Soil-structure Interaction Research Articles

Case study of adjacent integral bridges supported on continuous secant piled walls

Integral bridges are often the preferred way of construction for short and medium span bridges in the UK. However, the behaviour of integral bridges is influenced by complex soil-structure interaction behaviour that may be cumbersome to predict and analyse when dealing with unusual structural arrangements. This paper presents a case study for the design of two single span bridges carrying a roundabout over a dual carriageway, supported on continuous secant piled walls. One of the bridges is fully integral while the adjacent structure is articulated at one end due to its skew. An alternative detail for the articulated end is proposed, to eliminate soil pressures and settlements at the back of the abutments as well as reduce the risk of water ingress to the bearings. The complex nature of the structural arrangement presented analytical challenges, that were solved by developing an advanced modelling approach, exploring two proposals. The first is to evaluate the geotechnical model for a range of imposed top of abutment displacements from the onset. The second, using unique non-linear springs and derived P-Y curves describes the more realistic variable nature of soil-structure interaction over the length of the walls leading to reduced soil pressures enhancing design feasibility.

Seismic Design of Underground Structures’ Vulnerability – Review.

This article examines the vulnerability of underground structures to seismic activity, with a particular focus on design and mitigation strategies. Underground buildings are essential to the development of modern infrastructure and must include tunnels, subway stations, and storage facilities. Because of its deep location, seismic design and earthquake performance are both more challenging. In this study of seismic susceptibility, topics such as ground motion characterization, soil-structure interaction, structural reaction, and failure mechanisms specific to underground structures are discussed. According to the paper, their susceptibility can be affected by geotechnical conditions, the kind of structures they have, and the construction methods that are used. The seismic stability design and analysis process involves measuring the dynamic response of subsurface structures to seismic loads. The goal is to keep earthquake and seismic forces from toppling structures in any way that is possible. Advanced analytical and numerical approaches are used in seismic stability design. Some examples of these methods are finite element analysis (FEA), discrete element modeling (DEM), and the boundary element method (BEM). In addition to that, it investigates contemporary methodologies for assessing seismic vulnerability as well as international design standards. In addition, seismic retrofitting and design advances for underground structures are analyzed and discussed in this paper. This document compiles and evaluates previous research to gain an understanding of the seismic susceptibility of subsurface structures and to promote more seismic engineering research on this extremely important topic.

Application research on nonlinear partitioned analysis of soil-structure interaction method of seismic response for seawater-seabed-structure.

The analysis of seismic response in marine engineering structures is pivotal for guaranteeing their seismic safety. Such analyses are intricate due to the complexity of fluid-structure and soil-structure interactions. This paper introduces a unified computational framework for wave motion within a water-saturated seabed-bedrock system, employing the Davidenkov model and a modified Massing rule to characterize the nonlinear properties of the saturated seabed. A comparative analysis is conducted between the nonlinear responses of marine sites subjected to linear and nonlinear free-field inputs, with a specific focus on the seismic response of bridges under seawater-seabed-structure interaction. The study demonstrates that the modulus of a nonlinear saturated seabed diminishes, leading to a decrease in the wave impedance ratio between the saturated seabed and bedrock. Consequently, the reflection and transmission coefficients from the bedrock to the saturated seabed increase, amplifying the seismic response. For deepwater bridges, under harder site conditions, the abutment's bottom response is largely insensitive to increasing water depth, whereas the shear at the abutment's base diminishes with increasing water depth. The proposed method is validated through two case studies, with an examination of the impact of saturated sites on the analysis results.

Advanced nonlinear soil-structure interaction model for the seismic analysis of safety-related nuclear structures

AbstractThis article proposes an advanced nonlinear soil-structure interaction methodology, for the seismic analysis of a nuclear structure. To do so, a study is performed on a nuclear reinforced concrete structure considering the effects of the nonlinearity due to the sliding and rocking at the soil-structure interface, under a Beyond Design Basis Earthquake. A tridimensional numerical model based on the Finite Element Method is developed for the structure and the soil. The model of the structure considers composite materials to describe all the structural members, taking full advantage of the modelling capabilities of the finite element method. The soil layers are modelled assuming their degraded properties due to the propagation of the seismic ground motion. An innovative approach to achieve spectral matching at the surface of the FEM soil model after propagation from the bedrock has been successfully implemented. The seismic analysis on the structure has been performed by considering three hypotheses for the contact between soil and structure: fixed-base, fixed contact and sliding-rocking contact. Insights are provided after comparing floor spectra for the contact approaches assessed in this research, calculated at the systems and components’ locations at the nuclear structure. Finally, a statistical approach for the soil properties allows to study the effects of these uncertainties on the structural response.

