Soil-structure Interaction Studies Research Articles

Site Specific Non-Linear Ground Response Analysis and Soil Structure Interaction Study of Newly Constructed Dharahara Tower

This study investigates the seismic performance of the recently reconstructed Dharahara tower, a historically significant monument in Nepal that has experienced damage in past earthquakes and was completely destroyed in the recent Gorkha earthquake. Ground Response Analysis (GRA) and Soil-Structure Interaction (SSI) investigations are conducted to assess its structural behavior. GRA includes free field and structure-influenced analyses, with subsequent comparative assessment. Additionally, 3D non-linear finite element analysis is employed to derive equivalent spring constants representing soil and foundation characteristics, which are incorporated into the SSI analysis. These computed spring constants are used to model support conditions, allowing for an evaluation of the super-structural response. The study also employs non-linear dynamic analysis to compare structural responses between fix-based and spring-based models. The results indicate that the presence of the structure significantly influences surface wave motion amplification in GRA, resulting in peak ground accelerations (PGAs) that exhibit de-amplification in the free field and amplification in the presence of the structure. Furthermore, the introduction of an equivalent spring system in the soil-structure model changes the system's vibration period and damping characteristics, leading to enhanced dynamic response compared to the fixed-base model.

Numerical simulation of SSI free and forced vibration experiments on real scale structures of different stiffness

Time domain finite element (FE) analysis is a powerful tool for the study of Soil-Structure-Interaction (SSI) phenomena, but it requires a rigorous calibration of all aspects of the numerical model. This study presents three-dimensional (3D) FE analyses that are calibrated and validated against real scale free and forced vibration experiments on the prototype structure of EUROPROTEAS which is founded on soft alluvial sediments. The proposed calibration procedure exploits data recorded during experiments on structures with different structural stiffness, that mobilised SSI effects at different intensities. Particular focus is placed on the modelling of the soil-foundation interface, where zero thickness elastoplastic interface elements are used to allow foundation separation from the soil. A novel approach to simulate contact imperfections (gaps) between the foundation and the adjacent soil is proposed. The results demonstrate the significant impact of the interface gaps and soil nonlinearity on the response of the examined SSI systems, highlighting the importance of a rigorous model calibration.

Quantifying the Surface Strain Field Induced by Active Sources with Distributed Acoustic Sensing: Theory and Practice.

Quantitative dynamic strain measurements of the ground would be useful for engineering scale problems such as monitoring for natural hazards, soil-structure interaction studies, and non-invasive site investigation using full waveform inversion (FWI). Distributed acoustic sensing (DAS), a promising technology for these purposes, needs to be better understood in terms of its directional sensitivity, spatial position, and amplitude for application to engineering-scale problems. This study investigates whether the physical measurements made using DAS are consistent with the theoretical transfer function, reception patterns, and experimental measurements of ground strain made by geophones. Results show that DAS and geophone measurements are consistent in both phase and amplitude for broadband (10 s of Hz), high amplitude (10 s of microstrain), and complex wavefields originating from different positions around the array when: (1) the DAS channels and geophone locations are properly aligned, (2) the DAS cable provides good deformation coupling to the internal optical fiber, (3) the cable is coupled to the ground through direct burial and compaction, and (4) laser frequency drift is mitigated in the DAS measurements. The transfer function of DAS arrays is presented considering the gauge length, pulse shape, and cable design. The theoretical relationship between DAS-measured and pointwise strain for vertical and horizontal active sources is introduced using 3D elastic finite-difference simulations. The implications of using DAS strain measurements are discussed including directionality and magnitude differences between the actual and DAS-measured strain fields. Estimating measurement quality based on the wavelength-to-gauge length ratio for field data is demonstrated. A method for spatially aligning the DAS channels with the geophone locations at tolerances less than the spatial resolution of a DAS system is proposed.

