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The paper examines the seismic response of bridge piers, highlighting the essential role of soil-structure interaction (SSI) in enhancing structural resilience. Utilizing MIDAS and LPile software, the study evaluates SSI's impact on bridge pier performance during seismic events. The study involves modeling and analysis under varying soil conditions using MIDAS software. LPile software calculates soil spring stiffness, enabling realistic SSI simulations in MIDAS models. The key objectives include comparison of bridge on deep foundation by analyzing soil properties' effects on SSI, comparing fixed base and SSI models, and providing practical design insights. The findings show significant differences in seismic performance with SSI. The fundamental period increased by 28%, indicating a more flexible response. Maximum displacements in the bridge deck rose by 25% in both X and Y directions, compared to a fixed base model. Additionally, shear forces and bending moments decreased, underscoring SSI's benefits in reducing seismic demands. This study offers valuable insights into bridge structures' dynamic behavior under seismic loading, emphasizing the importance of SSI in seismic design practices. The results are crucial for developing resilient bridge designs capable of withstanding complex SSI during earthquakes. [ABSTRACT FROM AUTHOR]

Seismic isolation systems are one of the most important modern methods in designing earthquake-resistant buildings. These systems separate the building from the ground using flexible devices, reducing the transmission of seismic motion into the building and thus reducing potential damage. These systems include lead-reinforced rubber bearings (LRB) and sliding bearings such as the Frictional Pendulum Bearing System (FPS). Recent studies have shown the high effectiveness of seismic isolation systems in reducing base shear forces and reducing enterer floor displacement during earthquakes, which improves the safety and security of the building. Seismic isolation systems face several challenges, including the effect of soil-structure interaction (SSI), which can affect the effectiveness of the system, especially in soft soil conditions. Research shows that soil quality plays a high role in system performance, as soft soil requires special designs to achieve the desired performance.In addition, 3D seismic isolation systems have been developed to counter horizontal and vertical vibrations. These systems are vital for critical facilities such as nuclear plants, bridges, hospitals, important buildings, etc. where vertical vibrations can significantly affect the building's non-structural components and its overall stability. Although seismic isolation systems effectively reduce seismic risks, there is a continuing need for more research to develop more efficient and applicable systems in various geological and constructional conditions. The future requires a deeper understanding and development of advanced materials, adaptive control systems, and comprehensive 3D isolation solutions. [ABSTRACT FROM AUTHOR]

Modular polymer stormwater structures are a relatively new class of buried structure with two horizontal platens supported by vertical columns. While structural demand at design truck loads has been quantified, the ultimate limit state to design truck loading is unknown. Full-scale physical experiments were conducted to quantify the applied load and identify the mode(s) of failure at the ultimate limit state of three types of modular structures when buried (with 0.6 m soil cover) and subject to static design truck loading. All three module types tested reached an ultimate limit state at applied loads around three times the nominal design load but had different modes of failure. The ultimate resistance for the module with columns having the lowest moment of inertia relative to length squared was caused by column buckling and top platen rupture, while the two modules with nearly twice the moment of inertia relative to length squared failed by top platen rupture and their column forces at most were 70%–75% of their short-term single column buckling resistance. The results provide new data to allow independent load rating of the buried structure, support continued assessment of column buckling, and identify the need to limit platen bending deflections. [ABSTRACT FROM AUTHOR]

Based on the domain reduction method, this study employs an SEM-FEM hybrid workflow which integrates the advantages of the spectral element method (SEM) for flexible and highly efficient simulation of seismic wave propagation in a three-dimensional (3D) regional-scale geophysics model and the finite element method (FEM) for fine simulation of structural response including soil-structure interaction, and performs a physics-based simulation from initial fault rupture on an ancient wood structure. After verification of the hybrid workflow, a large-scale model of an ancient wood structure in the Beijing area, The Tower of Buddhist Incense, is established and its responses under the 1665 Tongxian earthquake and the 1730 Yiheyuan earthquake are simulated. The results from the simulated ground motion and seismic response of the wood structure under the two earthquakes demonstrate that this hybrid workflow can be employed to efficiently provide insight into the relationships between geophysical parameters and the structural response, and is of great significance toward accurate input for seismic simulation of structures under specific site and fault conditions. [ABSTRACT FROM AUTHOR]

A dynamic analysis of both twisting and regular towers is carried out to determine the results of considering soil-structure interaction (SSI) on high-rise buildings. In addition, the difference between the seismic performance of using twisting towers over regular ones is investigated. The twisting tower is a simulation of the Evolution Tower (Moscow). The towers' skeletons consist of RC elements and rest on a reinforced concrete piled-raft foundation. The soil model is considered as multi-layered with the same soil properties as the zone chosen for the analysis (New Mansoura City, Egypt). The only difference between both towers is their shape in elevation. The whole system is modelled and analyzed in a single step as one full 3D model, which is known as the direct approach in SSI. All analyses are carried out using finite-element software (Midas GTS NX). Dynamic output responses due to three records of seismic loads are proposed and presented in some graphs. Based on the results, it is concluded that SSI has a considerable effect on the dynamic response of tall buildings mainly because of the foundation flexibility, as it leads to lengthening the vibration period, increasing the story drift and the base shear for both cases. [ABSTRACT FROM AUTHOR]

