Consideration Of Soil-structure Interaction Research Articles

Seismic Response of RC Frame Building Considering Soil Structure Interaction

Foundation is a load transferring part of structure to soil. Recent trends have made replacement of conventional practice of isolated and eccentric footing with Mat foundation. Necessity to choose Mat foundation over conventional isolated footing is when the bearing capacity of soil is considerably low. However, consideration of properties of soil in contact with the foundation has not been applied in detail practice which is also called soil structure interaction (SSI) will significantly affects the performance of structures. Our study has used Winkler’s method to model the foundation soil as spring Moreover, three different buildings of five, seven and nine story were modeled using finite element method to incorporate the soil structure interaction effects. performance parameter to measure the performance of the structures was done using Roof displacement. This research reports the change in natural time period, roof displacement and base shear due to consideration of SSI and concludes with the urge of consideration of SSI in structural analysis and design.

Real-time assessment of tunnelling-induced damage to structures within the building information modelling framework

During the initial design phases of complex multi-disciplinary systems such as urban tunnelling, the appraisal of different design alternatives can ensure optimal designs in terms of costs, construction time, and safety. To enable the evaluation of a large number of design scenarios and to find an optimal solution that minimises impact of tunnelling on existing structures, the design and assessment process must be efficient, yet provide a holistic view of soil-structure interaction effects. This paper proposes an integrated tunnel design tool for the initial design phases to predict the ground settlements induced by tunnelling and building damage using empirical and analytical solutions as well as simulation-based meta models. Furthermore, visualisation of ground settlements and building damage risk is enabled by integrating empirical and analytical models within our Building Information Modelling (BIM) framework for tunnelling. This approach allows for near real-time assessment of structural damage induced by settlements with consideration of soil-structure interaction and non-linear material behaviour. Furthermore, because this approach is implemented on a BIM platform for tunnelling, first, the design can be optimised directly in the design environment, thus eliminating errors in data exchange between designers and computational analysts. Secondly, the effect of tunnelling on existing structures can be effectively visualised within the BIM by producing risk-maps and visualising the scaled deformation field, which allows for a more intuitive understanding of design actions and for collaborative design. Having a fully parametric design model and real-time predictions therefore enables the assessment and visualisation of tunneling-induced damage for large tunnel sections and multiple structures in an effective and computationally efficient way.

Influence of soil-structure interaction modeling on the behavior of multi-story plane steel frames with shallow footing foundations

Traditionally, structural analysis is based on the hypothesis that supports are indeslocable due to simplicity. However, the conventional design in which settlements of foundation elements are disregarded can lead to physical results that are incompatible with reality. This work aims to analyze the influence of the consideration of soil-structure interaction (SSI) on the responses of steel structural elements obtained by a static second order analysis. Furthermore, it is evaluated the responses obtained by different types of procedures for the consideration of soil stiffness in the structural analysis. Solid elements considering linearly elastic material parameters and spring elements based on the Winkler theory are employed. The analyses were performed with the commercial software SAP2000. Plane steel frames models were analyzed, either considering conventional supports or taking into account the soil-structure interaction. Shallow footing foundations are considered. Three frames with the same characteristics, but with a different number of floors were analyzed, showing the influence of the height increase and the building stiffness on the SSI results. It has been shown that the consideration of the effects of soil-structure interaction on structural analysis of buildings can have a significant influence on the stress distribution, displacements and structural behavior. In addition, it is concluded that the structural capacity of steel frames can be affected by the type of support adopted and by changes on the way the model considers soil deformation.