Soil–basement interaction effects on the seismic response of tall buildings with basement levels

The need to build tall buildings has been increasing worldwide, creating new challenges in earthquake engineering and design. Many of the current analysis methods cannot be extrapolated beyond the definition under which they were established. Prior studies and existing seismic design guidelines have indicated that the current fixed-base hypothesis for evaluating the seismic response of structures is not sufficient to properly represent the boundary conditions and behavior of tall buildings with basement levels. Studies of soil-structure interaction (SSI) for tall buildings have, however, typically been inconclusive. It is not clear under which conditions consideration of soil-basement-structure interaction (SBSI) is necessary for the design of the superstructure, foundation, and basement levels and when it can safely be avoided. Given the rising demand, it is essential to evaluate the relation of global system variables such as the basement depth, structure height, and soil characteristics with the building’s response via numerical and experimental modeling. Therefore, an experimental-numerical approach is presented to better understand the seismic response of tall buildings with basement levels, considering explicit SBSI modeling. Chilean tall buildings and soil conditions are used as study cases, analyzed using nonlinear finite element analyses in conjunction with results from centrifuge experiments. The results show how seismic response parameters and modal characteristics, such as inter-story drifts, shear force, bending moment, natural frequencies, and damping ratios, change when SBSI is appropriately incorporated. The results point to the importance of considering soil-basement-interaction effects to evaluate the seismic response of tall buildings with basement levels and avoid unsafe estimations or the need for overdesign.

A State-of-the-Art Review on Soil-Structure Interaction

This paper provides an insight and the role of the dynamics soil structure interaction analysis depending upon the past studies. As a result of population boom and scarcity of land, buildings are constructed very close to each other. This is the major issue especially in the case of developing country where housing colonies are developing in the big cities as well as in the countryside, making the study of soil-structure interaction as an essential part of structural design process. The effect of soil, on which the structures stands, especially in the highly seismic zones, the dynamic behaviour of soil as well structure should be well known by the designer. The effects of structures standing in a close vicinity to each other is the main issue of soil-structure interactions as well as structure-soil-structure interactions. In this paper, various methods of soil-structure interactions carried out by various researchers in various region are reviewed.

Statistical analyses on the degree of influence of various assumptions in soil-structure interaction studies

The present paper investigates the degree of influence of various assumptions made in soil-structure interaction studies by statistical analyses. The variable under study is the displacement ratio between a fixed base single-degree of freedom system and a three-degree of freedom system, which takes into account soil-structure interaction. Both systems are subjected to the same translational base excitation. The equation of motion for each system is solved in the frequency domain. It is analytically proved and numerically validated, that the displacement ratio is independent of the excitation motion. Therefore, an extended parametric analysis is conducted by the implementation of the proposed equations for each degree of freedom in the frequency domain. The assumptions considered in the present paper refer to: (i) soft and stiff soil; (ii) frequency-dependency of foundation’s impedance functions; (iii) foundation’s inertia; (iv) slenderness ratio of superstructure; (v) soil profile. Correlation coefficients are calculated for all the combinations of the assumptions under consideration. The produced statistical results reveal the validity boundaries and the degree of influence of each assumption in soil-structure interaction studies.

Seismic response of nonlinear soil-structure interaction systems through the Preisach formalism: the Messina Bell Tower case study

In this paper the seismic response of linear behaving structures resting on compliant soil is addressed through the application of the Preisach formalism to capture the soil nonlinearities. The novel application of the Preisach model of hysteresis for nonlinear soil-structure interaction problems is explored through the study of the seismic response of a real structure. Through a harmonic balance procedure, furthermore, simplified nonlinear springs and dashpots are derived in closed form for a ready and accurate evaluation of the nonlinear soil-structure interaction response. The selected case study is the bell tower of the Messina Cathedral in Italy. The Bell Tower hosts the largest and most complex mechanical and astronomical clock in the world and it has been recently equipped by a permanent seismic monitoring system. A pertinent finite element (FE) model including the superstructure and the soil underneath, has been defined using authentic drawings and engineering design reports. The modal properties of the FE model have been compared with the experimental ones, identified from environmental noise recorded through the seismic monitoring system. Furthermore, the FE model has been validated by means of acceleration time histories recorded at different floors during two independent seismic events. A nonlinear incremental dynamic analysis of the Bell Tower has been also performed. The seismic response obtained by the complete FE analysis, has been compared with the proposed Preisach lumped parameter model, assembled with nonlinear springs and nonlinear dashpots. The results are well in agreement, offering an alternative promising strategy for the nonlinear soil-structure interaction studies.