Investigating Calcareous and Silica Sand Behavior at Material Interfaces: A Comprehensive Study

Abstract This study centers on the crucial determination of the mobilized friction angle between soil and various materials, including steel and concrete, to enhance the modeling of soil-structure interaction. The primary objective of the current investigation was to assess the interfacial friction between calcareous and silica sands when interacting with concrete or steel surfaces. To achieve this, direct shear tests were conducted to examine the impacts of relative density (Dr), surface roughness (Rn), and shearing direction. The test results reveal that the shear strength of calcareous sand surpasses that of silica sand when considering a specific Rn. Furthermore, the interface friction of both sand types escalates with an increase in normal stress and Rn, with higher values observed in interactions with steel plates. Notably, the friction angle ratio (the interaction friction angle over the pure sand friction angle) demonstrates minimal dependence on the sand type. The most pronounced divergence in the friction angle ratio is evident at the maximum Rn value, which increases alongside Rn values for both calcareous and siliceous sands. With increasing Rn values, the maximum shear strength, contingent on normal stress and relative density, also rises. The influence of relative density on the interaction friction angle diminishes with escalating surface roughness.

Three-Dimensional Numerical Analysis of Seismic Response of Steel Frame–Core Wall Structure with Basement Considering Soil–Structure Interaction Effects

In recent years, numerous studies highlighted the crucial role of the soil–structure interaction (SSI) in the seismic performance of basement structures. However, there remains a limited understanding of how this interaction affects buildings with basement structures under varying site conditions. Based on the three-dimensional (3D) numerical analysis method, the influence of the SSI on the seismic response of high-rise steel frame–core wall (SFCW) structures situated on shallow-box foundations were investigated in this study. To further investigate the effects of the SSI and site conditions, three types of soil profiles—soft, medium, and hard—were considered, along with a fixed-foundation model. The results were compared in terms of the maximum lateral displacement, inter-story drift ratio (IDR), acceleration amplification coefficient, and tensile damage for the SFCW structure under different site conditions, with both fixed-base and shallow-box foundation configurations. The findings highlight that the site conditions significantly affected the seismic performance of the SFCW structure, particularly in the soft soil, which increased the lateral deflection and inter-story drift. Moreover, compared with non-pulse-like ground motion, pulse-like ground motion resulted in a higher acceleration amplification coefficient and greater structural response in the SFCW structure. The RC core wall–basement slab junction was a critical region of stress concentration that exhibited a high sensitivity to the site conditions. Additionally, the maximum IDRs showed a more significant variation at incidence angles between 20 and 30 degrees, with a more pronounced effect at a seismic input intensity of 0.3 g than at 0.2 g.

Dynamic analysis of a pedestrian bridge using monitoring and computational techniques

Soil-structure interaction (SSI) represents an important parameter when analyzing the dynamic behavior of bridges, considering the combined effects of soil, foundation, and structure to ensure an adequate structural representation. This paper applied a computational modeling strategy associated with soil-structure interaction methodology to represent the dynamic behavior of a timber-concrete pedestrian bridge of the Polytechnic School of the University of São Paulo. The computational models were validated and calibrated using monitoring results from an extensive structural health monitoring campaign. The bridge monitoring program was characterized using embedded sensors and remote monitoring technology: ground-based radar interferometry and video motion amplification. The instrumentation results were compared to establish the capabilities and advantages of this novel remote monitoring technique. The experimental results obtained from free and forced vibrations in the asset served as a basis for validating the developed computational model and allowed the evaluation of the asset behavior in service for different loading conditions. This paper emphasizes the importance of considering an SSI approach to represent the bridge dynamic behavior more accurately, enabling the use of more reliable numerical models to assess the bridge structural responses throughout its life-cycle.

Attenuation of bulk waves using locally resonant soil-coupled metabarriers

Abstract Low frequency ground-borne vibrations generated by transport infrastructure are one of the most serious causes of disturbance to the general population. One possibility to reduce this problem is to use the wave filtering properties of elastic metamaterials. However, their integration in the soil complicates the prediction of their response, and the influence of soil-structure interaction needs to be correctly evaluated for an efficient design. The aim of this work is to experimentally evaluate the efficiency of metamaterial trench barriers set in soil in attenuating vibrations, using low-frequency local resonance mechanisms. A lab scale model is proposed comprising different resonating structures and a cylindrical encasement is adopted to couple the structure to the soil. The influence of various parameters is evaluated, such as metamaterial structure, geometrical characteristics of the resonator, and constituent materials. Finite Element simulations are used to develop a suitable design, analysing mode shapes and resonance frequencies of structures with and without the surrounding encasement. Experimental modal analysis is then performed on the corresponding fabricated samples, providing both model validation and out-of-soil mechanical characterization. Finally, vibration transmission loss measurements are performed in a setup in which different resonant metamaterial barriers are embedded into the soil sample, allowing the evaluation of barrier performance. Results indicate that the metamaterial structures provide good attenuation of vibrations in selected intervals in the low to high frequency range (1–5 kHz), demonstrating the feasibility of the approach in a scaled sample. Preliminary data regarding the structures providing preferable design characteristics is also obtained. These results can be useful for the design of trench barriers scaled to large dimensions in more realistic applicative settings.