In this work, a numerical study of the effects of soil-structure interaction (SSI) and granular material-structure interaction (GSI) on the nonlinear response and seismic capacity of flat-bottomed storage silos is conducted. A series of incremental dynamic analyses (IDA) are performed on a case of large reinforced concrete silo using 10 seismic recordings. The IDA results are given by two average IDA capacity curves, which are represented, as well as the seismic capacity of the studied structure, with and without a consideration of the SSI while accounting for the effect of GSI. These curves are used to quantify and evaluate the damage of the studied silo by utilizing two damage indices, one based on dissipated energy and the other on displacement and dissipated energy. The cumulative energy dissipation curves obtained by the average IDA capacity curves with and without SSI are presented as a function of the base shear, and these curves allow one to obtain the two critical points and the different limit states of the structure. It is observed that the SSI and GSI significantly influence the seismic response and capacity of the studied structure, particularly at higher levels of PGA. Moreover, the effect of the SSI reduces the damage index of the studied structure by 4%. [ABSTRACT FROM AUTHOR]

This article examines the effects of slope topography, soil non-linearity and soil-structure interaction (SSI) in hilly areas, where severe damage to hill buildings during past earthquakes were observed. Two-dimensional finite element analysis is carried out to simulate seismic response of hill buildings situated on the center of the slopes for three earthquake time histories. The influence of topographic amplification and SSI as a function of frequency of ground motion and site condition are examined. The present study shows significant ground motion amplification near the crest. It was found that the Seismic-Slope Topographic Amplification Factor (S-STAF) indicating the effect of slope on the seismic response, increases with the increase of slope angle and peak ground acceleration. However, S-STAF was increased by a margin as much as 30% when the non-linearity of the soil is considered. The effects of structural irregularity are also investigated by considering two types of buildings, (i) stepback and (ii) stepback and setback. Relative displacement of each story normalized with its height is reported as a drift ratio for two different slopes. The inter-story drift ratio of stepback building is slightly smaller than that of stepback and setback building. The seismic displacement of the slope increases significantly due to the presence of the building. The significant effect of SSI is observed with the increase of slope angle and this effect is much dependent on the earthquake characteristics. Further, period lengthening characteristics, seismic displacement, rocking and stress distribution of the footings of a stepback building on slopes are also investigated. [ABSTRACT FROM AUTHOR]

This research adopts emerging machine learning techniques to tackle the soil–structure interaction analysis problems of laterally loaded piles through physics-informed neural networks (PINNs), which employs prior physical information in the form of partial differential equations during the model training, eliminating the tremendous data requirement in the traditional data-driven machine learning methods. The formulations to describe the problem are discussed, and the corresponding governing equations are derived. A PINN framework, including neural networks architecture and loss functions, is developed for the machine learning-based solution and elaborated with details. The corresponding model training process is presented, based on which the surrogate model construction and back analysis implementation are introduced to demonstrate the effectiveness and flexibility of the proposed method. This method has been demonstrated for its accuracy via several examples with benchmark solutions from the existing well-developed methods. Finally, a case study of the uncertainty evaluation of a laterally loaded pile is conducted to illustrate its high computational efficiency and advantages in potential engineering applications. [ABSTRACT FROM AUTHOR]

The structure's ability to release energy through inelastic behaviour is reflected in the response reduction factor (R). It results from a combination of redundancy, ductility, and over strength. Thus, determining R with accurate values plays a critical function in the process of seismic design. This study aims to determine the response factor of structures of reinforced concrete (RC). With different structural irregularities, additionally, determine the impact of the interaction between soil and structure (SSI) using non-linear static pushover analysis was adopted in numerical simulation by using SAP2000. The selected irregularities included elevational and in-plan changes It was determined that, in comparison to regular buildings, buildings with irregular vertical geometries had poorer inelastic seismic capacities. Therefore, R is less than that which is stated in the ECP 2020, so it ought to be reduced by 15-40% before the design stage. The outcomes demonstrated that It isn't concluded that irregularity has a considerable effect on weak soil (C). The reduction in R, considering (SSI), reached 20.3% and 13.1% for fixed and isolated supports, respectively, in case of loose soil. Moreover, it became obvious that for the same structure the stiffer the base soil the greater the R's value. [ABSTRACT FROM AUTHOR]

