Showing papers on "Soil structure interaction published in 2021"

Numerical simulation of the seismic response and soil–structure interaction for a monitored masonry school building damaged by the 2016 Central Italy earthquake

Abstract: Despite significant research advances on the seismic response analysis, there is still an urgent need for validation of numerical simulation methods for prediction of earthquake response and damage. In this respect, seismic monitoring networks and proper modelling can further support validation studies, allowing more realistic simulations of what earthquakes can produce. This paper discusses the seismic response of the “Pietro Capuzi” school in Visso, a village located in the Marche region (Italy) that was severely damaged by the 2016–2017 Central Italy earthquake sequence. The school was a two-story masonry structure founded on simple enlargements of its load-bearing walls, partially embedded in the alluvial loose soils of the Nera river. The structure was monitored as a strategic building by the Italian Seismic Observatory of Structures (OSS), which provided acceleration records under both ambient noise and the three mainshocks of the seismic sequence. The evolution of the damage pattern following each one of the three mainshocks was provided by on-site survey integrated by OSS data. Data on the dynamic soil properties was available from the seismic microzonation study of the Visso village and proved useful in the development of a reliable geotechnical model of the subsoil. The equivalent frame (EF) approach was adopted to simulate the nonlinear response of the school building through both fixed-base and compliant-base models, to assess the likely influence of soil–structure interaction on the building performance. The ambient noise records allowed for an accurate calibration of the soil–structure model. The seismic response of the masonry building to the whole sequence of the three mainshocks was then simulated by nonlinear time history analyses by using the horizontal accelerations recorded at the underground floor as input motions. Numerical results are validated against the evidence on structural response in terms of both incremental damage and global shear force–displacement relationships. The comparisons are satisfactory, corroborating the reliability of the compliant-base approach as applied to the EF model and its computational efficiency to simulate the soil–foundation–structure interaction in the case of masonry buildings.

Application of discrete wavelet transform in seismic nonlinear analysis of soil–structure interaction problems:

Abstract: Simulation of soil–structure interaction (SSI) effects is a time-consuming and costly process. However, ignoring the influence of SSI on structural response may lead to inaccurate results, especial...

Effects of dynamic soil-structure interaction on seismic behaviour of high-rise buildings

Abstract: It is conventional to assume that the role of the soil-structure interaction (SSI) is beneficial to the buildings under seismic loading. However, lessons learned from recent earthquakes revealed that this assumption could be misleading, and SSI may have different effects on the seismic response of different structural systems. In this study, an enhanced soil-structure numerical model is developed and verified using ABAQUS software to assess the impact of SSI on high-rise frame-core tube structures. The seismic responses of 20, 30, and 40-storey buildings constructed on soil class Ee (according to Australian Standards) under four earthquake acceleration records have been studied. The results in terms of maximum lateral deflections, foundation rocking, inter-storey drifts and storey shear forces for the rigid base and flexible base frame-core tube structures have been discussed and compared. Generally, SSI has a remarkable impact on the seismic behaviour of high-rise frame-core tube structures since it can increase the lateral deflections and inter-storey drifts and decrease storey shear forces of structures. However, It is worth noting that the seismic responses of soil-structure systems under near and far field earthquakes are considerably different.

Seismic Interaction of Adjacent Structures on Liquefiable Soils: Insight from Centrifuge and Numerical Modeling

Abstract: In urban environments, structures are often built in close proximity to each other. Seismic coupling and structure-soil-structure interaction (SSSI) are known to affect system accelerations...

Correlation between Ground Motion Parameters and Displacement Demands of Mid-Rise RC Buildings on Soft Soils Considering Soil-Structure-Interaction

Abstract: This paper investigates the correlation between ground motion parameters and displacement demands of mid-rise RC frame buildings on soft soils considering the soil-structure interaction. The mid-rise RC buildings are represented by using 5, 8, 10, 13, and 15-storey frame building models with no structural irregularity. A total of 105 3D nonlinear time history analyses were carried out for 21 acceleration records and 5 different building models. The roof drift ratio (RDR) obtained as inelastic displacement demands at roof level normalized by the building height is used for demand measure, while 20 ground motion parameters were used as intensity measure. The outcomes show velocity related parameters such as Housner Intensity (HI), Root Mean Square of Velocity (Vrms), Velocity Spectrum Intensity (VSI) and Peak Ground Velocity (PGV), which reflect inelastic displacement demands of mid-rise buildings as a damage indicator on soft soil deposit reasonably well. HI is the leading parameter with the strongest correlation. However, acceleration and displacement related parameters exhibit poor correlation. This study proposed new combined multiple ground motion parameter equations to reflect the damage potential better than a single ground motion parameter. The use of combined multiple parameters can be effective in determining seismic damages by improving the scatter by at least 24% compared to the use of a single parameter.

