Influence Of Soil-structure Interaction Research Articles

Influence of Soil Structure Interaction on Seismic Performance of Steel Structure Interaction with Different Types of Foundations and Soil

Influence of Soil Structure Interaction on Seismic Performance of Steel Structure Interaction with Different Types of Foundations and Soil

Influence of pulse-like motions and extreme environmental loads on the seismic foundation response of offshore wind turbines on layered liquefiable soils

Monopile foundations are known as the most common foundation solution for offshore wind turbines (OWTs). However, the state of practice for designing monopile foundations in high seismicity areas is still limited. In particular, the impact of soil liquefaction on the seismic soil-foundation-OWT interaction is not yet well understood. In this paper, three-dimensional (3D), fully-coupled, nonlinear finite-element analyses performed in the OpenSees numerical platform were used to evaluate the seismic performance of a series of hypothetical 5 MW OWTs on monopile foundations in layered, liquefiable sites. A suite of earthquake recordings with and without strong velocity pulses (i.e., near fault, pulse-like and ordinary motions, respectively) was used to investigate the impact of ground motion characteristics on the seismic response of the OWT system. Also, the influence of soil-structure interaction and earthquake shaking coupled with extreme environmental loading (i.e., wind and wave loads) on the seismic performance of soil-OWT systems was evaluated. The numerical results showed pile movements induced by extreme climate loading led to a bias in permanent settlement accumulation across the foundation area and accumulation of soil deformations in the proximity of the pile. Ground motion velocity pulses increased the cyclic stress demand in soil and, therefore, the potential for the occurrence of soil liquefaction. A subsequent, limited numerical sensitivity study showed that the foundation rotations of the OWT system were influenced by ground motion characteristics such as polarity and velocity pulses, and the presence of the wind and wave loads. The cumulative absolute velocity (CAV) was identified as the optimum ground motion intensity measure for permanent foundation settlement and tilt as well as for peak transient foundation tilt of the OWT system under extreme environmental loadings. The net outcome of these factors determined the magnitude and orientation of the foundation rotations at the end of shaking. This study highlights the importance of considering the effects of extreme loadings and pulse-like motions in the design and performance of OWT systems.

Failure mechanisms and seismic fragility analysis of overhead transmission lines incorporating pile-soil-structure interaction

Overhead transmission lines (OTLs) are responsible for long-distance electric power transmission from power plants to end-users, inevitably passing through seismically active regions. A thorough literature review regarding seismic design and assessment of various structures underscores the significance of incorporating soil-structure interaction (SSI) and depth-varying spatial effect (DVSE). However, previous studies typically assumed that OTLs are fixed directly to the ground, and depth-varying ground motions (DVGMs) are oversimplified as uniform excitations, which may yield questionable structural performance estimations. To address this concern, this paper focuses on investigating the SSI effect on the seismic response and failure mechanism of an OTL subjected to DVGMs. Prior to this investigation, two commonly used methods for modeling the SSI effect in software ABAQUS are compared, with a nonlinear spring-based modeling method deems comparable in accuracy yet superior in efficiency. Subsequently, a refined finite element model of an OTL-soil-pile system is developed utilizing this simplified modeling method, and a group of three-dimensional ground motions varying within layered soils is stochastically synthesized. The influences of SSI and DVSE are systematically explored in terms of the seismic responses, failure mechanisms, and fragility probabilities of the OTL. The results expose the potential of the SSI effect to weaken the seismic capacity of the OTL and increase the risk of failure, while disregarding the DVSE is likely to lead to overestimated outcomes. This research is expected to raise awareness of considering SSI and DVSE in the seismic design and analysis of OTLs.