The Hardening Soil-Brick model for soils is designed to carry out complex numerical analyses of soil-structure interaction problems taking into account strong stiffness variation in the range of small strains. However, to calibrate its parameters advanced triaxial and oedometric tests are required. In case of uncemented sands laboratory testing is usually difficult. Therefore, to facilitate calibration procedures, a CPTU based method, enhanced by an experimental evidence derived from advanced triaxial drained and oedometric tests, has been proposed and verified. It is shown in the paper that using exclusively the CPTU test results one can calibrate most important model parameters for sands with accuracy that is sufficient for solving real life problems. The major goal of this paper is to identify correlations between all reference stiffness moduli, then verify them, and finally link with the CPTU based identification procedures. It is shown in the paper that such correlations exist and they exhibit very high coefficients of determination. Moreover, as the seismic version of the CPTU test is not often available in the practice, an enhanced procedure for identification of very small strain shear stiffness modulus has been proposed and then verified, using set of the SCPTU tests conducted in Gdańsk sands (Poland). [ABSTRACT FROM AUTHOR]

This study proposes a constitutive model to simulate the clayey soil response to the external loads during soil-structure interaction, specifically in the context of pile installation and subsequent set-up. The model considers the alteration of soil structure during prolonged penetration and the gradual regaining of its thixotropic strength. The model is based on the disturbed state concept and critical state theory, with the Modified Cam-Clay model used to define the intact state response. The proposed model, referred to as the Critical State and Disturbed State Concept model, captures the elastoplastic behavior of both normally consolidated and over-consolidated soils. It was validated using triaxial test results and implemented in Abaqus software to simulate pile driving and the set-up phenomenon occurs after the end of pile driving. The model accurately predicts pile capacity and disturbance behavior in the soil, as demonstrated by field compression load tests. [ABSTRACT FROM AUTHOR]

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The grid-based multi-velocity field technique has become increasingly popular for simulating the Material Point Method (MPM) in contact problems. However, this traditional technique has some shortcomings, such as (1) early contact and contact penetration can occur when the contact conditions are unsuitable, and (2) the method is not available for contact problems involving rigid-nonrigid materials, which can cause numerical instability. This study presents a new hybrid contact approach for the MPM to address these limitations to simulate the soil and structure interactions. The approach combines the advantages of point-point and point-segment contacts to implement contact detection, satisfying the impenetrability condition and smoothing the corner contact problem. The proposed approach is first validated through a disk test on an inclined slope. Then, several typical cases, such as granular collapse, bearing capacity, and deformation of a flexible retaining wall, are simulated to demonstrate the robustness of the proposed approach compared with FEM or analytical solutions. Finally, the proposed method is used to simulate the impact of sand flow on a deformable structure. The results show that the proposed contact approach can well describe the phenomenon of soil-structure interaction problems.

Based on the ANSYS finite element software, the NREL 5 MW monopile offshore wind turbine tower system was modeled in 3D. The influence of different wind speeds on the dynamic characteristics of the tower structure was simulated and analyzed under the full consideration of the soil structure coupling effect and the impeller rotation. The six average wind speeds and the corresponding impeller speeds in the interval between the cut-in wind speed of 3 m/s and the cut-out wind speed of 25 m/s were selected as simulation conditions. The analysis results show that, with the increase of wind speed and impeller speed, the modal frequency of the tower structure gradually increases, and the first two modal frequencies change most obviously. Moreover, the peak value of the tower displacement increases as the wind speed and impeller speed increases, but the amplitude decreases. The displacement shows a non-linear growth trend. The equivalent stress value of the tower increases as the wind speed and impeller speed increases, but the change trend is different from the displacement, which is roughly linear. The fatigue life of the tower decreases sharply, but they are far more than the actual working hours, the fatigue damage and safety factor hazard values are mainly distributed at the bottom of the tower and at the single pile, consistent with the maximum equivalent stress distribution position.

The purpose of this study is mainly to investigate, through fragility curves, the effect of soil–structure interaction (when it is neglected during design) on damage probability. It also examines how realistic it is to conduct a performance estimation with rapid assessment methods without considering soil–structure interaction. Three RC frame buildings, with varying numbers of stories, were designed according to the Turkish Seismic Design Code, 2007. Incremental dynamic analyses of the considered structures, both with and without soil–structure interaction (SSI), were performed using 21 ground motion records to determine the damage limits. The cone model with springs was used to take soil–structure interaction into account. The discrete damage probabilities of each considered performance level were calculated, using statistical methods, in terms of elastic spectral acceleration, and continuous fragility curves were obtained. The results show that the effect of SSI on fragility was remarkable and that damage probability generally increases when soil–structure interaction is taken into consideration. The effect of site class becomes significant for life safety and collapse prevention performance levels. The increase in the probability of exceeding the collapse prevention performance level can reach up to 72% due to the existence of SSI. Thus, the results of damage estimation made without considering SSI can sometimes be significantly misleading.