Soil-structure interaction in a base and mid-story seismically isolated building

The main goal of this study is to analyze the performance of seismic isolation systems by implementing isolation to the base and inter-story of the buildings together, in order to reduce the earthquake impact in multi-story buildings. In addition the soil-structure interaction for these cases are taken into consideration. An example building model was composed to observe the effect of base isolation and mid-story isolation numerically. Analyses were performed by using SAP2000 software. A five story building was used as an example structure. Investigations were carried out for six different combinations that are: fixed base buildings, buildings with soil-structure interaction, buildings incorporating single base isolation system with and without consideration of soil-structure interaction, buildings with base and mid story isolation system with and without consideration of soil-structure interaction. Two different earthquake motions were selected for time-history analysis. The results obtained from time-history analysis were discussed comparatively, for all the base-isolation cases including and excluding soil-structure interaction. It has been concluded that the seismic isolation application of the base and mid-story improves the seismic performance of the building. In addition, it has been observed that the soil-structure interaction affects the building seismic performances according to the reference ground type.

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.

Fuzzy probabilistic evaluation of soil-structure interaction effects on the soft-first-story structures

Even though the soil-structure interaction (SSI) has been investigated for long, less attention has been paid to the probabilistic framework. The present study used a fuzzy probabilistic approach to evaluate the effect of SSI on the nonlinear behavior of a soft-first-story structure with uncertain soil types. Sensitivity analysis was carried out to identify the relative importance of uncertainty parameters on the structural responses of the model structure. The analysis results showed that consideration of SSI in structures with relatively weak soil conditions could enhance the probability of irreparable damages in the structures. It was also observed that the variations in the weight density and shear wave velocity of soil were the most influential parameters in the structural responses.

Soil-structure interaction with time-dependent behaviour of both concrete and soil

As the consideration of soil-structure interaction is increasingly being incorporated into design practice, there is a need for solutions that consider the most relevant aspects of the behaviour of both the concrete and the soil, some of which are time-dependent. The present work introduces a model that suits both the structure and the foundation – including the supporting soil – allowing the coupled analysis of hardening on cure, creep, shrinkage and cracking of concrete, and consolidation of soil. Both the structure and the foundation are modeled as one-dimensional finite elements. The time-dependent behaviour of the concrete and soil is modeled using Kelvin chains. For the structural elements, a mixed finite element formulation is used. Validation tests were conducted in the proposed modeling, comparing its results with available experimental and analytical data. The study of a reinforced concrete continuous beam supported by foundations on consolidating clay considering the time-dependent behaviour of the materials showed considerable changes in the effects of the soil-structure interaction.

Effects of Soil on the Seismic Design of Long Span Steel Frames Using Contemporary Building Codes

Seismic excitations and other lateral dynamic distress cause the structure’s foundation to interact with the superstructure’s response. Consequently, the surplus stress distribution takes place. This disturbance in the lateral stiffness of the system can cause un-satisfaction with the adopted code provisions. In the above scenario, soil structure interaction of the Moment Resisting Frames (MRFs) becomes very crucial. This article deals with soil stiffness on the long-span MRFs designed with two modern building codes, namely Saudi Building Code (based on American Standards) and Eurocodes. High and medium ductility with parameter and spatial frame configurations are considered in this study. Each frame is analysed considering the foundation stiffness, calculated based on FEMA recommendations. Hence, a total of 18 cases are examined, conducting a modal response spectrum analysis. The period, top displacements, reactions, and damageability criterion for the analyzed frames are compared. It is shown that the consideration of SSI (Soil Structure Interaction) is paramount for frames with such spans, especially when subjected to high seismic forces.

Tuned mass dampers in wind response control of wind turbine with soil-structure interaction

