Role Of Soil-structure Interaction Research Articles

Suitable intensity measures for 3D steel structures

Intensity Measures (IMs) play a crucial role in assessing the performance of structures. The central question is how to find an IM that represents the destructive power of an earthquake. The problem becomes more complex considering the Soil-Structure Interaction (SSI) and the 3D state. This study tries to find the best IM for 3D steel structures by analyzing two eight-story buildings with different structural systems under eighty-one seismic records. Twenty-two IMs, five engineering demand parameters, and four combination methods are used. One of the structures is reanalyzed after removing the SSI to understand the difference. The five IM assessment criteria used in the research are efficiency, sufficiency, practicality, proficiency, and hazard computability. Updated frameworks are used for the assessment criteria to make the results comparable. The results shed light on the suitable IM, the best combination method, the effect of the structural system, and the role of SSI.

The role of Soil Structure Interaction (SSI) on the risk of pounding between low-rise buildings

The risk of pounding between adjacent structures during earthquakes may considerably depend on the effects of Soil Structure Interaction (SSI) between the soil, the foundation and the structures. The paper considers two adjacent low-rise buildings with different lateral stiffness and founded on shallow foundations. Overcoming most of the existing literature, this paper proposes advanced numerical 3D models (soil + foundation + buildings) by performing OpenSees that models the non-linear mechanisms of the soil and may realistically represent the mutual role of soil deformability and structural flexibility. A parametric study is performed on several soil layers with the aim to represent code-defined soil typologies.

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.

The role of soil structure interaction (SSI) on seismic response of tall buildings with variable embedded depths by experimental and numerical approaches

The soil-structure interaction is an integral part of the seismic evaluation, especially for structures with variable embedment depths. The purpose of this work is to ensure the adequacy of the small scaling factor in the dynamic analysis and study the seismic behavior of tall building with considering variable embedment depths and soil structure interaction effects. Therefore, scaled model tests of a 15-story steel structure were performed using shaking table tests and numerical simulations. Three scaled earthquake records, namely: Chi-Chi (1999), Northridge (1994), and Kobe (1995), were selected. The numerical scaled coupled models were implemented with Plaxis 3D software and validated with the experimental observations. Afterward, the experimental and numerical results of scaled models were verified with prototype models to ensure the adequacy of the small scaling coefficient. The results generated from small-scale models derived from experimental and numerical simulations were in good agreement. In addition, these results achieved good accuracy with full-scale field conditions in the seismic analysis. Therefore, a small geometric scaling coefficient of 1:50 achieved good accuracy for buildings with embedded parts to represent the dynamic behavior of structures. Within the frame results, it is noted that the SSI has an essential role in amplifying the lateral deflection of structures compared with a fixed base and thus the embedded depths significantly affect the lateral seismic response of the considered structures.

The Role of Soil Structure Interaction on the Seismic Resilience of Isolated Structures

Resilience has become an interesting parameter to assess the seismic risk connected with functionality of structures. In this regard, losses due to earthquakes may be significantly reduced by applying isolation at the base of the structures. However, design of isolation needs to consider the effects of soil deformability and all the connected effects of Soil Structure Interaction (SSI). In particular, soil deformability may reduce significantly the benefit of base isolation and thus the computation of resilience needs to consider such conditions. This paper aims to consider the issue by considering several isolated configurations on different soil conditions and for each of them, the seismic resilience has been computed. Numerical simulations have been performed in order to calculate the resilience of the various configurations and then this parameter was chosen a reference for comparing the isolation models on different soil conditions.

Model updating of a masonry tower based on operational modal analysis: The role of soil-structure interaction

Vibration-based finite element model (FEM) updating of cultural heritage assets is gaining so much attraction these days since destructive tests are usually not allowed to be performed. In this study, a framework for developing three-dimensional (3D) FEMs is proposed using 3D laser scanners and applied on Slottsfjell tower, a stone masonry tower in Tønsberg, Norway. Operational modal analysis (OMA) was done based on the ambient vibration testing (AVT) data to define the frequency values and corresponding mode shapes of the tower. Mechanical properties of the tønsbergite stone were utilized to derive the base values of the material properties of the homogenized masonry for performing sensitivity analysis and FEM updating. To investigate the effect of the soil-structure interaction (SSI) on the FEM updating results, three FEMs are developed. The fixed-base model is the FEM without considering the SSI effects, and two other FEMs are developed using the substructure and direct methods for simulating the SSI effects. Sensitivity analysis was performed to investigate the effective parameters on the dynamic characteristics of the models. FEM updating was conducted on the three FEMs, and results are compared to each other to show the role of the SSI on the FEM updating results. The resonance effect can cause damages to buildings located even in low seismicity zones. For this aim, the risk of resonance effect has been evaluated for the tower. Finally, linear dynamic analysis was performed on the three calibrated models, and the results were compared to each other.