This paper tests the capability of a simplified model to predict major trends in the dynamic structural response of monopile offshore wind turbines. For this purpose, the results of two numerical models of different levels of complexity are compared: the advanced time-domain multi-physics tool OpenFAST and a simplified static-equivalent model based on beam elements and concentrated masses. The IEA-15-240-RWT reference wind turbine is considered as a benchmarking problem. The comparison between the two structural models is presented in terms of their fundamental frequencies and through the analysis of shear forces and bending moments under wind-only and combined wave and wind load scenarios. The results show that the simplified model can adequately represent the system’s mass and stiffness characteristics, as well as the impact of soil–structure interaction effects on its fundamental frequency. Turbulence and wind velocity have a significant impact on internal forces and on the ability of the simplified model to reproduce their values. Despite the large differences obtained for highly turbulent scenarios, the acceptable accuracy obtained for relevant load scenarios and the conservative nature of the simplified model make it a viable option for preliminary large-scale studies that prioritize efficiency and efficacy over high-precision.

The foundation pit area of Kunming International Comprehensive Transportation Hub is 56,800 m2, and the excavation depth ranges from 18 m to 25 m. Because the surrounding environment is very complex, the foundation pit is supported by an underground continuous wall and three layers of internal support system with seven rings. The force of this internal support system is coupled integrally, and the number of rings is the highest in the world at present. In this work, a finite element model considering the interaction between soil and the retaining structure is established. The Hardening Soil model with small strain stiffness is used to simulate and analyze the whole excavation process of the foundation pit. Considering the ultra-large plane size of the foundation pit, we cannot ignore the temperature effect, so the deformation of the underground continuous wall and the force of the internal support system under seasonal temperature variation are investigated. By comparing numerical simulation results with field measurements, the deformation of the ultra-large seven-ring internal support system, the deformation of the surrounding soil, and the axial force of the supports are analyzed. The results show that the finite element simulation agrees well with the measured data. This work provides a reliable method for analyzing ultra-large deep foundation pits.

This study investigates the control of seismic and wind-induced responses in reinforced concrete chimneys, incorporating material nonlinearity and soil–structure interaction. Using the Force Analogy Method (FAM), an innovative approach for nonlinear dynamic analysis, the performance of tuned mass dampers (TMDs) is evaluated under diverse loading scenarios, including seismic sequences with mainshock–aftershock events and wind-induced loads, due to synoptic and hurricane winds, modeled as stochastic processes. The FAM approach enables computationally efficient analysis, effectively capturing the complex interactions between seismic and wind actions across varying soil foundation conditions. The results demonstrate the effectiveness of TMDs in reducing structural responses across various loading and foundation scenarios, emphasizing their efficiency in enhancing the safety and resilience of slender structures. This research provides valuable insights into the application of vibration control strategies for safeguarding critical infrastructure against extreme environmental loads.

In this study, the difference between the displacements of structures (relative displacement) is selected as the control parameter in pounding problems. During an earthquake, an increase in the amplitude of relative displacement between adjacent structures indicates a potential pounding condition. Within the scope of this study, the optimal distribution of linear viscous dampers between adjacent structures and the effect of soil on this distribution are investigated. The structure is intended to be modeled in two different ways through rigid and three sandy soil models (loose, medium-dense, and dense) at the foundation level. Different analyses are performed by changing the total damping coefficient considering the 1st and 2nd modes of the coupled models of adjacent structures. The study presents important findings on how to design dampers to prevent pounding problems in adjacent buildings, especially in seismically hazardous regions. Within this study, an adjacent building model 5-5 story is examined. The optimum damping coefficients are compared, and their effectiveness is demonstrated using the first periods of both adjacent building models. The proposed method in the study shows that it is possible to minimize the collisions of adjacent structures with the optimum placement of viscous dampers. The method shown is quite effective for the design of dampers that will be added to the structures later or at the initial stage.

The concept of rocking foundations has been successfully tested and promoted for building and bridge foundations. In this paper, the applicability of rocking foundations to wind turbines is investigated, specifically for wind turbines constructed on undrained clay. An efficient form of von Mises constitutive model with non-linear kinematic hardening is integrated with the ABAQUS finite element software by a computer code and validated against experimental data. A cohesive contact of foundation–soil with limited tension is applied to simulate suction stresses at the foundation bottom–soil interface, which better represented the rocking foundation behavior. The obtained finite element results demonstrate that by allowing minimal foundation uplift under operational loads, an existing foundation can be used to support loads from a larger wind turbine than it is designed for. Allowing such uplifts corresponds to a rocking foundation design that is demonstrated in this paper to be safe and functional for a wind turbine under both operational and extreme conditions.