Soil structure interaction studies on Krishnaraja Sagara Bridge, Mysuru

Roads are the lifelines of modern transport, and bridges are an integral part of the system. They are susceptible to failure if their structural deficiencies and geotechnical aspects are unidentified. A large number of bridges constructed around the world were designed during the period, when bridge codes authorities didn’t think about seismic design provisions, or when these provisions were insufficient according to the present standards. Some of the earthquakes which have caused severe damage to a considerable number of bridges that had little or no design consideration to seismic resistance and poor geotechnical investigations leads to huge loss of lives and property.An attempt is made to study the effect of various kinds of soil, on soil structure interaction due to seismic forces. For the study purpose, Krishna Raja Sagar downstream bridge situated near Mysore, Karnataka is considered, as the bridge has some vibration problems. The bridge is modelled using MIDAS Civil software. The bridge is a T-beam bridge of total length 470.4 m and consists of eight bays, and each bay measures around 58.8 m. Each bay has 3-spans of 18 m, 22.8 m, and 18 m respectively. The deck is supported by circular piers of 1.2 m dia.Initially, the available site specific soil stiffness is considered and later the stiffness of soil is varied considering soft, medium and hard soil condition by varying, Young’s modulus and Poisons ratio. Gezeta’s soil stiffness model is used to obtain the soil stiffness. Eigen value analysis and nonlinear static analysis are carried out to check the seismic performance and behavior of bridge for various soil conditions. The natural frequency of the bridge lies between 4 Hz and 5 Hz for initial three modes of vibration considering soil structure interaction. It is found that the existing vibrations of the bridge are in the acceptable range.

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.

Soil–Structure Interaction Study on 3D SMRFs of Indo-Gangetic Plain Using Resonant Vibration Tests

ABSTRACT This study investigates the soil–structure interaction (SSI) behavior of low- to medium-rise steel moment-resisting frames (SMRF) resting on loose Ganga sand through a series of resonant vibration tests. Three-dimensional models of a three-story and a six-story structure are used for this purpose. Horizontal harmonic excitations, tuned to the first two natural frequencies of the structures, are applied using a modal mass shaker. Afterwards, a numerical model is developed where the SSI is modeled using discrete Winkler-type springs, and the experimental results are compared with the analytical ones. The study indicates that the floor acceleration and column moment decrease significantly (as much as 50% and 74%, respectively) when the structure is placed on the soil bed compared to the fixed base condition. The estimated energy dissipation is up to 23% through foundation rocking vibration. Furthermore, the deformation and moment distribution profiles are observed to be very sensitive to the exciting frequency, indicating the importance of frequency characteristics of input motions while characterizing the dynamic behavior of multi-story SMRFs.

Monotonic and dynamic properties of riverbed sand and hill-slope soils of seismically active North-east India for ground engineering applications

The stress–strain characteristics of soil under monotonic loading conditions and the dynamic properties of soils under cyclic loading are necessary for foundation engineering, ground response analysis and soil structure interaction studies. In the absence of site/region-specific properties, it is a common practice to use representative parameters based on the index properties of soil and available standard correlations. Such correlations might be inadequate for regional soils of varying index properties. Based on monotonic and cyclic triaxial tests, this study reports the monotonic and dynamic soil properties of the prevalent soils from the northeastern region of India, namely the cohesionless, cohesive and silty-sandy soils. It is observed that monotonic response of cohesionless soil is mostly influenced by the initial relative density, while the response of cohesive and silty-sands are primarily influenced by the effective confining pressure and degree of saturation. The cyclic triaxial tests revealed that, irrespective of the soil type, the strain-dependent modulus reduction and especially the damping ratio curves are noticeably different from available standards. The study highlights the importance of identifying the site/region specific soil properties for their usage in GRA and SSI applications.