The efficiency of tuned mass dampers (TMDs) in along-wind response mitigation of a wind turbine with consideration of blade coupling and soil-structure interaction (SSI) is investigated. The wind turbine tower is modeled as a multi-degree of freedom (MDOF) with three blades are connected as a MDOF system to the tower. The along-wind drag forces are generated using Shinozuka method. The effect of SSI is considered using frequency independent parameters. The equation of motion for the coupled system is numerically solved in time domain using the Newmark Beta method. In order to observe the changes in response of the system, the blades are subjected to rotating wind field to include the effects of the blade-tower interaction and rotor movement. The peak displacement, peak acceleration, root mean square (RMS) displacement, RMS acceleration, and power spectral density (PSD) of the wind turbine are the response quantities considered for comparative studies. Single TMD (STMD) and distributed multiple TMDs (d-MTMDs) are used to mitigate the wind response of the tower. Parametric studies are conducted to find the most suitable parameters (such as mass ratio, frequency bandwidth, and damping ratios) of the TMD schemes to increase the effectiveness of the strategy in the mitigation of the wind response of wind turbine with/without consideration of SSI. It is concluded that wind response of the wind turbine is amplified with inclusion of the SSI, blade-tower interaction, and rotor movement. In addition, it is concluded that the d-MTMDs are more effective and robust in wind response control of the wind turbine as compared to the STMD.

Comparison of Seismic isolation with isolator and Soil structure Interaction U-shaped metallic isolator and Soil structure Interaction

Soil condition is an important research area in earthquake engineering. In this work we evaluated the impact of soil-structure interaction (SSI) and U-shaped steel damper on the isolated response of the building base. Different soils for a seismic performance of multistory buildings are systematically compared and discussed. The soil’s physical state is divided into; hard soil, medium soil, and soft soil. It was compared with the U-shaped steel damper and there is noticeable difference between them. This study concludes that the use of steel damper shaped and SSI has been effective in minimizing structural response. It was observed that interaction of the soil structure provides some flexibility to the structure by increasing the structure’s displacements. Modeling base isolation along with consideration of soil structure interaction therefore leads to better structural response prediction.

A Review: Study of Integral Abutment Bridge with Consideration of Soil-Structure Interaction

Abstract Bridges are one of the most critical parts of transportation networks that may suffer damages against earthquakes. Also, seismic responses of most bridges are significantly influenced by soil-structure interaction effects. Taking out expansion joints in the bridges may cause many difficulties in design and analysis due to the complexity of soil-structure interaction and nonlinear behavior. The secondary loads on an IAB include seismic load, temperature variation, creep, shrinkage, backfill pressure on back wall and abutment, all of which cause superstructure length and stress variations in girder changes. The purpose of this study is to recognize the most effective parameters of analysis IABs. Findings show that the backfill material behind the IABs has a significant effect on the performance of IABs. Using a compressible material behind the abutments would enhance the in-service performance of IABs. Finally, behaviour of abutment may be greatly affected by thermal load and soil pressure. Thermal expansion coefficient significantly influences girder axial force, girder bending moment, and pile head/abutment displacement.

Effects of soil-structure interaction on base-isolated structures

Structural integrity and seismic protection of the buildings against earthquake have been challenging among structural engineers. Many studies have been devoted to development of seismic isolators to improve the seismic behavior of civil structures. This study presents the analysis of building structures with SAP2000 considering soil structure interaction and base isolation effects under El Centro. Four different models are analyzed including fixed base structure, base isolated structure, frame supported by spring representing the soil and structure with combined base isolation and spring. The seismic results are investigated in terms of displacement, shear force, axial force, moment and drift of the columns and beams. It was observed that the soil structure interaction provides some flexibility to the structure by increasing the displacements of the structure and imposing internal forces variation to the system. Therefore, modeling base isolation together with consideration of soil structure interaction leads to better prediction of structural response.

Unfavourable seismic behaviour of reinforced concrete structures due to soil structure interaction

The soil-structure interaction (SSI) effects can substantially alter the behaviour of structures during earthquakes. Implementation of SSI within the seismic analysis often leads to lower stresses in the structure and therefore a more economical design. The recently introduced provisions in European and American codes allow for this type of approach. However, consideration of SSI can also lead to the observation of unfavourable effects (undetectable in a fixed-base analysis) due to the modification of the structure’s dynamic properties. Examples of unfavourable effects include higher global displacements or story drifts, increases of the base or story shear forces, higher post-elastic demands in the structural members or the collision of adjacent buildings separated by an insufficient structural joint. These unfavourable effects can be related to various parameters such as the structural system (frames or shear walls), foundation type (shallow or piles), geometry of the foundation, height of the building, soil type, seismic input, presence of adjacent buildings, etc. Under these circumstances, the integration of SSI into the current structural design becomes essential. As the mathematical formulation of the phenomenon is very complex and involves many parameters, the definition of complete numerical models is difficult. The provisions in the codes are often general and do not give the practicing engineers clear modelling solutions. An analysis of the current situation in the field of SSI is carried out, with a focus on the design of reinforced concrete structures. Based on an extensive literature review, the unfavourable seismic effects and the main parameters that determine them are identified. Conclusions are drawn regarding the situations when SSI should be mandatory and on the different possibilities of implementing SSI in the structural design.