Dynamic soil–structure interaction of a three-span railway bridge subject to high-speed train passage

In this study, the influence of Soil-Structure Interaction (SSI) on the dynamic behavior of a three-span concrete slab railway bridge with integrated retaining walls is investigated. The bridge is subjected to controlled excitations using a hydraulic actuator with different frequencies and load amplitudes. A 3D model of the railway bridge-soil system is implemented and calibrated using the experimental frequency response functions at each sensor location. A soil-free model is also created to compare with the calibrated model. It is observed that the dynamic behavior of the railway bridge is substantially altered by the presence of the surrounding soils, and neglecting SSI can lead to underestimation and inaccurate results. Additionally, the calibrated model is used for further train-passage analyses. For the studied bridge, neglecting SSI increases the maximum acceleration response of the bridge during high-speed train passages from 5.5 m/s2 up to 14.5 m/s2. It is also shown that the response of the bridge during train passage is predominantly influenced by its first bending mode, with higher modes inducing no discernible effect. Finally, parametric studies are performed in order to study the uncertainties related to the soil properties.

Seismic analysis of integral bridge considering the influence of soil structure interaction

AbstractIn Simply supported bridge, superstructure and substructure are separated by the expansion joint and bearing. In Integral bridge (IB), the bridge deck is casted monolithically with the abutment wall. Integral bridges have increased redundancy, which improves its seismic performance. Simply supported Bridge fails may fail due to the failure of bearing, non‐availability of seating width and failure of expansion joint which does not occur in the IB. The single pile analysis performed in Csi bridge and L pile software with same soil and pile parameter shows that the soil parameters from API guideline can be used in the FEM to represent the SPI. The FE modelling of a benchmark IB is modelled in Csi Bridge. Soil surrounding the pile is represented by the series of nonlinear spring p–y curve, t‐z curve and q‐z curve based on API. Seismic Capacity of benchmark IB is determined using nonlinear static analysis in which nonlinearity is assigned in soil and pile. The forces induced in piles are observed to be within the elastic capacity. Parametric study with variation of soil (loose sand, medium sand and stiff clay) by Nonlinear static analysis shows stiffness of soil has significant effect on seismic response.

Influence of soil-structure interaction on the dynamic characteristics of railroad frame bridges

Explicit dynamic calculations are required in various standards for bridges on high-speed lines to ensure normative limits. This dynamic analysis is based on the resonance phenomena between the train crossing and the frame's natural frequencies in bending. It is obvious that, especially here, an exact determination of the natural frequencies in the numerical models is important for determining the resonance speed, as there is no conservative consideration in dynamics. Furthermore, considering radiation damping based on soil-dynamic approaches can noticeably reduce the maximum amplitudes at the resonance point when simulating train crossings. However, due to the massive dimensions of structural members and a large number of constraints, the dynamic system of railroad frame bridges is usually not clearly to be identified. Hence, a prediction of natural frequency and radiation damping are currently large uncertainties for the design of frame bridges, making dynamically good-natured behaviour, characterised by large damping, particularly desirable.This paper examines the dynamic behaviour of embedded frame bridges, including the effect of soil-structure interaction, under 2D and 3D numerical approaches. Different modelling methods with respect to the unbounded domain and the satisfaction of the Sommerfeld's radiation condition are compared: (1) direct modelling using tuned damper elements, (2) coupled BEM-FEM, and (3) simplified substructure method. It is shown that the coupled FEM-BEM approach reproduces the relationships of three-dimensional dynamic soil-structure interaction (SSI) more accurately than a planar FEM approach since the SSI does not result independently of the chosen modelling method, which is reflected in divergent radiation damping. Furthermore, the governing rigid body modes can be identified using a simplified substructure method.The following parameters influencing the SSI are investigated and discussed in detail: (a) influence of the soil stiffness; mainly described by the ratio between the natural frequencies of the frame and the soil-abutment system, (b) layering of the underlying soil, (c) degree of superstructure clamping, and (d) material properties of the backfill. It is shown that the natural frequencies react robustly to the SSI and are thus mainly influenced by the structural stiffness of the frame. In contrast, radiation damping exhibits various dependencies. In particular, the superstructure slab's clamping ratio and the vertical rigid-body mode frequency (direct relation to soil stiffness) should be mentioned here, significantly influencing the vibrating system. Finally, based on these results, a recommendation for the dynamic design is given.

