• Title, Summary, Keyword: soil-structure interaction

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Optimal Design of Integrated Control System Considering Soil-Structure Interaction (지반-구조물 상호작용을 고려한 복합제어시스템의 최적설계)

  • Park, Kwan-Soon;Park, Jang-Ho
    • Journal of the Korean Society of Safety
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    • v.27 no.2
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    • pp.57-64
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    • 2012
  • For the vibration control of earthquake-excited buildings, an optimal design method of integrated control system considering soil-structure interaction is studied in this paper. Interaction between soils and the base of the building is simply modeled as lumped parameters and equations of motion are derived. The equations of motion are transformed into the state space equations and the probabilistic excitations such as Kanai-Tajumi power spectral density function is introduced. Then an optimization problem is formulated as finding hybrid or integrated control systems which minimizes the stochastic responses of the building structure for given constraints. In order to investigate the feasibility of the optimization method, an example design and numerical simulations are performed with tenstory building. Finally, numerical results are compared with a conventional design case that soil-structure interaction is not considered.

The effects of foundation size on the seismic performance of buildings considering the soil-foundation-structure interaction

  • Nguyen, Quoc Van;Fatahi, Behzad;Hokmabadi, Aslan S.
    • Structural Engineering and Mechanics
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    • v.58 no.6
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    • pp.1045-1075
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    • 2016
  • Shallow footings are one of the most common types of foundations used to support mid-rise buildings in high risk seismic zones. Recent findings have revealed that the dynamic interaction between the soil, foundation, and the superstructure can influence the seismic response of the building during earthquakes. Accordingly, the properties of a foundation can alter the dynamic characteristics (natural frequency and damping) of the soil-foundation-structure system. In this paper the influence that shallow foundations have on the seismic response of a mid-rise moment resisting building is investigated. For this purpose, a fifteen storey moment resisting frame sitting on shallow footings with different sizes was simulated numerically using ABAQUS software. By adopting a direct calculation method, the numerical model can perform a fully nonlinear time history dynamic analysis to realistically simulate the dynamic behaviour of soil, foundation, and structure under seismic excitations. This three-dimensional numerical model accounts for the nonlinear behaviour of the soil medium and structural elements. Infinite boundary conditions were assigned to the numerical model to simulate free field boundaries, and appropriate contact elements capable of modelling sliding and separation between the foundation and soil elements are also considered. The influence of foundation size on the natural frequency of the system and structural response spectrum was also studied. The numerical results for cases of soil-foundation-structure systems with different sized foundations and fixed base conditions (excluding soil-foundation-structure interaction) in terms of lateral deformations, inter-storey drifts, rocking, and shear force distribution of the structure were then compared. Due to natural period lengthening, there was a significant reduction in the base shears when the size of the foundation was reduced. It was concluded that the size of a shallow foundation influences the dynamic characteristics and the seismic response of the building due to interaction between the soil, foundation, and structure, and therefore design engineer should carefully consider these parameters in order to ensure a safe and cost effective seismic design.

Nonlinear Seismic Response Analysis for Shallow Soft Soil Deposits (낮은 심도의 연약지반에 대한 비선형 지진응답해석)

  • Park, Hong-Gun;Kim, Dong-Kwan;Lee, Kyung-Koo;Kim, Dong-Soo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.5
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    • pp.1-12
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    • 2010
  • This study presents a finite element analysis method that can accurately evaluate the nonlinear behaviour of structures affected by shallow soft subsoils and the soil-structure interaction. A two-dimensional finite element model that consists of a structure and shallow soft subsoil was used. The finite element model was used for a nonlinear time domain analysis of the OpenSees program. A parametric study was performed to investigate the effects of soil shear velocities, earthquake input motions, soft soil depth, and soil-structure interaction. The result of the proposed nonlinear finite element analysis method was compared with the result of an existing frequency domain analysis method, which is frequently used for addressing nonlinear soil behavior. The result showed that the frequency domain analysis, which uses equivalent secant soil stiffness and does not address the soil-structure interaction, significantly overestimated the response of the structures with short dynamic periods. The effect of the soil-structure interaction on the response spectrum did not significantly vary with the foundation dimensions and structure mass.