Optimum placement of supplementary viscous dampers for seismic rehabilitation of steel frames considering soil–structure interaction

SummaryIn this paper, the significance of soil–structure interaction (SSI) in optimal placement of viscous dampers in steel frames is studied. Optimal placement of dampers is determined with the purpose of achieving performance objectives at three hazard levels using genetic algorithm optimization. Endurance time method is used for seismic nonlinear response analysis of the fixed‐base and SSI included frames. The soil beneath the structures is considered as a homogeneous elastic half‐space, and the soil–structure systems are modeled by the substructure method. Results indicate that at low excitation intensities, consideration of SSI results in maximum drift ratio reduction at all stories of the frames. At higher intensity levels, more drift is observed in the upper stories of the soil–structure systems in comparison with the fixed‐base frames. Higher damping in the upper stories is required to optimally rehabilitate soil–structure systems as compared with the corresponding fixed‐base ones. In most of the frames, SSI leads to the reduction of total required damping. However, the optimal damper placement based on the analysis of fixed‐base frames can be unconservative due to changes in damping distribution patterns.

Seismic Behavior Analysis Considering Soil Structure Interaction of RC Multistory Buildings in Halabja City

Response of structures to seismic loads measures the degree of safety of the structures. In order for buildings to be under a more realistic circumstance, it is essential to consider the effect of Soil – Structure – Interaction (SSI) in the analysis of the building subjected to seismic loads. In this study, three samples of typical buildings with six, eight and ten stories are chosen with and without the effect of SSI using both equivalent static method and dynamic response spectrum analysis. For each method, the five different soil categories (SA, SB, SC, SD, SE) are examined to illustrate the effect of the foundation soil on the buildings subjected to a seismic load. The results show that no modifications can be observed in rock foundations with or without the consideration of SSI. On the contrary, the effect on SSI can increase the displacement in low stiffness soils particularly soil type (SE). Similarly the natural time period of the buildings increase significantly with decreasing the soil stiffness.&nbsp

Z-Transferred Discrete-Time Infinite Impulse Response Filter as Foundation–Soil Impedance Function for SDOF Dynamic Structural Response Considering Soil–Structure Interaction

This paper proposed a novel dynamic structural analysis of a single-degree-of-freedom system considering soil–structure interaction (SSI). The z-transferred discrete-time infinite impulse response filter serving as a foundation–soil impedance function to get a transfer function between the ground displacement and foundation shear was proposed first. The corresponding time history of the foundation shear caused by a specific input of ground displacement can be determined through the filter obtained, and the succeeding structural responses are then able to be found by the base force propagating function. Case studies comparing the structural dynamic response with and without SSI were carried out. Without consideration of SSI, there was an overestimation of structural displacement for the structure with a shorter period, but in contrast to that, an underestimation for the structure with a longer period was concluded based on the results obtained.

