• Steel and Composite Structures
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• 제13권2호
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• pp.109-122
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• 2012

An efficient and accurate algorithm is proposed to evaluate the reliability of cable-stayed bridges accounting for soil-pile interaction. The proposed algorithm integrates the finite-element method and the response surface method. The finite-element method is used to model the cable-stayed bridge including soil-pile interaction. The reliability index is evaluated based on the response surface method. Uncertainties in the superstructure, the substructure and load parameters are incorporated in the proposed algorithm. A long span steel cable-stayed bridge with a main span length of 1088 m built in China is considered as an illustrative example. The reliability of the bridge is evaluated for the strength and serviceability performance functions. Results of the study show that when strength limit states for both girder and tower are considered, soil-pile interaction has significant effects on the reliability of steel cable-stayed bridges. Further, a detailed sensitivity study shows that the modulus of subgrade reaction is the most important soil-pile interaction-related parameter influencing the reliability of steel cable-stayed bridges.

• 한국지반공학회논문집
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• 제19권4호
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• pp.211-221
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• 2003

지중구조물의 내진해석에 자주 이용되는 방법으로 응답변위법이 있다. 응답변위법은 정적인 해석방법으로, 이 방법의 핵심은 지진시 지중구조물 측벽에 작용하는 지반변위를 산정하는 것이다. 이때 해석대상부지의 고유주기에 해당하는 기반면의 속도 응답스펙트럼 값을 결정하는 일이 매우 중요하다. 본 연구에서는 국내 설계지반운동기준에 적합한 기반면의 속도 응답스펙트럼 산정과 지반응답해석 없이 응답변위를 신뢰성있게 산정하는 간편법에 대한 연구를 수행하였다. 해석결과 국내 내진설계 기준의 S$_A$ 지반의 지표면 가속도 응답스펙트럼을 적분하여 속도 응답스펙트럼으로 환산하는 방법과 지반을 두 개의 층으로 구분하여 지진시 지반의 응답변위를 산정하는 방법을 현업 설계에 적용할 경우 경제적으로 큰 잇점이 있을 것으로 판단된다.

• 한국농공학회논문집
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• 제48권6호
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• pp.45-56
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• 2006

The finite element method is a practical tool to compute the response of the irregularly layered soil deposit to the base-rock motions. The method is useful not only in estimating the interaction between the structure and the surrounding soil as a whole and the local behavior of the contacting area in detail, but also in predicting the resulting behavior of the superstructure affected by such soil-structure interactions. However, the computation of finite element analysis is marched in the time domain (TD), while the site response analysis has been carried out mostly in the frequency domain (FD) with equivalent linear analysis. This study is intended to compare the results of the TD and FD analysis with focus on the peak response accelerations and the predominant frequencies, and thus to evaluate the applicability and the validity of the finite element analysis in the site response analysis. The comparison shows that one can obtain the results very close to that of FD analysis, from the finite element analysis by including sufficiently large width of foundation in the model and further by applying partial mode superposition. The finite element analysis turned out to be well agreeing with FD analysis in their computed results of the peak acceleration and the acceleration response spectra, especially at the surface layer.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.433-438
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• 2001

The response spectrum has been widely used to differentiate the significant characteristics of earthquake ground motion and to evaluate the response of structures under ground shaking. Current design response spectrum is based on Seed, Ugas, and Lysmer's study. (1976) In this study, earthquake ground motion data sets adopted by Seed, Miranda, and Riddell is analyzed regards to soil types. And how earthquake data sets effected the design response spectrum is evaluated using acceleration-displacement response spectrum.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.617-624
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• 2006

Site response analysis is widely used in estimating local seismic site effects. The soil behavior in the analysis is assumed to be Independent of the rate of the seismic loading laboratory results, however, indicate that cohesive soil behavior is greatly influenced by the rate of loading. A new equivalent linear analysis method is developed that accounts for the rate-dependence of soil behavior and used to perform a series of one dimensional site response analyses. Results indicate that while rate-dependent shear modulus has limited influence on computed site response, rate-dependent soil damping greatly filters out high frequency components of the ground motion and thus results in lower response.