Urban scale risk assessment including SSI and site amplification

Large-scale risk analysis is typically performed considering existing fragility curves, calculated in most cases without adequately accounting for local site amplification (SAmp) and soil-structure interaction (SSI) effects. Nevertheless, foundation flexibility and local site effects may lead to a substantial difference in the fragility or loss estimates. Including these effects on the city-scale vulnerability analysis is challenging due to the complexity of defining the whole interacting urban system. We propose a novel framework for the fragility assessment of structures considering the influence of SSI and local site amplification effects, suitable for large-scale applications. The applicability of the proposed approach is based on globally available data regarding the soil, the foundation, and the building portfolio. Site amplification is considered directly in the resulting fragility curves using site response analyses. An improved taxonomy is adopted to make the approach implementable in the OpenQuake software, introducing VS,30 and H/B within the structural features as proxies for the site and SSI effects. Finally, following the performance-based earthquake engineering framework, the outcomes of the methodological framework are adopted to estimate the nominal probability of failure for selected building classes belonging to the majority of structural types of the city of Thessaloniki, Northern Greece. The main findings demonstrate that the conventional way of calculating fragility curves may lead to a different seismic risk evaluation, especially in soft soil formations.

Study Behaviour of PEB Structure with Isolated Foundation Considering Soil Structure Interaction

Abstract: In this study behaviour and concept of Pre- Engineered structure & SSI is included. Behavioural study of preengineered building is observed in this paper. Soil structure interaction (SSI) taken into consideration to study the interface between Soil and the structure rested on that soil. Many resources can be used to gather information on the present theories and practices, including IEEE explorer, technical papers, journal, conferences, patent information research thesis, international and national workshop proceedings. The following case studies the influence of soil structure interaction on pre-engineered building (PEB). By considering the fixed support conditions at the base of structure, the structural behaviour is analysed. The structural response of building seems to be affected because in conventional method the foundation flexibility of soil mass has been ignored. Winkler’s spring model approach is used for the analysis of soil flexibility by integrating. The effect of SSI on various parameters like base shear, lateral displacement, etc. are studied and discussed. The subgrade must be modelled adequately well to get real behaviour of superstructure. The analysis is administered in STAAD Pro. connect edition software using response spectra of IS 1893-2016

A comparative study to determine seismic response of the box culvert wing wall under influence of soil-structure interaction considering different ground motions

The present study deals with evaluation of the effects of different ground motions, backfill-structure interaction (BSI) and soil-structure interaction (SSI) on dynamic response of a box culvert wing wall. In obtaining numerical results, five different earthquake records with different frequency contents, five different backfill types and four different subsoil types are taken into account. Firstly, a finite element model (FEM) and three analytical models are proposed for analysis of the wing wall-backfill system under fixed-base case, and these fixed-base models are compared with each other through both modal analysis and displacement time-history analysis under the assumption of linear-elasticity. After validating the ability of the FEM approach, by extending the fixed-base FEM to take account of elastoplastic behavior of soil and SSI, a three dimensional (3-D) model has been described, and 3-D nonlinear analyses have been carried out in time domain. The numerical results show that the seismic response of the wing walls are affected remarkably by the SSI, BSI and frequency content of the earthquake.

