accuracy of the developed 3D model. Two constitutive models were used to simulate the soil behaviour: plastic hardening (PH) and linear elasticity with perfect plasticity (Mohr–Coulomb shear failure criterion). The Mohr–Coulomb constitutive model shows some drawbacks, which can be eliminated by using PH. The existence of a retaining wall induces a non-symmetric load condition; however, the settlement trough predicted by advanced numerical models shows good agreement with that obtained by monitoring data.

Extension of 3-D coupled DDA-SPH method for dynamic analysis of soil-structure interaction problems

Soil-structure interaction problems are an important issue in the research field of geotechnical engineering. Understanding and modeling the soil-structure interaction problems is thus critical. Such interaction problems involve the mechanical behaviors of both soil and structure as well as their complex interaction. Discontinuous deformation method (DDA) is appropriate for modeling mechanical behavior of structure, while smoothed particle hydrodynamics (SPH) offers a feasible technique for describing the mechanical behavior of soil material. A coupled DDA-SPH method can integrate the advantages of both DDA and SPH. For three-dimensional (3-D) dynamic analysis of the soil-structure interaction problems, the original 3-D coupled DDA-SPH method must be extended, which is the primary purpose of this paper. In the extended 3-D coupled DDA-SPH method, an elastic-plastic soil constitutive model associated with the Drucker-Prager yield criterion is implemented. The interaction between soil and structure is realized through a newly proposed coupling scheme based on a penalty method using the Mohr-Coulomb failure criterion. Furthermore, the extended 3-D coupled DDA-SPH method is validated through the investigation of four experiments. The simulation results suggest that the extended 3-D coupled DDA-SPH method can accurately simulate the large deformations and post-failure behavior of soil-structure interaction problems.

Three‐dimensional nonlinear soil–structure interaction for Rayleigh wave incidence in layered soils

AbstractWe propose a methodology to analyze three‐dimensional (3D) nonlinear soil–structure interaction (SSI) problems for Rayleigh (R) wave incidence in horizontally layered soils. The methodology comprises of two steps: (i) we calculate the free‐field displacement histories of the layered soil subjected to incident R wave using thin‐layer method (TLM) and (ii) we compute the effective input forces using domain reduction method (DRM) and simulate the responses of the structure and its vicinity using finite element analysis. Through a comprehensive verification study, we find good agreement with published research on SSI problems that implement boundary elements in the free‐field; as well as on layered media problems with no structures that implement the propagator matrix technique and TLM. The agreement is consistently good for homogeneous and layered soils in 2D and 3D. Finally, we illustrate the capability of the methodology through a nonlinear analysis of a 12‐story building on a two‐layer soil overlaying a homogeneous halfspace, subjected to R wave incidence. The presented example highlights the influence of incident wave azimuth on measures of the building response, such as peak acceleration, inter‐story drift ratio, and rocking motions.