• Coupled systems mechanics
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• v.6 no.3
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• pp.229-249
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• 2017

A new technique to mitigate irregular buildings with soil structure interaction (SSI) effect subjected to critical seismic waves is presented. The L-shape in plan irregular building for various reasons was selected, subjected to seismic a load which is a big problem for structural design especially without separation gap. The L-shape in plan building with different dimensions was chosen to study, with different rectangularity ratios and various soil kinds, to show the effect of the irregular building on the seismic response. A 3D building subjected to critical earthquake was analyzed by structural analysis program (SAP2000) fixed and with SSI (three types of soils were analyzed, soft, medium and hard soils) to find their effect on top displacement, base shear, and base torsion. The straining actions were appointed and the treatment of the effect of irregular shape under critical earthquake was made by using tuned mass damper (TMD) with different configurations with SSI and without. The study improve the success of using TMDs to mitigate the effect of critical earthquake on irregular building for both cases of study as fixed base and raft foundation (SSI) with different TMDs parameters and configurations. Torsion occurs when the L-shape in plan building subjected to earthquake which may be caused harmful damage. TMDs parameters which give the most effective efficiency in the earthquake duration must be defined, that will mitigate these effects. The parameters of TMDs were studied with structure for different rectangularity ratios and soil types, with different TMD configurations. Nonlinear time history analysis is carried out by SAP2000 with El Centro earthquake wave. The numerical results of the parametric study help in understanding the seismic behavior of L-shape in plan building with TMDs mitigation system.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.23-31
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• 2001

지반 위에 세워진 구조물의 지진응답해석시 지반-구조물 상호작용 영향은 지반으 선형특성을 고려하여 간주되었는데 최근 연구결과에 의하면 구조물 지진해석에서 연약지반의 비선형 특성이 중요한 요소로서 인식되었다. 하지만 지반-구조물계의 복잡한 비선형 특성 때문에 내진설계 기준에서 비선형 지반특성을 고려하기에는 아직도 어려움이 많다. 이 논문에서는 UBC 지반종류 $S_{D}$ 지반 위에 놓인 중규모의 얕은 온통기초와 묻힌 온통기초위에 세워진 건물에 대한 단자유도계 선형 지진해석을 연약지반의 비선형성을 고려하여 최대가속도가 0.17g 과 0.36g 인 Taft E-W 및 El Centro N-S 지진기록을 사용하여 수행하였다. 비선형 지진해석을 결과를 선형해석 결과와 비교하였을 때, 비선형 응답스펙트럼의 최대가속도가 지반의 비선형성 때문에 상당히 줄어드는 것으로 나타나 지반의 비선형성을 고려한 더효율적인 내진설계의 가능성을 보여준다.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.3
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• pp.55-65
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• 2000

구조물 지진해석을 위한 구조물 -지반 상호작용 해석에서도 비선형 지반 특성을 고려한 비선형해석이 요구되고 있어 구조물 비선형 지진 해석을 위해 기초 지반에 대한 수평방향 비선형 해석을 수행하였다. 기초지반은 UBC 분류에서 규정한 보통지반인 Sn 지반과 연약지반인 SE 지반을 고려하였고, 지반의 비선형 특성은 Ramberg-Osgood 모델을 이용하였다. 비선형 지반이 기초지반 수평 및 회전 동적 강성 및 감쇠비에 미치는 영향을 조사하기 위하여 얕은 기초와 묻힌기초에 대해 기초 크기, 지반깊이 및 말뚝유무에 따른 동적 강성 및 감쇠비 변화를 조사하였는데, 지반의 비선형 특성이 기초지반의 선형 수평 및 회전 강성과 감쇠비를 크게 감소 또는 증가시키는 것으로 나타났으며, 기초크기, 지반깊이 및 말뚝유무의 영향도 큰 것으로 나타나 구조물 지진해석시 기초크기, 지반깊이 및 말뚝유무와 함께 지반의 비선형성도 고려하는 것이 필요한 것으로 판단되었다.

• Earthquakes and Structures
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• v.11 no.1
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• pp.141-163
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• 2016

Fiber models have been developed and applied to various structural elements such as shear walls, beams and columns. Only scarcely have fiber models been applied to circular foundation systems such as cast in drilled holes shafts (CIDH). In pile foundations with constraint head boundary conditions, shear deformations can easily contribute to the lateral pile response. However, soil structure interaction formulations such as the p-y method, commonly used for lateral pile design, do not include structural shear deformations in its traditional derivation method. A fiber model that couples shear and axial-bending behavior, originally developed for wall elements was modified and validated on circular cross sections (columns) before being applied to a 0.61 m diameter reinforced concrete (RC) pile with fixed head boundary conditions. The analytical response was compared to measured test results of a fixed head test pile to investigate the possible impact of pile shear deformations on the displacement, shear, and moment profiles of the pile. Results showed that shear displacements and forces are not negligible and suggest that nonlinear shear deformations for RC piles should be considered for fixed-head or similar conditions. Appropriate sensor layout is recommended to capture shear deformation when deriving p-y curves from field measurements.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.241-248
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• 1997