Seismic Analysis of Irregular Reinforced Concrete Building Considering Soil Structure Interaction

Abstract: According to several studies on past earthquakes, Dynamic loading influences the seismic reaction of buildings. Sudden distress and failures in structures have been seen as a result of soil-structure interaction. Soil-structure interaction increases shear stresses in the structure's bottom storeys, making it less rigid and increasing lateral displacements such as storey drift, inter-storey drift, and roof displacements. Increased lateral displacements in high-rise buildings cause occupant discomfort. The interaction between soil and structure lengthens the building's natural time period. Three modelling approaches, fix foundation building, medium stiff base building, and low stiff base building, have been investigated and analysed using SAP2000 V14, taking into account soil-structure interaction (SSI). The results can be used to build a detailed performance-based seismic design approach that considers the influence of soil structure interaction. Keywords: Seismic Analysis, Soil Structure Interaction, Seismic Response, SAP2000

Influence of Soil-Structure Interaction on the Seismic Response of a Continuous Bridge with Friction Pendulum System

A three-dimensional finite element analysis was carried out for the influence of soil-structure interaction (SSI) on the seismic response of an isolated continuous bridge with a friction pendulum system (FPS). SSI was modelled using the soil resistance vs deflection nonlinear springs (following p-y curves). The influence of SSI on the dynamic behaviour and the seismic response of isolated bridges with different friction coefficients of FPS were investigated using six measured ground motions. Results show that the effect of SSI is limited on the isolation period of the bridge, but significant on the response amplitude of the bridge structures, and particularly on the response amplitude at the pier top and bottom. The displacement and acceleration at the pier top are underestimated, while the shear force and bending moment at the pier bottom are overestimated if the SSI effects are ignored, which suggests that SSI should be considered in the seismic analyses of continuous bridges.

Seismic soil structure interaction of reinforced concrete frame building supported on foundations

Soil Structure Interaction (SSI) determines the response of structures during seismic activity. An engineering review committee deals only with the study of soil structure interaction as compared to free motion, gives an appreciable impact on the basement motion. This article investigates the influence of soil structure interaction on RC frame building with seismic excitations. By taking different cases like 5, 10, 15, 20 storey of varying soil types are type I, type II and type III, different foundation types are isolated, combined, mat, pile. The entire foundation-soil-structure system is modelled and analyzed in a finite element based SAP2000 Software, to study the stress on soil and framed structure in the presence of SSI. Finally, a comparative study between with and without SSI to reinforced concrete framed structure is done. The study shows that SSI effects are higher than regular approach if we include the SSI effects in our analysis and design of structure to get a safety design.

Effects of Soil-Structure Interaction on Torsionally Coupled Base Isolated Machine Foundation under Earthquake Load

In this paper, the influence of soil-structure interaction (SSI) on a torsionally coupled turbo-generator (TG) machine foundation is studied under earthquake ground motions. The beneficial effects of base isolators in the TG foundation under earthquake ground motions are also studied duly, considering the effects of SSI. A typical TG foundation is analyzed using a three-dimensional finite element (FE) model. Two superstructure eccentricity ratios are considered to represent the torsional coupling. Soft soil properties are considered to study the effects of SSI. This research concludes that the effects of torsional coupling alter the natural frequencies, if ignored, could lead to unsafe design. The deck accelerations and displacements are increased with an increase in superstructure eccentricity. On the other hand, the deck accelerations and displacements are greatly reduced with the help of base isolators, thus confirming the beneficial use of base isolators in machine foundations to protect the sensitive equipment from the strong earthquake ground motions. However, the effects of SSI reduce the natural frequencies of the TG foundation resting on soft soil conditions and activate the higher mode participation, resulting in amplifying the response.

EVALUATION OF STRESS OF BOX CULVERT FOR AGRICULTURAL DAM

The current design for culverts is based on a two-dimensional analysis and only addresses the internal forces of the culvert members in the cross-section. The stress of a culvert in the direction of the culvert axis has not been given much attention; thus, there are no specific guidelines or provisions for it in the current standards. In the case of a culvert under a fill-dam placed on a soft foundation, the differences in settlement along the culvert axis may cause bending stress or tensile stress at the bottom of the culvert in the culvert axis direction. When this stress is beyond the capacity of the culvert material, excessive deformation and cracks in the culvert can occur. In the present study, this issue was explored through both two-dimensional (2D) and three-dimensional (3D) finite element methods (FEMs). This study reveals that the 2D plane strain FEM, although it can model with soil-structure interaction, it is incapable of recognizing stress along the culvert axis. In contrast, the 2D plane strain FEM can determine that stress but can not consider the influence of soilstructure interaction. Meanwhile, the 3D FEM provides excellent soil-structure interaction and considers the actual shape of the structures. Based on the results, it was shown that the 2D FEM is unreliable in its assessment of the tensile stress along the culvert axis compared to the 3D FEM when the box culvert was placed on a soft, deep foundation. The findings also revealed that when the foundation was soft (the stiffness of the foundation was low), other parameters such as the height of the dam and the depth of the foundation had a significant effect on the tensile stress at the bottom of the box culvert in the direction of the culvert axis.