Seismic Response of Structure on Flexible Foundation (유연한 기초 위에 세워진 구조물의 지진거동)

  • 김용석
    • Journal of the Earthquake Engineering Society of Korea
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    • v.1 no.1
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    • pp.11-17
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    • 1997
  • Seismic analyses of structures were carried out in the past assuming a right base and Ignoring the characteristics of foundations and the properties of the underlying soil. Resent soil-structure interaction studies show that seismic response of structure can be affected significantly by these fators. Typical effects of the soil-structure interaction are the kinematic interaction of a rigid massiess foundation and the inertial interaction between underlying soil and structure. The kinematic interaction effect is particularly important for embedded foundations and can be ignored for surface foundations with vertically propagating waves. In this study, seismic response of structure was investigated with four buildings in Mexico City considering only the inertial interaction effect and using the E-W components of the 1985 Mexico City earthquake records. The study was carried out for surface foundations and pile foundations with linear and nonlinear soil conditions, comparing the results with those of the rigid base.

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Proposed New Evaluation Method of the Site Coefficients Considering the Effects of the Structure-Soil Interaction (구조물-지반 상호작용 영향을 고려한 새로운 지반계수 평가방법에 대한 제안)

  • Kim, Yong-Seok
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.327-336
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    • 2006
  • Site coefficients in IBC and KBC codes have some limits to predict the rational seismic responses of a structure, because they consider only the effect of the soil amplification without the effects of the structure-soil interaction. In this study, upper and lower limits of site coefficients are estimated through the pseudo 3-D elastic seismic response analyses of structures built on linear or nonlinear soil layers considering the structure-soil interaction effects. Soil characteristics of site classes of A, B, and C were assumed to be linear, and those of site classes of D and E were done to be nonlinear and the Ramberg-Osgood model was used to evaluate shear modulus and damping ratio of a soil layer depending on the shear wave velocity of a soil layer. Seismic analyses were performed with 12 weak or moderate earthquake records, scaled the peak acceleration to 0.1g or 0.2g and deconvoluted as earthquake records at the bedrock 30m beneath the outcrop. With the study results of the elastic seismic response analyses of structures, new standard response spectrum and upper and lower limits of the site coefficients of Fa and Fv at the short period range and the period of 1 second are suggested Including the structure-soil interaction effects.

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Analysis of Soil-Structure Interaction of a Long-Span Bridge Considering Incident Angle of Input Ground Motion (입사각을 고려한 장대교량의 지반-구조물 상호작용 해석)

  • Park, Jang-Ho;Shin, Yung-Seok;Choi, Seung-Hwan
    • Journal of the Korean Society of Safety
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    • v.23 no.2
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    • pp.7-13
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    • 2008
  • In a long-span bridge which is constructed on soft soil, it is requested to make a plan considering soil-structure interaction, and soil-structure interaction is partially under consideration at the actual bridge plan. Many researches on dynamic behavior of a bridge affected by soil-structure interacting have been accomplished, but it is difficult to estimate dynamic behavior of a bridge on soft soil accurately because of many uncertainties. This paper presents the results about dynamic response of a long-span suspension bridge in the site composed of soft soil considering incident angle of input ground motion. The effect of soft soil was evaluated by the use o computer program SASSI and a long-span suspension bridge was modeled by finite element program MIDAS. The effect of incident angle of input ground motion was investigated on the dynamic response of a long-span bridge.