Probabilistic Structural System Response to Differential Settlement Resulting from Spatially Variable Soil

The role of spatially variable soil stiffness and strength on structural performance has been increasingly recognized with the rapid development of geotechnical reliability-based design tools. Performance criteria linked to the angular distortion between foundations and the probability of exceeding certain limit states as a function of linear-elastic soil property autocorrelation have shed light on the link between foundation soils and potential structural damage. However, the role of soil-structure interaction (SSI), especially considering nonlinearity in soil and structural elements, to redistribute shear and flexure within structures that result from differential foundation movements, has been largely neglected. This study presents a critical examination of the effect of nonlinear SSI to redistribute flexural demands within a steel structure founded in soils exhibiting spatial variability and the corresponding differential settlements through a comparison of uncoupled and coupled Monte Carlo simulations (MCS). This study shows that the differential settlement, Δs, computed using coupled (i.e., SSI) analyses are significantly smaller than those derived from the uncoupled analyses for the random field models (RFMs) used to simulate soil spatial variability. The effect of SSI is to substantially reduce the probability of exceeding selected limit state criteria due to differential movements that vary in magnitude with the level of stringency of the limit state criteria; the most significant reduction corresponds to the structural ultimate limit state (ULS). Furthermore, the effect of SSI on structural performance and the critical scale of fluctuation, δcrit, becomes more apparent and beneficial as the severity of differential movement increases. Smaller and/or “allowable” angular distortions are governed by the local footing-to-footing distance, whereas the probability of exceeding the ULS (i.e., yielding of beams) is controlled by the entire structure working to redistribute the flexural demands. Limit state severity appears to control the critical soil autocorrelation length for angular distortion, indicating that the role of SSI in the performance of structures in spatially varying soils cannot be ignored.

The Role of Soil Structure Interaction in the Fragility Assessment of HP/HT Unburied Subsea Pipelines

Subsea high pressure/high temperature (HP/HT) pipelines may be significantly affected by the effects of soil structure interaction (SSI) when subjected to earthquakes. Numerical simulations are herein applied to assess the role of soil deformability on the seismic vulnerability of an unburied pipeline. Overcoming most of the contributions existing in the literature, this paper proposes a comprehensive 3D model of the system (soil + pipeline) by performing OpenSees that allows the representation of non-linear mechanisms of the soil and may realistically assess the induced damage caused by the mutual interaction of buckling and seismic loads. Analytical fragility curves are herein derived to evaluate the role of soil structure interaction in the assessment of the vulnerability of a benchmark HP/HT unburied subsea pipeline. The probability of exceeding selected limit states was based on the definition of credited failure criteria.

The probabilistic seismic assessment of aged concrete arch bridges: The role of soil-structure interaction

This study aims to investigate the effect of soil-structure interaction (SSI) on the seismic response of a medium-span old concrete arch bridge in Iran's railway network, through incremental dynamic analysis (IDA). To this end, the finite element model of the bridge was developed and its dynamic properties were calibrated based on experimental results. The effect of soil-foundation flexibility was taken into consideration in the computational model. Results from analyses were summarized in IDA curves and the effect of SSI was assessed through the probabilistic framework. To this end, the failure state of bridges was evaluated and a comparison was made between the rigid and flexible base models. The mean annual frequency of exceeding the failure state of the rigid-base bridge was also compared with flexible-base models to investigate the effect of SSI on the return period of failure state of the bridge. Furthermore, the SSI effects were assessed on the confidence level of bridge safety. Results show that ignoring the SSI effect leads to an overestimation of bridge capacity as well as the confidence level of satisfying the safety state. Similarly, the return period of bridge failure increases when a rigid-base model is employed.

Role of SSI on seismic performance of nuclear reactors: A case study for a UK nuclear site

The role of soil-structure interaction (SSI) on the risk of unacceptable performance of five non-structural components of a nuclear reactor is investigated through a representative case study consisting of a pressurized-water reactor sited at Holyhead, United Kingdom. The seismic hazard at the site is defined by a 10,000 years uniform hazard spectrum, and its corresponding design response spectrum computed for a target structural performance goal of 1 × 10−5. Nine hypothetical soil profiles, with shear wave velocities ranging from 300 m/s to 1,200 m/s, are considered. Non-linear site response analyses are performed to determine the input motion at the foundation level; seismic capacity and demand of the components are computed using response-history analyses. To obtain high-confidence performance estimates from a limited number of results, Monte-Carlo simulation is used to expand the seismic demand matrix. It is shown that the probability of unacceptable performance of the reactor is highly sensitive to SSI effects. Specifically, the beneficial effects induced by SSI on the seismic performance of the reactor are limited to models sited on stiffer soil deposits (ie, Vs ≥ 900 m/s), whereas, the median probability of unacceptable performance increases for medium-to-soft deposits.