Influence of Soil-Structure Interaction on Seismic Response of Multi-Storey Buildings

In the seismic analysis of a structure resting on the ground, the response of the sub-soil affects the response of the structure and vice versa. Also, the structure displacements and the ground displacements are not independent of each other. This phenomenon is called soil structure interaction (SSI). In this study, to evaluate the effects of SSI on seismic response of multi-storey buildings, three dimensional analyses were performed on moment-resisting frames resting on different soil types with different shear wave velocities and shear moduli, representing soil classes: B, C, and D according to ECP (201, 2011). Three structural models, consisting of five, eight, and ten storey models, have been analyzed using ABAQUS software under two base conditions: fixed base condition, and flexible base condition “considering SSI effects”. Two ground motions (El Centro 1940, and Kobe 1995) have been chosen for the required analysis. The results of the selected cases indicate that base shear forces generally decrease by decreasing the shear wave velocity and shear modulus of the subsoil. Thus, considering SSI effects in the seismic analysis of moment-resisting frames is essential to guarantee both economical and safe design of multi-storey buildings.

Influence of soil-structure interaction (SSI) on optimal design of passive damping devices

Recently, the interest in research for optimization of viscous dampers in design of buildings has been increasing. In this study, the effect of soil-structure interaction has been taken into account for the purpose of optimal design of viscous dampers. A damper optimization method based on a target damping ratio and interstorey drift ratio found in literature has been adapted for a building structure model considering different types of sandy soils. While passive constraints have been taken as upper and lower limits of each damper, active constraints have been considered as a target damping ratio in terms of damping coefficients. The proposed algorithm includes time history analyses that test the designer’s optimal design. Interstorey drift ratios under design earthquakes have been checked at each design step. The first and second mode responses have been considered separately. According to the results obtained from this study, the negative impact of sandy soils on the dynamic behavior of superstructures can be overcome by optimal placement of dampers in buildings. The results of the analyses have shown that soil effects should be taken into account in solving damper optimization problems.

Influencia de la interacción suelo-estructura en el comportamiento de las viviendas aporticadas con zapatas aisladas en la ciudad de Juliaca

La respuesta estructural ante un sismo de un edificio de concreto armado se ve afectado por la interacción de tres componentes: el suelo, la cimentación y la estructura. El propósito del presente es determinar la influencia de la interacción suelo-estructura en el comportamiento de las viviendas a porticadas en la ciudad de Juliaca, Perú. El método incorporo la flexibilidad del suelo según las recomendaciones de la FEMA 356/440 además de verificar el desempeño y las respuestas sísmicas entre los modelos con base empotrada y base flexible en los diferentes puntos de estudio, para los edificios con planta cuadrada de 2 y 3 pisos. Los principales resultados muestran que la influencia de la interacción suelo-estructura no es significativa, sin embargo, en los edificios de 4 y 5 pisos el efecto es muy significativo. Los edificios con planta rectangular de 2 pisos al asignar la flexibilidad en la base de fundación no son significativos, en cambio en los edificios de 3, 4 y 5 pisos presentan mayor efecto de la interacción suelo-estructura. En términos de fuerzas cortantes y los momentos de volteo el incremento de la interacción suelo-estructura no supera el 1%, por lo tanto, no modifica la resistencia del edifico.