Centrifuge and numerical modelling of earthquake-induced soil liquefaction under free-field conditions and by considering soil–structure interaction

Abstract: Modelling earthquake-induced soil liquefaction and assessing its consequences to overlying buildings are still delicate and challenging tasks in geotechnical earthquake engineering. Having been carried out within the European H2020 LIQUEFACT project, this paper focuses on the application of both physical and numerical modelling techniques. We present the complete passage starting from the preparation of the physical models to ending with the comparison of recorded (experimental) and simulated (numerical) results. We discuss in detailed manner the dynamic response of two systems with and without the presence of a structure lying at the top of a uniform, medium-dense, saturated Ticino sand, whose main properties (physical, mechanical, hydraulic, and state) are well known. Through a set of numerical analyses carried out under homogeneous conditions, we provide in this paper insights to throw light into the effect of structure on the system response. Salient conclusion of this work suggests that the presence of structure changes the kinematic response of the system through beneficial effect in terms of increased vertical effective stress and detrimental effect in terms of concentrated strain field present nearby the foundations. Unfortunate combination of those beneficial and detrimental effects results in stronger response in terms of acceleration and larger settlements with the presence of structure with respect to the free-field counterpart.

Finite Element Modeling of Soil Structure Interaction System with Interface: A Review

Abstract: Non-linear analysis of soil structure interaction problem is still an active field of research due to development of useful interface element between the soil–soil and soil–structure. In this paper a focused review on coupled finite element modeling of soil structure interaction (SSI) system with soil non-linearity and interface element modeling is discussed. The non-linearity in soil is reviewed with various available constitutive models, whereas the Interface modeling is reviewed with zero thickness and thin layer elements, which is proposed by many researchers from 1970 to till date with special emphasis on behavior of superstructure. Further the paper discusses on the occurrence of ill conditioning due to significance of interface thickness and selection of normal and tangential stiffness during interface modeling. In addition to above, some special interface element (different degree of freedom on top and bottom face of element) in non-linear SSI is also reviewed. Therefore the attention is on advantages and disadvantages of the discussed methods according to their applicability, accuracy and caliber to idealize the superstructure and soil.

Effects of soil–structure interaction on seismic performance of a low-rise R/C moment frame considering material uncertainties

Abstract: This study investigated the effects of soil–structure interaction (SSI) on the performance of low-rise reinforced concrete (R/C) structures subjected to earthquakes. The uncertainty of material properties, such as steel yield and concrete compressive strengths , was addressed using the Monte Carlo simulation with Latin hypercube sampling . A planar R/C moment frame of three bays and three stories was subjected to 20 selected ground motions for this purpose. In the flexible-base models, the soil was modeled with springs and dashpots, and the mass and moment of inertia of the footing were lumped at the bottom of the column. In contrast, for the fixed-base model, the bottoms of the columns were fixed in all translational and rotational directions. A parametric study was conducted for the shear wave velocity of soil, varying from 1000 to 50 m/s. The responses of the flexible-base and fixed-base models were compared in terms of the ductility, maximum interstory drift , and maximum total drift (ratio of top displacement to building height) for three performance levels in ASCE 41-17: intermediate occupancy (IO), life safety (LS), and collapse prevention (CP). The pushover analysis results indicate that a higher shear wave velocity leads to a higher ductility capacity. The uncertainty of the material properties produces an extensive range of ductility factors. The seismic drift responses of the flexible-base models are larger than those of the fixed-base model, particularly in the range of shear wave velocities less than 180 m/s (i.e., soft soil). From the failure probability analyses, the threshold shear wave velocity below which the effects of SSI should be considered is approximately 180 m/s for IO and 100 m/s for both LS and CP.

Comparing the performance of substructure and direct methods to estimate the effect of SSI on seismic response of mid-rise structures

Abstract: The effects of soil–structure interaction on seismic responses of structures have always been a challenging topic for earthquake and structural engineers. Over the years, different ways have been i...