Laboratory Study of Interface Friction between Sand and Steel Surfaces

Abstract In this study, results have been reported from a series of laboratory tests to determine the interface friction angle of steel surfaces with sand through modified direct shear testing. For completion, steel surfaces with different surface geometry to replicate the roughness have been slid against various sands compacted at different relative densities under both dry and wet conditions. The standard square shape direct shear box has been modified into circular and rectangular boxes to sufficiently enhance the contact area and to subsequently quantify its effect on interface friction angle. A mild steel interface of smooth and rough texture with a groove depth of 0.2 mm and tipping at an angle of 90° has been used in this study. The analysis of results revealed that the interface friction angles obtained from the standard direct shear box agree closely with those obtained from both modified rectangular and circular shear boxes. However, the ratio of the interface friction angle from the modified apparatus and soil’s angle of internal friction significantly depends upon the roughness of the surface in contact with the sand, its median particle size, and is independent of the effects of box size, soil’s relative density, and dry or wet condition. A comparison between existing well-accepted guidelines and current observations has been presented for use by the practicing engineers dealing with soil-structure interaction.

A 4D Soil-Structure Interaction Model Testing Apparatus

Abstract A new three-axis loading frame has been developed to enable real-time visualization of in-situ soil and rock structure interactions via X-ray tomography during small-scale model testing. The constructed frame is capable of performing a wide range of small-scale 1g tests and can accommodate monotonic and cyclic actuation under both load and displacement control. The compact size of the system enables remote multi-axis operation from within an X-ray cone-beam scanning bay, a capability which is owed to a comprehensive design process. Design and fabrication involved a blend of physical and numerical experiments to assess suitable construction materials and performance. In this scope, the new equipment is discussed and its capability is showcased.

Dynamic model identification of the medieval bell tower of Casertavacchia (Italy)

The structural safeguard of tangible cultural heritage, monuments in particular, needs a multi-disciplinary approach involving historical–critical analysis, survey, in-situ and laboratory testing to provide a comprehensive knowledge on the object under investigation and build a structural model representative of the current state of the monument. In this paper, this approach is applied to the case study of the bell tower of San Michele Arcangelo cathedral in Casertavecchia (Italy). The historical–critical analysis was fundamental to understand the evolution of the tower over the centuries. Material tests were complemented by ambient vibration testing (AVT) which allowed for a complete characterisation of frequencies and mode shapes for the bell towers. A further model identification procedure was carried out to exploit the amount of information gathered within the documental and experimental activities and set up a reasonably accurate numerical model. The activities described in this paper highlight (a) the importance of correctly representing all substructures present in the monument, possibly hidden and built in different historical periods; (b) the possibility offered by model identification procedures to separate identifiable from less significant parameters, as well as selecting the best model in terms of representation complexity; (c) the effect of soil-structure and structure-structure interaction on the modal behaviour of the monument. In particular, the identification analyses without considering the inner concrete frame are consistently characterised by higher values of ωf and ωMAC compared to the analogous analyses in which all substructures were included. The best fit with the dynamic data is obtained by introducing deformable structure-soil connection while the effect of lateral constraints is hardly captured by the utilised setup.

Comparative Study of Semi-Active Control Effectiveness of Structures on Soft Soil Using MR Damper: Shaking Table Investigation

The effect of soil-structure interaction (SSI) cannot be neglected in semi-active vibration control of structures located on soft soil. To investigate the mitigating effect of magnetorheological (MR) damper on the semi-active control of structures considering the SSI, shaking table tests were conducted to evaluate the performance of the MR damper-based semi-active control system for structures on soft soil. In addition to a novel fuzzy control method based on online learning deep neural network (OL-DFNN), various control strategies, including passive OFF, passive ON, ON–OFF and deep neural network fuzzy control (DFNN) were systematically evaluated. The test results showed that the OL-DFNN control method exhibited superior adaptability to varying ground motion and structural dynamic characteristics compared to the other control methods. In particular, the OL-DFNN controller effectively mitigated the peak displacement and root mean square displacement, outperforming the passive OFF, passive ON, ON–OFF and DFNN control strategies. The test results highlight the effectiveness of the OL-DFNN control method in addressing the challenges posed by dynamic and time-varying characteristics in structural vibration control systems considering SSI.