Evidence of coupled soil-structure interaction and site response in continuous viaducts from ambient vibration tests

The scope of this research was to identify the significance of soil-structure interaction and site response on the dynamic behaviour of continuous multispan reinforced concrete viaducts, based on ambient vibration measurements and numerical simulations, using finite element models. For this purpose, an 875 m long bridge, located in Central Italy, founded on piles in eluvial-colluvial soil deposit was instrumented and ambient vibration tests together with geophysical investigations were performed. Experimental modal properties were evaluated by means of the operational modal analysis on accelerometric data and the role of soil-structure interaction in the interpretation of tests was detected by means of finite element models characterised by different accuracy in addressing the interaction problem. In the soil-structure interaction models the local site condition in correspondence of each bridge piers (resulting from geotechnical and geophysical investigations) were taken into account in the definition of the soil-foundation impedances. Comparison between the experimental results obtained from ambient noise measurements on the free-field and on the bridge deck permits the identification of both the predominant period of the site and the fundamental periods of the structure. In addition, comparisons between results obtained from the different numerical models with the measured dynamic response of the viaduct, in terms of fundamental frequencies and mode shapes, allow the identification of the contribution of different soil-structure interaction aspects such as the pile-soil-pile interaction, the radiation problem, the pile cap embedment as well as the variability of the soil stratigraphy along the longitudinal direction of the viaduct.

Effect of soil structure interaction on the response of R.C building to seismic loads, a case study

The evaluation of the response of reinforced concrete buildings subjected to seismic attacks, wind excitation or other dynamic loading types is essentially affected by the behaviour of the soil surrounding the foundation of the building. Many researchers have been studying the effect of soil structure interaction (SSI) over the last century, but there is still a controversy about the role of soil structure interaction (SSI) and its effect on changing the behaviour of structures. Commonly, designers assume that the base of the structure is fixed, but this approach is certainly not appropriate, for the reason that the stiffness and the damping of the soil are essential for a better designing of a structure. In this paper, the authors will discuss some proposed methods on taking account of soil-structure interaction that must be considered from the very beginning of the design process. In addition, an investigation about the dynamic response of a reinforced concrete structure subjected to seismic loads and designed by assuming the base coupled with discrete spring and dashpot elements, will be carried out.

Cost assessment of isolation technique applied to a benchmark bridge with soil structure interaction

Bridges are lifeline structures acting as an important link in surface transportation network and their collapse under seismic excitations affects social and civil functionality. Historical bridge seismic collapses under earthquake actions have proved the significant role of soil structure interaction. The paper aims at evaluating bridge protection and seismic strengthening applying isolation technique. It is based on the application of a Performance-Based Earthquake Engineering methodology, introduced by the Pacific Earthquake Engineering Research Center. The study presents a representative two—span bridge with several isolated configurations as affected by soil deformability. Isolation technique contribution is assessed in terms of costs quantities with peak ground acceleration levels. The study can be considered a first attempt to evaluate seismic effects of SSI by taking into account economic performance.

Stochastic Quantification of Soil-Shallow Foundation-Structure Interaction

This article highlights soil-structure interaction (SSI) effects on the seismic structural response accounting for uncertainties in the model parameters and input ground motions. A probabilistic Monte Carlo methodology was used to conduct approximately six million dynamic time-history simulations using an established rheological soil-shallow foundation-structure model. Considering the results yields outcomes that contradict prevailing views of the always beneficial role of SSI. In other words, the likelihood of having amplification in structural response due to SSI is large enough that it cannot be readily ignored. This research provides a significant first step towards reliability-based seismic design procedures incorporating foundation flexibility.

Nonlinear Dynamic Analysis of Reinforced Concrete Framed Structures Including Soil-Structure Interaction Effects

The role of soil-structure interaction on seismic behavior of reinforced concrete structures is investigated in this paper. Finite element approach has been adopted to model the interaction system, that consists of a reinforced concrete plane frame, soil deposit, and interface which represents the frictional surface between the foundation of the structure and subsoil. The analysis is based on the nonlinear characteristics of the materials and the elasto-plastic behavior of the frame members (beams and columns) is governed by a yield surface which is defined by ultimate strength of the axial force-bending moment interaction, while the cap model is adopted to govern the elasto-plastic behavior of the soil material. Results deduced from the dynamic analysis indicate that soil-structure interaction can have beneficial effects on structural behavior and this behavior is dependent on the characteristics of the soil and the interface conditions.

SEISMIC SOIL-STRUCTURE INTERACTION: BENEFICIAL OR DETRIMENTAL?

The role of soil-structure interaction (SSI) in the seismic response of structures is reex-plored using recorded motions and theoretical considerations. Firstly, the way current seismic provisions treat SSI effects is briefly discussed. The idealised design spectra of the codes along with the increased fundamental period and effective damping due to SSI lead invariably to reduced forces in the structure. Reality, however, often differs from this view. It is shown that, in certain seismic and soil environments, an increase in the fundamental natural period of a moderately flexible structure due to SSI may have a detrimental effect on the imposed seismic demand. Secondly, a widely used structural model for assessing SSI effects on inelastic bridge piers is examined. Using theoretical arguments and rigorous numerical analyses it is shown that indiscriminate use of ductility concepts and geometric relations may lead to erroneous conclusions in the assessment of seismic performance. Numerical examples are presented which highlight critical issues of the problem.