Natural period of reinforced concrete building frames on pile foundation considering seismic soil-structure interaction effects

The magnitude of seismic forces induced within a building, during an earthquake, depends on its natural period of vibration. The traditional approach is to assume the base of the building to be fixed for the estimation of the natural period and ignore the influence of soil-structure interaction (SSI) citing it to be beneficial. However, for buildings resting on soft soils, the soil-foundation system imparts flexibility at the base of the building and it is imperative for SSI effects to exist that may prove to be detrimental. Presence of SSI effects modifies the seismic forces induced within the building, which is dependent on the change in its fixed base natural period. Expressions for determination of the natural period of a structural system under the influence of SSI (effective natural period) are available in the literature. Although useful and made applicable to all types of foundation systems, these expressions are developed either using simplified models or are applicable to shallow foundations and may not be suitable to all types of structural-foundation systems in general. This article investigates the influence of seismic soil-structure interaction on the natural period of RC building frame supported on pile foundations. Detailed finite element modelling of an exhaustive number of models, encompassing various parameters of the structure, soil, and the pile foundation has been carried out in OpenSEES to study the effect of SSI on the natural period of the RC building frame. The effect of various parameters on the natural period of the building frame under SSI is investigated and the results have been used to develop an ANN architecture model for the estimation of the effective natural period of RC building frame supported by pile foundation. Garson’s algorithm is used to conduct sensitivity analysis for examining the importance of various parameters that govern the determination of effective natural period. A predictive relationship for obtaining the effective natural period has been proposed using ANN architecture in the form of a modification factor that is to be applied on the fixed base natural period, and which depends on various input parameters of the building frame-pile-soil system. A comparison of the proposed relationship with those available in literature demonstrates its usefulness and applicability to RC building frames on pile foundations.

Fragility curve modifiers for reinforced concrete dual buildings, including nonlinear site effects and soil–structure interaction

We investigate the influence of soil–structure interaction (SSI) and nonlinear soil behavior on the seismic fragility of reinforced concrete (RC) dual (frame + shear wall) buildings resting on shallow foundations. This article includes a holistic methodology to account for nonlinear soil behavior and soil–foundation–structure interaction in a modular way. Using nonlinear dynamic analyses, we derive fragility curves for a wide set of building typologies and soil profiles, showing that soil behavior during strong shaking significantly affects the vulnerability of the soil–foundation–structure system. The influence of SSI is pronounced mostly for soft soil profiles, varying in a building-specific way. Post-processing of our results evolves into a set of fragility modifiers that enable risk analysts to massively account for soil-related and/or SSI effects in large-scale risk assessments.

Analyzing the Effects of Soil-Structure Interactions on the Static Response of Onshore Wind Turbine Foundations Using Finite Element Method

The use of wind turbines to generate electricity has increased in recent years. One of the most important parts of a wind turbine is the foundation, which should be designed accurately because it is influenced by difference forces. Soil cannot carry tension stress; thus, when a wind turbine foundation is applied eccentricity forces, a gap appears between the soil and foundation. The gap will have no positive effect on the ultimate bearing capacity of the foundation. This must be considered when designing the dimensions of an onshore wind turbine on a spread foundation using finite element software in order to avoid error during analysis. In the current study, a spread foundation of an onshore wind turbine was simulated using ABAQUS and PLAXIS-3D software. Based on the results, the effects of Soil-Structure Interaction (SSI), eccentricity of forces, soil strength parameters and the foundation buried depth on static response of the foundation are discussed. The results indicate that the influence of soil-structure interaction is depend on magnitude of eccentricity of forces and depth of foundation, so that soil-structure interaction has little impact on settlement of foundation when eccentricity of forces is less than 1/6 of the diameter of the foundation and this has important effect when the eccentricity forces at an amount exceeding 1/6 of the diameter of the foundation. In addition, this effect decreases with increasing the foundation buried depth and independent of the soil strength parameters (φ´ and C).