Seismic Vulnerability Assessment of the Cliff-Attached Buildings Equipped with Energy Dissipation Devices Under Obliquely Incident Seismic Waves

Cliff-attached structures are structures attached to slopes and connected tightly, which is particularly complex to analyze due to the foundations’ unequal grounding and the lateral stiffness’ irregularity. In rare earthquakes, seismic waves are usually obliquely incident on the foundation at a certain angle. Therefore, it is not appropriate to consider only seismic waves’ vertical incidence, and it is necessary to consider multi-angle oblique incidence. In this paper, based on the theory of viscous-spring artificial boundary and the principle of equivalent nodes at the interface of oblique incidence of ground shaking P-waves, and combined with the dynamic properties related to Buckling-Restrained Brace, the numerical models of slopes and two kinds of cliff-attached structures considering the slope amplification effect and soil-structure interaction are established. The dynamic response of the obliquely incident seismic waves under the action of the cliff-attached vibration reduction structure is studied in depth, and the additional effective damping ratios of the nonlinear energy-dissipated units based on the deformation energy are compared and analyzed. It is shown that under the four oblique incidence angles of incidence (compression waves in the vertical plane) studied in this paper, the seismic dynamic response and damage degree peaked at an angle of incidence of 60°, with a tendency to increase and then decrease with increasing angles of incidence. The ability of an energy-dissipating vibration reduction device to change structural vibration characteristics decreases with an increase in incidence angle. The difference between the total strain energy of the structure in the X-direction (Transverse slope direction) and Y-direction (Down-slope direction) and the total energy dissipation of the dissipative components is obvious, with the X-direction being about 10 times that of the Y-direction.

Comparative Analysis of Soil-Piles Structure Interaction of Framed Structure

This study presents a comparative analysis of a 15-story building with two foundational approaches: a fixed- base foundation and a pile foundation incorporating soil- structure interaction (SSI) in sandy soil conditions. The research investigates the dynamic behavior of each foundation type under varying conditions, specifically examining the effects of different pile spacings and relative densities of sandy soil on the building’s fundamental frequency, time period, lateral displacement, and overall structural stability. The SAP2000 software is used for numerical study. Key Words: Soil-Structure Interaction (SSI), frequency, time period, displacement, Lateral Displacement, Seismic Analysis, G+14, SAP2000, sandy soil

Analysis of Soil-Structure Interaction of Framed Structure

This study examines the soil-structure interaction (SSI) effects on the seismic behavior of G+7 and G+12 reinforced concrete buildings. Using finite element modelling in SAP2000, we assess key seismic parameters, including base shear, time period, lateral displacement, and footing settlement, across three soil types: soft, medium, and hard. This comparative analysis provides insights into how building height and soil flexibility influence structural stability, suggesting optimal design considerations for enhancing earthquake resilience. Key Words: Soil-Structure Interaction (SSI), Base Shear, Lateral Displacement, Seismic Analysis, G+7, G+12, SAP2000, Soft Soil, Medium Soil, Hard Soil.

Incorporating soil‐structure interaction into simplified numerical models for fragility analysis of RC structures

AbstractSimplified building models are a valuable option for seismic assessment at the regional scale. These models often use calibrated springs to model column behaviour, and recent advances have made them suitable for capturing torsional response in Reinforced‐Concrete Moment‐Resisting‐Frames. Nevertheless, their validation is typically achieved using fixed‐base models, which do not include the influence of soil‐structure interaction (SSI). This study introduces a novel approach to quantify the accuracy of a recently developed simplified model while accounting for dynamic SSI, using a newly implemented, refined 3D Finite Element non‐linear soil model in OpenSees. The accuracy of the simplified structural model is assessed by comparing the results of non‐linear dynamic analyses with those of a refined model in terms of (i) a peak structural demand parameter such as the interstorey‐drift ratio and (ii) fragility curves computed from cloud analysis and accounting for collapse cases. The study presents details of the proposed refined approach for 3D soil modelling in OpenSees, focusing on implementing free‐field boundary conditions and structure‐to‐soil connections. Results show that the accuracy of the simplified model is maintained, even in the presence of SSI, and it successfully captures the overall structural response measured at peak demand. For the proposed case study, the difference between the simplified and refined models’ fragility curves’ medians is 4% and 2% for fixed and SSI models, respectively. The simplified structural model, combined with the refined soil model for SSI effects, presents an innovative and conservative, yet computationally efficient, alternative for seismic risk analysis, even in the presence of structural irregularity.