The super-structure in a soil-structure interaction analysis is commonly idealized as lumped parameter system. In this study, the complex shear wall structure is modeled using three different kinds of modeling techniques : 1) full FEM comparatively as an exact solution, 2)equivalent shear spring model assuming mainly shear deformations of the wall, 3) equivalent beam-stick model made by independent static analysis. Dynamic characteristics due to three different modeling methods are compared and investigated before performing structural response analysis. The beam-stick model in comparison to shear spring model gives closer dynamic responses when compared with the full FEM, even though it requires additional unit load static analyses.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.107-114
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• 1997

A dynamic fluid-structure-soil interaction analysis method is developed to investigate the effects of rocking motion on the seismic response of the 3-D flexible rectangular liquid storage tanks founded on the deformable ground. The governing equation of 3-D rectangular tanks subjected to the translational and rocking motions is obtained by Rayleigh-Ritz method. The dynamic stiffness matrix of the rigid surface foundation resting on the surface of a stratum are calculated by hyperelement method. The seismic responses of a 3-D flexible tank model founded on the deformable ground is calculated by combining the governing equation of the structural motion with the dynamic stiffness matrix of the rigid surface foundation.

• Wind and Structures
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• v.21 no.6
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• pp.597-607
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• 2015

With an increasing demand of a renewable energy, new offshore wind turbine farms are being planned in some parts of the world. Foundation installation asks a significant cost of the total budget of offshore wind turbine (OWT) projects. Hence, a cost reduction from foundation parts is a key element when a cost-efficient designing of OWT budget. Mono-piles have been largely used, accounting about 78% of existing OWT foundations, because they are considered as a most economical alternative with a relatively shallow-water, less than 30 m of seawater depth. OWT design standards such as IEC, GL, DNV, API, and Eurocode are being developed in a form of reliability based limit state design method. In this paper, reliability analysis using the response surface method (RSM) and numerical simulation technique for an OWT mono-pile foundation were performed to investigate the sensitivities of mono-pile design parameters, and to find practical implications of RSM reliability analysis.

• Earthquakes and Structures
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• v.16 no.1
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• pp.11-28
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• 2019

This article investigates the response of Integral Abutment Bridges (IAB) when subjected to a sequence of seasonal thermal loading of the deck followed by ground seismic shaking in the longitudinal direction. Particular emphasis is placed on the effect of pre-seismic thermal Soil-Structure Interaction (SSI) on the seismic performance of the IAB, as well as on the ability of various backfills configurations, to minimize the unfavorable SSI effects. A series of two-dimensional numerical analyses were performed for this purpose, on a complete backfill-integral bridge-foundation soil system, subjected to seasonal cyclic thermal loading of the deck, followed by ground seismic shaking, employing ABAQUS. Various backfill configurations were investigated, including conventional dense cohesionless backfills, mechanically stabilized backfills and backfills isolated by means of compressive inclusions. The responses of the investigated configurations, in terms of backfill deformations and earth pressures, and bridge resultants and displacements, were compared with each other, as well as with relevant predictions from analyses, where the pre-seismic thermal SSI effects were neglected. The effects of pre-seismic thermal SSI on the seismic response of the coupled IAB-soil system were more evident in cases of conventional backfills, while they were almost negligible in case of IAB with mechanically stabilized backfills and isolated abutments. Along these lines, reasonable assumptions should be made in the seismic analysis of IAB with conventional sand backfills, to account for pre-seismic thermal SSI effects. On the contrary, the analysis of the SSI effects, caused by thermal and seismic loading, can be disaggregated in cases of IAB with isolated backfills.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.129-137
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• 2020

In performing the structural analysis, the foundation is considered to be a fixed end as a plastic hinge model. In this study, the displacements of the foundation, pier, and shoe were compared when the foundation modeled as a fixed end, a shallow foundation constructed on bedrock of 2m depth, and a pile foundation constructed in the 10m to 20m depth of bedrock. The shear force was also compared, and the probability of damage was calculated and compared for the critical condition. When calculated as a fixed end, the displacement of the foundation converged to 0mm, but the shallow foundation built on the bedrock with a depth of 2m caused relatively displacement, and the pile foundation constructed to contact the bedrock with a depth of 18m caused a larger displacement. In addition, it was analyzed that the displacement of the foundation, which is the lower structure, affects the displacement of the super structure, but the difference in shear force applied to the foundation was insignificant in the three cases. There was no difference between the shallow foundation and the pile foundation in the influence on the displacement of the top of the pier, but there was a big difference from the analysis assuming as a fixed end.

• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.29-40
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• 2013

Seismic response of single degree of freedom system supported by shallow foundation was analyzed by using nonlinear explicit finite difference element code. Numerical analysis results were verified with dynamic centrifuge test results of the same soil profile and structural dimensions with the numerical analysis model at a centrifugal acceleration of 20 g. Differences between the analysis and the test results induced by the boundary conditions of control points can be reduced by adding additional local damping to the natural born cyclic hysteretic damping of the soil strata. The analysis results show good agreement with the test results in terms of both time histories and response spectra. Thus, it can be concluded that the nonlinear explicit finite difference element code will be a useful technique for estimating seismic residual displacement, earthpressure etc. which are difficult to measure during laboratory tests and real earthquake.