Modeling Nonlinear-Inelastic Seismic Response of Tall Buildings with Soil–Structure Interaction

Abstract: Soil-structure interaction (SSI) effects are of interest for the seismic analysis and the design of tall buildings on shallow foundations, particularly when both the structure and soil unde...

Effect of Soil–Structure Interaction on Seismic Behavior of Mid- and Low-Rise Buildings

Abstract: This study investigates the effect of soil–structure interaction (SSI) on seismic behavior of mid- and low-rise residential buildings considering linear and nonlinear behavior of structura...

Seismic behaviour of structures adjacent to slope by considering SSI effects in cemented soil mediums

Abstract: Previous studies on seismic behaviour of slope topography have shown that seismic response of ground surface adjacent to slope is intensively influenced by topography shape and geotechnical site co...

Fragility curves of non-ductile RC frame buildings on saturated soils including liquefaction effects and soil–structure interaction

Abstract: Liquefaction constitutes the most common source of seismic damage to buildings resting on saturated soils. Soil-structure interaction (SSI) may also significantly affect the seismic response of structures, modifying their dynamic characteristics and the seismic response at the foundation level. Although progress has been made on the investigation of the influence of soil liquefaction and SSI on the structural response, studies combining both phenomena are very limited. To bridge this gap, we investigate the integrated influence of both liquefaction and SSI on the seismic response and vulnerability of low-code reinforced concrete (RC) moment resisting frame buildings. A two-storey non-ductile RC frame building is adopted as reference. The following numerical models are developed: (1) a fixed-base structure subjected to free-field (FF) motion neglecting liquefaction (and SSI); (2) a fixed-base structure subjected to FF motion allowing liquefaction; (3) a flexible-base structure (i.e. including SSI) resting on soil subjected to outcrop bedrock motion neglecting liquefaction; (4) a flexible-base structure resting on soil subjected to outcrop bedrock motion allowing liquefaction. Conducting nonlinear incremental dynamic analysis for the above-described configurations, we derive seismic fragility curves considering (or not) SSI and/or liquefaction effects for different damage limit states through statistical correlation of the calculated engineering demand parameter with appropriate intensity measures. We also generate vulnerability curves to quantify the expected structural losses. Results show the substantive role of liquefaction and SSI in altering the seismic fragility and vulnerability of non-ductile low-rise RC frame buildings.

Nonlinear Seismic Performance of Nuclear Structure with Soil–Structure Interaction

Abstract: In the present study, the emphasis is made on the seismic performance of nuclear containment constructed on layered medium to dense silty sand soil considering the nonlinearity of the containment structure using the concrete damage plasticity (CDP) model and Drucker–Prager plastic model for soil. The finite element model is prepared using the ABAQUS. From the static pushover analysis, it is noticed that yielding force is reduced up to 8.37% and 2.37% in the case of with and without embedment, respectively, as compared to a fixed base. Furthermore, incremental dynamic analysis is performed for the motion range of 0.1 g to 0.6 g, corresponding to the fundamental frequency. For the dynamic analysis, Kelvin element is used at boundaries to incorporate the truncated soil mass. The results are shown in the form of base shear, base moment and displacement ductility, drift ratio, normalized peak settlement, and normalized peak foundation sliding. Moment demand is reduced up to 25.89% and 51.31% in the case of with and without embedment, respectively, as compared to a fixed base. Similarly, base shear demand is increased up to 21.85% in the case of with embedment. It may reduce up to 29.08% in the case of without embedment of foundation as compared to a fixed base. Drift demand of nuclear power plant (NPP) structure is increased up to 14.47% and 38.16% in the case of with and without embedment of foundation, respectively, as compared to a fixed base. In contrast, displacement ductility demand reduced up to 47.95% and 57.52% in the case of with and without embedment of foundation, respectively. Settlement demand is increased linearly in the case of with embedment with respect to ground motion intensity; however, it increases sharply for ground motion intensity > 0.3 g in the case of without embedment. The sliding demand of foundation increase with a low and fixed amount of sliding is examined in the condition of with embedment case; however, it rises steeply in the case of without embedment case, indicating that without considering the embedment effect may increase the design requirement and therefore lead to uneconomical designing. The effect of the CDP model shows the need to consider the nonlinearity of structure along with the nonlinearity of soil.