• Structural Engineering and Mechanics
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• 제24권3호
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• pp.275-290
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• 2006

In this paper, the performance of a tuned liquid damper (TLD) in suppressing the seismic response of buildings is investigated with shake table testing of a four-story steel frame model that rests on pile foundation. The model tests were performed in three phases with the steel frame structure alone, the soil and pile foundation system, and the soil-foundation-structure system, respectively. The test results from different phases were compared to study the effect of soil-structure interaction on the efficiency of a TLD in reducing the peak response of the structure. The influence of a TLD on the dynamic response of the pile foundation was investigated as well. Three types of earthquake excitations were considered with different frequency characteristics. Test results indicated that TLD can suppress the peak response of the structure up to 20% regardless of the presence of soils. TLD is also effective in reducing the dynamic responses of pile foundation.

• Steel and Composite Structures
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• 제42권2호
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• pp.209-219
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• 2022

Offshore platforms in seismically active areas must be designed to survive in the face of intense earthquakes without a global structural collapse. This paper scrutinizes the seismic performance of a newly designed and established jacket type offshore platform situated in the entrance of the Gulf of Suez region based on the API-RP2A normalized response spectra during seismic events. A nonlinear finite element model of a typical jacket type offshore platform is constructed taking into consideration the effect of structure-soil-interaction. Soil properties at the site were manipulated to generate the pile lateral soil properties in the form of load deflection curves, based on API-RP2A recommendations. Dynamic characteristics of the offshore platform, the response function, output power spectral density and transfer functions for different elements of the platform are discussed. The joints deflection and acceleration responses demands are presented. It is generally concluded that consideration of the interaction between structure, piles and soil leads to higher deflections and less stresses in platform elements due to soil elasticity, nonlinearity, and damping and leads to a more realistic platform design. The earthquake-based analysis for offshore platform structure is essential for the safe design and operation of offshore platforms.

• 한국지진공학회논문집
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• 제14권5호
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• pp.1-12
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• 2010

본 연구에서는 얕은 연약지반에서 구조물-지반 상호작용의 영향을 받는 구조물의 비탄성거동을 정확히 나타낼 수 있는 유한요소해석 방법을 연구하였다. 이를 위하여, 국내의 지반특성을 반영한 얕은 연약지반과 단자유도 구조물로 2차원 유한요소모델을 구성하고, 다양한 지진파와 지반에 대해 OpenSees 해석프로그램을 이용한 비선형 시간이력해석을 수행하였다. 연약지반의 비선형거동을 반영하기 위하여 일반적으로 흔히 사용되는 등가선형 주파수영역 해석 결과와 비선형 시간이력 유한요소해석 결과의 차이를 검토하였다. 그 비교결과는 등가선형강성을 사용하고 지반-구조물 상호작용을 고려하지 않는 주파수영역해석은 단주기영역의 구조물의 응답스펙트럼을 과대평가할 수 있음을 보여주었다. 응답스펙트럼에 대한 지반-구조물 상호작용의 영향은 기초크기와 구조물의 질량의 변화와 큰 관계 없이 일정하게 나타났다.

• Structural Engineering and Mechanics
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• 제41권3호
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• pp.395-406
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• 2012

Basic problem of pile foundation is three dimensional in nature. Three dimensional finite element formulation is employed for the analysis of pile groups. Pile, pile-cap and soil are modeled using 20 node element, whereas interface between pile or pile cap and soil is modeled using 16 node surface element. A parametric study is carried out to consider the effect of pile spacing, number of piles, arrangement of pile and soil modulus on the response of pile group. Results indicate that the response of pile group is dependent on these parameters.

• Earthquakes and Structures
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• 제7권2호
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• pp.233-250
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• 2014

In this paper, a three dimensional soil-structure interaction (SSI) is numerically simulated using finite element method in order to analyse the foundation moments in annular raft of tall slender chimney structures incorporating the effect of openings in the structure and the effect of soil flexibility, when the structure-soil system is subjected to El Centro (1940) ground motion in time domain. The transient dynamic analysis is carried out using LS-DYNA software. The linear ground response analysis program ProShake has been adopted for obtaining the ground level excitation for different soil conditions, given the rock level excitation. The radial and tangential bending moments of annular raft foundation obtained from this SSI analysis have been compared with those obtained from conventional method according to the Indian standard code of practice, IS 11089:1984. It is observed that tangential and radial moments increase with the increase in flexibility of soil. The analysis results show that the natural frequency of chimney decreases with increase in supporting soil flexibility. Structural responses increase when the openings in the structure are also considered. The purpose of this paper is to propose the need for an accurate evaluation of the soilstructure interaction forces which govern the structural response.