The integral bridge design concept for the third runway at Heathrow, UK

The Heathrow expansion project proposals comprise major works around Heathrow airport to allow the construction of new terminal buildings and the third runway. Owing to the critical nature of uninterrupted operation of both runway and the M25 motorway, the preliminary design had to be developed to minimise maintenance operations. At over 140 m in the total length, the adoption of an integral bridge of this length is in excess of most integral bridges in the UK, particularly where full-height abutments are being utilised. The maximum predicted expansion length also lies outside the limit equilibrium method set out in PD6694-1. As such, it was agreed that a full soil–structure interaction study should be carried out to assess the impacts of the structural behaviour of the bridge and its abutments. This paper looks at the calibration work for that study, the derivation of the earth pressures behind the walls, the behaviour of the abutment and how this compares with the predictions set out in PD 6694-1.

Study of soil structure interaction on basement wall with variants in distance and depth of the basement on soil class SE

The function of the basement is to carry the weight of the upper structure into the soil and to resist lateral loads around the basement wall. One aspect of geotechnical engineering that often a problem in basement wall planning is the determination of lateral ground pressure in the basement wall due to earthquake which must be held by the basement wall. In this study, an analysis of the effects of local soil conditions due to dynamic loads is done through analysis of soil-structure interaction. The analysis is done by modeling the local soil with variations in basement depth and the adjacent basement distance to get the lateral pressure distribution due to dynamic load. The analyzed soil conditions are considered homogeneous at land sites SE (soft soil) with the dynamic load input from earthquake loads uses a 10% probability of exceedance in 50 years (500 years). The most influential parameter for soil displacement is the distance of the basement and then the depth of the basement. The most influential parameter on lateral forces is the depth of the basement followed by the distance of the basement.

A new full‐scale testbed for structural health monitoring and soil–structure interaction studies: Kunming 48‐story office building in Yunnan province, China

This paper introduces a new and unique full-scale testbed site for structural health monitoring and soil–structure system identification studies being developed in southwest China. The site is a 48-story skyscraper with an extended four-level basement, supported by piles, located in Kunming, the capital of Yunnan Province. Located in the diffused zone of collision of the Indian and Eurasian tectonic plates, Yunnan is one of the most active seismic areas in mainland China. The final sensor deployment will consist of 43 triaxial accelerometers (129 channels) and one weather station. The accelerometer array comprises (a) a structural array of 25 accelerometers installed at 10 levels aboveground, (b) a basement array of 14 accelerometers distributed in the first and fourth basements, and (c) two borehole arrays installed close to the basement perimeter wall, each with one accelerometers at the surface and another one at 50-m depth, which is the depth reached by the piles. With such dense instrumentation of structure, basement, and pile foundation, this site will be the first permanently instrumented full-scale testbed to enable identification of a soil-foundation–basement-structure system and validation of many assumptions commonly made in the prediction of the soil–structure interaction effects. A high-performance wired local area network has been installed in the building, featuring a Precision Time Protocol-enabled time synchronization and real-time remote access over the Internet. The site will be fully operational in late spring of 2020. Results of preliminary system identification of the structure from ambient vibration test data are presented.

Validation of a finite element modelling approach on soil-foundation-structure interaction of a multi-storey wall-frame structure under dynamic loadings

Validated numerical approaches are very important in dynamic studies of soil-structure interaction. Experimental outputs of physical models are required to validate the numerical approaches. Testing and analysis of an experimental scaled model is economical in comparison with investigating real size structures. However, a set of scale factors are required to model a full-scale structure accurately as a scaled model in a laboratory environment. In this paper, the scaling procedure and design of a scaled multi-storey concrete wall-frame structure with a scale factor of 1:50 are addressed. A specially selected dry sand with round shaped particles and specific grain size distribution was adopted in this study. A flexible soil container was designed and built to represent the soil boundary behaviour during time-history seismic excitations. The experimental investigations were divided into three different stages: fixed based structure without soil interaction; soil container without any structure; and, a structure with raft and pile foundations in the soil container. Finally, the same experimental stages were modelled numerically using a 3D finite element software. The results showed that the finite element simulations produced a good response when compared with the experimental results and these numerical models are suitable to be employed for further dynamic studies.

