• Coupled systems mechanics
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• v.7 no.4
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• pp.455-483
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• 2018

The study deals with physical modeling of a typical three storeyed building frame supported by a pile group of four piles ($2{\times}2$) embedded in cohesive soil mass using three dimensional finite element analysis. For the purpose of modeling, the elements such as beams, slabs and columns, of the superstructure frame; and that of the pile foundation such as pile and pile cap are descretized using twenty noded isoparametric continuum elements. The interface between the pile and the soil is idealized using sixteen node isoparametric surface element. The soil elements are modeled using eight nodes, nine nodes and twelve node continuum elements. The present study considers the linear elastic behaviour of the elements of superstructure and substructure (i.e., foundation). The soil is assumed to behave non-linear. The parametric study is carried out for studying the effect of soil- structure interaction on response of the frame on the premise of sub-structure approach. The frame is analyzed initially without considering the effect of the foundation (non-interaction analysis) and then, the pile foundation is evaluated independently to obtain the equivalent stiffness; and these values are used in the interaction analysis. The spacing between the piles in a group is varied to evaluate its effect on the interactive behaviour of frame in the context of two embedment depth ratios. The response of the frame included the horizontal displacement at the level of each storey, shear force in beams, axial force in columns along with the bending moments in beams and columns. The effect of the soil- structure interaction is observed to be significant for the configuration of the pile groups and in the context of non-linear behaviour of soil.

• Earthquakes and Structures
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• v.12 no.2
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• pp.251-262
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• 2017

The present research intends to study the effects of the seismic soil-foundation-structure interaction (SFSI) on the dynamic response of various buildings. Two methods including direct and Cone model were studied through 3D finite element method using ABAQUS software. Cone model as an approximate method to consider the SFSI phenomenon was developed and evaluated for both high and low rise buildings. Effect of soil nonlinearity, foundation rigidity and embedment as well as friction coefficient between soil-foundation interfaces during seismic excitation are investigated. Validity and performance of both approaches are evaluated as reference graphs for Cone model and infinite boundary condition, soil nonlinearity and amplification factor for direct method. A series of calculations by DeepSoil for inverse earthquake record modification was conducted. A comparison of the two methods was carried out by root-mean-square-deviation (RMSD) tool for maximum lateral displacement and story shear forces which verifies that Cone model results have good agreement with direct method. It was concluded that Cone method is a convenient, fast and rather accurate method as an approximate way to count for soil media.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.538-547
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• 2005

This paper presents the shaking table testing method, only using building specimen as an experimental part taking into account the dynamic soil-structure interaction based on the substructure method. The Parmelee's soil stiffness is used as an assumed soil model in here. The proposed methodologies are summarized as: (1) Acceleration feedback method is the one that the shaking table is driven by the motion, corresponding to the acceleration at foundation of the total SSI system. This is found by observing the fed-back accelerations of superstructure and using the interaction force based on the acceleration formulation. (2) Velocity feedback method is the one that the shaking table is driven by the motion, corresponding to the velocity at foundation of the total SSI system. This is found by observing the fed-back accelerations of superstructure and using the interaction force based on the velocity formulation. The applicability of the proposed methodologies to the shaking table test is investigated and experimentally verified in this paper.

• Structural Engineering and Mechanics
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• v.88 no.3
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• pp.273-285
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• 2023

This study examines how the interaction between soil and a wind turbine's supporting system affects the optimal design. The supporting system resting on an elastic soil foundation consists of a steel conical tower and a concrete circular raft foundation, and it is subjected to wind loads. The material cost of the supporting system is aimed to be minimized employing various metaheuristic optimization algorithms including teaching-learning based optimization (TLBO). To include the influence of the soil in the optimization process, modified Vlasov and Gazetas elastic soil models are integrated into the optimization algorithms using the application programing interface (API) feature of the structural analysis program providing two-way data flow. As far as the optimal designs are considered, the best minimum cost design is achieved for the TLBO algorithm, and the modified Vlasov model makes the design economical compared with the simple Gazetas and infinitely rigid soil models. Especially, the optimum design dimensions of the raft foundation extremely reduce when the Vlasov realistic soil reactions are included in the optimum analysis. Additionally, as the designated design wind speed is decreased, the beneficial impact of soil interaction on the optimum material cost diminishes.

• Structural Engineering and Mechanics
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• v.49 no.1
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• pp.95-110
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• 2014

The study deals with physical modeling of space frame-pile foundation and soil system using finite element models. The superstructure frame is analyzed using complete three-dimensional finite element method where the component of the frame such as slab, beam and columns are descretized using 20 node isoparametric continuum elements. Initially, the frame is analyzed assuming the fixed column bases. Later the pile foundation is worked out separately wherein the simplified models of finite elements such as beam and plate element are used for pile and pile cap, respectively. The non-linear behaviour of soil mass is incorporated by idealizing the soil as non-linear springs using p-y curve along the lines similar to that by Georgiadis et al. (1992). For analysis of pile foundation, the non-linearity of soil via p-y curve approach is incorporated using the incremental approach. The interaction analysis is conducted for the parametric study. The non-linearity of soil is further incorporated using iterative approach, i.e., secant modulus approach, in the interaction analysis. The effect the various parameters of the pile foundation such as spacing in a group and configuration of the pile group is evaluated on the response of superstructure owing to non-linearity of the soil. The response included the displacement at the top of the frame and bending moment in columns. The non-linearity of soil increases the top displacement in the range of 7.8%-16.7%. However, its effect is found very marginal on the absolute maximum moment in columns. The hogging moment decreases by 0.005% while sagging moment increases by 0.02%.