Probabilistic capacity spectrum method considering soil-structure interaction effects (지반-구조물 상호작용 효과를 고려한 확률론적 역량스펙트럼법)

  • Nocete, Chari Fe M.;Kim, Doo-Kie;Kim, Dong-Hyawn;Cho, Sung-Gook
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.65-70
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    • 2008
  • The capacity spectrum method (CSM) is a deterministic seismic analysis approach wherein the expected seismic response of a structure is established as the intersection of the demand and capacity curves. Recently, there are a few studies about a probabilistic CSM where uncertainties in design factors such as material properties, loads, and ground motion are being considered. However, researches show that soil-structure interaction also affects the seismic responses of structures. Thus, their uncertainties should also be taken into account. Therefore, this paper presents a probabilistic approach of using the CSM for seismic analysis considering uncertainties in soil properties. For application, a reinforced concrete bridge column structure is employed as a test model. Considering the randomness of the various design parameters, the structure's probability of failure is obtained. Monte Carlo importance sampling is used as the tool to assess the structure's reliability when subjected to earthquakes. In this study, probabilistic CSM with and without consideration of soil uncertainties are compared and analyzed. Results show that the analysis considering soil structure interaction yields to a greater probability of failure, and thus can lead to a more conservative structural design.

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Soil-structure interaction analysis of beams resting on multilayered geosynthetic-reinforced soil

  • Deb, Kousik
    • Interaction and multiscale mechanics
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    • v.5 no.4
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    • pp.369-383
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    • 2012
  • In this paper, soil-structure interaction analysis has been presented for beams resting on multilayered geosynthetic-reinforced granular fill-soft soil system. The soft soil and geosynthetic reinforcements are idealized as nonlinear springs and elastic membranes, respectively. The governing differential equations are solved by finite difference technique and the results are presented in non-dimensional form. It is observed from the study that use of geosynthetic reinforcement is not very effective for maximum settlement reduction in case of very rigid beam. Similarly the reinforcements are not effective for shear force reduction if the granular fill has very high shear modulus value. However, multilayered reinforced system is very effective for bending moment and differential settlement reduction.

Nonlinear Soil-Structure Interaction Analysis of a Seismically Isolated Nuclear Power Plant Structure using the Boundary Reaction Method (경계반력법을 이용한 지진격리 원전구조물의 비선형 지반-구조물 상호작용 해석)

  • Lee, Eun-Haeng;Kim, Jae-Min;Lee, Sang-Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.19 no.1
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    • pp.37-43
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    • 2015
  • This paper presents a detailed procedure for a nonlinear soil-structure interaction of a seismically isolated NPP(Nuclear Power Plant) structure using the boundary reaction method (BRM). The BRM offers a two-step method as follows: (1) the calculation of boundary reaction forces in the frequency domain on an interface of linear and nonlinear regions, (2) solving the wave radiation problem subjected to the boundary reaction forces in the time domain. For the purpose of calculating the boundary reaction forces at the base of the isolator, the KIESSI-3D program is employed in this study to solve soil-foundation interaction problem subjected to vertically incident seismic waves. Wave radiation analysis is also employed, in which the nonlinear structure and the linear soil region are modeled by finite elements and energy absorbing elements on the outer model boundary using a general purpose nonlinear FE program. In this study, the MIDAS/Civil program is employed for modeling the wave radiation problem. In order to absorb the outgoing elastic waves to the unbounded soil region, spring and viscous-damper elements are used at the outer FE boundary. The BRM technique utilizing KIESSI-3D and MIDAS/Civil programs is verified using a linear soil-structure analysis problem. Finally the method is applied to nonlinear seismic analysis of a base-isolated NPP structure. The results show that BRM can effectively be applied to nonlinear soil-structure interaction problems.

Overview on Standards for Soil-Structure Interaction Analysis used in Design of Infrastructure (일반 시설물의 지반-구조물 상호작용 해석 기준에 대한 고찰)

  • Kim, Hyun-Uk;Ha, Jeong-Gon;Kim, Dong-Soo;Joo, Kwang-Ho
    • Journal of the Earthquake Engineering Society of Korea
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    • v.21 no.5
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    • pp.227-236
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    • 2017
  • This study reviews concepts, theories and formulas included in standards on soil-structure interaction and also shows practical example of application for engineers. Real structures are 3 dimensional and multi degree of freedom but they are often idealized to single degree of freedom for convenience. In this study, detailed procedures to calculate soil spring constants and damping coefficients and method to model soil-structure system are explained. Additionally, case studies to judge fixed base condition and evaluation of applicability of simple analysis method based on response spectra are performed.