Soil Structure Interaction Effects on R C Structures Subjected to Dynamic Loads

From the past studies, every engineering structure was designed to withstand all external and internal forces applicable to the structure. For this many design methods are implemented and different techniques are found manually, experimentally and practically. One of the parameters which influence the analysis results is, support condition of the structure. Assuming fixed or pinned support in regular analysis of structure considering soil interaction with foundation may not produce accurate results as support condition differ by type of soil ie., loose, medium or hard & their characteristics. So, there is need to study about structural interaction with soil and their outcome deeply. Now a day’s soil structure interaction studies are playing major role in the analysis & design of structures. Many studies are carried out on structure interaction of soil considering seismic or lateral forces. This paper reviews the studies carried out on structural interaction with soil and its impacts on various reinforced concrete buildings subjected to dynamic loads.

Optimum lateral extent of soil domain for dynamic SSI analysis of RC framed buildings on pile foundations

This article describes a novel approach for deciding optimal horizontal extent of soil domain to be used for finite element based numerical dynamic soil structure interaction (SSI) studies. SSI model for a 12 storied building frame, supported on pile foundation-soil system, is developed in the finite element based software framework, OpenSEES. Three different structure-foundation configurations are analyzed under different ground motion characteristics. Lateral extent of soil domain, along with the soil properties, were varied exhaustively for a particular structural configuration. Based on the reduction in the variation of acceleration response at different locations in the SSI system (quantified by normalized root mean square error, NRMSE), the optimum lateral extent of the soil domain is prescribed for various structural widths, soil types and peak ground acceleration levels of ground motion. Compared to the past studies, error estimation analysis shows that the relationships prescribed in the present study are credible and more inclusive of the various factors that influence SSI. These relationships can be readily applied for deciding upon the lateral extent of the soil domain for conducting precise SSI analysis with reduced computational time.

An Evaluation of Pile-Raft Interaction in Cohesive Soils using 3D Finite Element Method

This paper presents the results of a numerical study of soil-structure interaction in a piled-raft foundation system in clay soil by reviewing the deformation and load transfer mechanism of the piled-raft foundation system. ABAQUS was used to evaluate the interaction in the system, while a Mohr-Coulomb constitutive model was chosen to model the clay soil. Verification of the model was conducted by comparing the simulation result to an experimental laboratory result. The verification result showed that the model used in this research agreed well with the experimental laboratory research. Subsequently, a parametric study was performed by varying the pile spacing, raft size, pile length, and raft thickness. A parametric study was conducted on very stiff and hard clays. This study concludes that the load transfer mechanism in a piled-raft foundation system between the pile and raft foundation occurs after the pile reaches its ultimate capacity and is in the plastic zone.

Discussion of “Implementation of Soil Pressure Sensors in Large-Scale Soil-Structure Interaction Studies” by L. Keykhosropour, A. Lemnitzer, L. Star, A. Marinucci, and S. Keowen, This article was published in Geotechnical Testing Journal, Vol. 41, No. 4, 2018. [DOI: 10.1520/GTJ20170163

Discussion of “Implementation of Soil Pressure Sensors in Large-Scale Soil-Structure Interaction Studies” by L. Keykhosropour, A. Lemnitzer, L. Star, A. Marinucci, and S. Keowen, This article was published in <i>Geotechnical Testing Journal</i>, Vol. 41, No. 4, 2018. [DOI: 10.1520/GTJ20170163

Closure to Discussion of “Implementation of Soil Pressure Sensors in Large-Scale Soil-Structure Interaction Studies”

Closure to Discussion of “Implementation of Soil Pressure Sensors in Large-Scale Soil-Structure Interaction Studies”