• Coupled systems mechanics
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• v.3 no.4
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• pp.367-384
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• 2014

The study deals with the physical modeling of a typical single storeyed building frame resting on pile foundation and embedded in cohesive soil mass using the finite element based software SAP-IV. Two groups of piles comprising two and three piles, with series and parallel arrangement thereof, are considered. The slab provided at top and bottom of the frame along with the pile cap is idealized as four noded and two dimensional thin shell elements. The beams and columns of the frame, and piles are modeled using two noded one dimensional beam-column element. The soil is modeled using closely spaced discrete linear springs. A parametric study is carried out to investigate the effect of various parameters of the pile foundation, such as spacing in a group and number of piles in a group, on the response of superstructure. The response considered includes the displacement at the top of the frame and bending moment in columns. The soil-structure interaction effect is found to increase the displacement in the range of 38 -133% and to increase the absolute maximum positive and negative moments in the column in the range of 2-12% and 2-11%. The effect of the soil- structure interaction is observed to be significant for the type of foundation and soil considered in this study. The results obtained are compared further with those of Chore et al. (2010), wherein different idealizations were used for modeling the superstructure frame and sub-structure elements (foundation). While fair agreement is observed in the results in either study, the trend of the results obtained in both studies is also same.

• Structural Engineering and Mechanics
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• v.46 no.5
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• pp.645-672
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• 2013

The differential settlements and rotations among footings cannot be avoided when the frame-footing-soil system is subjected to seismic/dynamic loading. Also, there may be a situation where column(s) of a building are located near adjoining property line causes eccentric loading on foundation system. The strap beams may be provided to control the rotation of the footings within permissible limits caused due to such eccentric loading. In the present work, the seismic interaction analysis of a three-bay three-storey, space frame-footing-strap beam-soil system is carried out to investigate the interaction behavior using finite element software (ANSYS). The RCC structure and their foundation are assumed to behave in linear manner while the supporting soil mass is treated as nonlinear elastic material. The seismic interaction analyses of space frame-isolated footing-soil and space frame-strap footing-soil systems are carried out to evaluate the forces in the columns. The results indicate that the bending moments of very high magnitude are induced at column bases resting on eccentric footing of frame-isolated footing-soil interaction system. However, use of strap beams controls these moments quite effectively. The soil-structure interaction effect causes significant redistribution of column forces compared to non-interaction analysis. The axial forces in the columns are distributed more uniformly when the interaction effects are considered in the analysis.

• Structural Engineering and Mechanics
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• v.19 no.6
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• pp.619-637
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• 2005

The objective of this research was to determine the Vlasov soil parameters for quadratically varying elasticity modulus $E_s$(z) of the compressible soil continuum and discuss the interaction affect between two close plates. Interaction problem carried on for uniformly distributed load carrying plates. Plate region was simulated by Kirchhoff plate theory based (mixed or displacement type) 2D elements and the foundation continuum was simulated by displacement type 2D elements. At the contact region, plate and foundation elements were geometrically coupled with each other. In this study the necessary formulas for the Vlasov parameters were derived when Young's modulus of the soil continuum was varying as a quadratic function of z-coordinate through the depth of the foundation. In the examples, first the elements and the iterative FE algorithm was verified and later the results of quadratic variation of $E_s$(z) were compared with the previous examples in order to discuss the general behavior. As a final example two plates close to each other resting on elastic foundation were handled to see their interaction influences on the Vlasov foundation parameters. Original examples were solved using both mixed and displacement type plate elements in order to confirm the results.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.98-105
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• 2002

The effects of the base-isolation system and elastic soil foundation on the behavior of a liquid storage tank are studied. To evaluate the seismic response of liquid storage tank accurately, the coupled dynamic system considering base isolation and soil interaction problem is formulated in time domain. Results show that the base isolation system reduces effectively the radial displacements, base shears, overturning moments, axial resultant stresses and the hydrodynamic pressure by providing flexibility and energy dissipation capability. Base Isolation may, however, increase the relative liquid sloshing amplitude due to the effect of liquid-structure interaction and cause excessive large relative displacements between structure and foundation. In addition to base-isolator, the dynamic behavior of liquid storage tank is related to the flexibility of base foundation, so the analysis of soil-structure interaction s achieved.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.3-25
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• 2003

In this presentation, soil dynamics for vibrating machine foundation is briefly stated, and the result of a model pile test is presented. Analystical methods used in solving for the stiffness and damping factor for pile-soil system are also treated and the results of the test and the calculated values are compared.