Soil-pile-structure interaction effects on high-rise building under seismic shaking

In this paper, study of the response (base shear, time period, storey drift, storey displacement) of a structure is done for the tall building including basement with fixed base and with pile foundation considering Soil Structure Interaction (SSI). Finite element based program ETABS2016 v16.1.0 is used for the analysis of the superstructure. Seismic analysis is done to get the dynamic response of superstructure for two types of model,one model is with fixed baseand second is Model with Winkler spring for Chhaya Center, Thamel, a high rise building with 14 story including double basements. Itisobserved with the consideration of Soil Structure Interaction (SSI). The soil is replaced by spring and assigned at joints. El Centro earthquake (1940) is used for time history analysis. The response obtained due to SSI effect is compared with fixed based model. Results of analysis presented include the comparison of natural periods, base shears, displacements and overturning moment. It is observed that the natural periods increase and the base shears decrease as the base become more flexible.

Seismic Response and Vulnerability Assessment of Representative Low, Medium and High-rise Buildings in Patna, India

The behavior of structures built on soft soil can be significantly different from the structures built on rocky soil. It is necessary to know the response of structures build on such soft soil conditions. Over the last few decades many researchers have studied merits and demerits of soil structure interaction (SSI). However the findings are contradictory in many aspects. Thus it may be necessary to assess vulnerability of structures founded on soft soil deposits. In this work, response and seismic vulnerability of representative low (3 storey), medium (6 storey) and high-rise (9 storey) reinforced concrete buildings in Patna, India are assessed. To obtain the seismic response of structures, representative reinforced concrete buildings with masonry infill walls are studied with and without SSI using SAP2000. It is found that consideration of SSI may provide underestimation of structural responses and vulnerability for the structures and site considered in this study.

Effect of dynamic soil–structure interaction on the seismic response of bridges with elastomeric bearings

The influence of soil–structure interaction (SSI) on the responses of an isolated bridge structure, subjected to seismic excitation, is investigated. The study considers the laminated rubber bearing and the lead rubber bearing for the seismic isolation of the bridge. The specific objective of the study is to evaluate the performance of the isolators and to investigate the effect of SSI on the seismic performance of the isolated bridge. A significant variation in the responses and the performance of the isolators are observed when the SSI is considered. It is concluded that consideration of SSI can lead to a more realistic structural modeling and more economical design of structures.

INFLUENCE OF THE SEISMIC EXCITATION FREQUENCIES CONTENT ON THE BEHAVIOR OF A TUNED MASS DAMPER IN LOW-RISE BUILDING CONSIDERING SOIL-STRUCTURE INTERACTION

The influence of the frecuency content of seismic excitations on the behavior of an optimal tuned mass damper (TMD) is studied in the context of a system with explicit consideration of soil-structure interaction. A stochastic analysis is made in the time domain for two random processes, one considering a broad bandwidth process (BBP) and other considering a narrow bandwidth process (NBP). A structure built over three different types of soil (soft, medium and hard) is considered. For the optimization of the TMD, the minimization of the ratio between the standard deviation of the displacement of the main structure with TMD with respect to a structure without TMD, is used as the target function. It is found that for seismic excitations with high frecuency content, the ratio of the TMD frequencies compared to the fixed base frequency of the structure approaches to 1 as the soil becomes more rigid. It is also observed that the TMD become tuned with the flexible base frequency for all soil types, producing perfect tuning for small mass ratios and detuning gradually for higher mass ratios. On the other hand, the TMD optimal damping ratio increases as the TMD mass ratio is higher, independently of the soil type. The TMD is more efficient for higher values of the TMD mass ratios, especially on soft soil. In structures built over flexible base, that are subjected to low frequency content excitations, the optimal TMD is tuned with the flexible base, independently of the type of soil and the fixed base period of the main structure. The TMD optimal damping is not sensitive to the flexible period for small mass ratios, and reaches its minimum value when it matches with the predominant period of the seismic event. On the other hand, the TMD reaches its maximum efficiency when it is tuned with the flexible period of the soil-structure system, and coincides with the predominant period of the seismic exitation and is higher on soft soil. A deterministic analysis is made using two seismic records, an artificial earthquake compatible with the Chilean code NCh2745 characterized by high frequencies content and other similar to the event in 1985 in Mexico, characterized by low frequencies content. It is seen that the optimal TMD is efficient controlling the response of the structure in all types of soil analyzed.