Shaking table test and numerical simulation of rocking wall frame structure considering dynamic soil-structure interaction

This study investigates the seismic response of a rocking wall frame structure considering dynamic soil-structure interaction (DSSI) through shaking table tests. A comparison with conventional frame structures and structures with fixed-base foundations is made to examine the influence of DSSI effects on various aspects including structural damage distribution, dynamic characteristics, and floor responses. Test results indicate that the presence of a rocking wall reduces structural responses across different site conditions, although the reduction is less significant under soft soil conditions compared to fixed-base foundation conditions. Overall, DSSI diminishes the mitigating effect of the rocking wall on the maximum structural response. Furthermore, a three-dimensional finite element model of the shaking table test is established. The numerical model employs the equivalent linear method to simulate the soil's nonlinear behavior and incorporates the concept of the rocking wall. Comparative analysis between experimental and simulated results demonstrates that the model effectively predicts the dynamic response of the rocking wall frame structure in DSSI systems.

Seismic Response of Open Ground Story Reinforced Concrete Buildings, Considering with Soil-Structure Interaction

This study investigates the seismic behavior of open-ground story (OGS) reinforced concrete buildings with soil-structure interaction (SSI) using SAP2000. The study mainly focused on mid-rise (8-storey) and low-rise (4-storey) OGS buildings, incorporating different masonry infill materials such as brick, concrete blocks, and autoclaved aerated concrete (AAC) blocks. Selected ground motions from the Bhuj, El Centro, and Chi-Chi earthquakes were utilized to simulate varying seismic intensities and frequency content. Critical parameters such as top-story displacement and inter-story drift are analyzed to assess the structural safety and serviceability of RC buildings. The results demonstrate that both OGS coupled with SSI and masonry infill type significantly affect the displacement and drift, with mid-rise buildings showing more pronounced impacts. Furthermore, ground motion characteristics are critical in producing different response patterns. The study highlights the importance of considering SSI, infill materials, and ground motion characteristics in the design of OGS buildings to enhance earthquake resilience and reduce seismic damage.

Seismic nonlinear interaction and uplifting effects between the nuclear island building and soil

Since the Fukushima nuclear accident, seismic design requirements have increased, necessitating a more refined evaluation of base uplift for weakly anchored nuclear island buildings. The elevated cooling water over 3000 t is a distinguishing feature of third-generation reactor buildings (RBs). To assess potential safety-adverse coupling effects, seismic wave propagation process through viscoelastic soils, discontinuous interfaces, and sloshing water was analysed. To facilitate nonlinear systematic simulation and parametric study, the traditional soil-structure interaction direct methods are improved and programmed on: thickness-independent viscous-spring elements for stable static-dynamic boundary transitions; seismic forces separated from the artificial boundary for flexible mesh planning; elevated water simulated with gravity stacking and hydrodynamic action. A nuclear island region encompassing water-cooled RBs and underlying soil cushion layer was investigated as a typical scenario to reveal rules using the proposed high-precision simulation platform. Non-negligible structural risks and correlations between multiple factors were quantitatively elucidated according to simulation findings. A time-lagged increase in the base overturning moment may occur because of water oscillations. As the water level increases to 85 %, the uplift height increases, adversely affecting the in-structure response spectra. Earthquake-induced intense uplift may lead to an increase in hydrodynamic pressure along the inner wall. The research results support the practical assessment of buildings with water cooling facilities located in soft composite sites with high seismic intensities.

A procedure for addressing the soil-abutment interaction problem in the safety assessment of bridges

The paper proposes a methodology for assessing the seismic soil-foundation-abutment response in the spirit of the sub-structure approach. The methodology is suitable for conventional bridge abutments characterized by massive structural components and accommodates for various structural and soil configurations, from both stratigraphic and topographic perspectives. The abutment is assumed to be rigid, which is a generally acceptable hypothesis given the typical geometry of conventional bridge abutments with walls, orthogonal wingwalls, and a concrete deep or strip foundation. The methodology aligns with codes, which foresees a linear behaviour for the abutments and suggest a low behaviour factor to account for dissipative capabilities due to the backfills and the radiation phenomena in the soil. The soil is assumed to perform elastically, but the overall soil nonlinearity induced by seismic wave propagation can be incorporated into the method using a linear equivalent representation of soil properties. The methodology is applied to a real case study in order to demonstrate its effectiveness in addressing the soil-structure interaction problem and to provide practical suggestions for the method implementation, including possible simplifications.