• Journal of the Korean Geotechnical Society
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• v.31 no.4
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• pp.31-43
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• 2015

A numerical analysis on the effect of increasing tensile stiffness of the geosynthetics on the soil displacement and pile efficiency was conducted. Parametric studies by changing the stiffness of soft soil, internal friction and dilatancy angles of the embankment material, and flexual stiffness of the composite layer including the geosynthetics were carried out. In general, increasing stiffness of the geosynthetics improves the pile efficiency, whereas the amount of its improvement depends on the condition of parameters. In case of the sufficiently low stiffness of the soft soil or high flexual stiffness of the composite layer including the geosynthetics, a noticeable increase in the pile efficiency can be observed. When the stiffness of the soft soil is very low, the increase in the stiffness of the geosynthetics can significantly reduce the vertical displacement in the piled embankment. When the flexual stiffness of the composite layer is sufficiently high, increasing stiffness of the geosynthetics can greatly improve the pile efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.271-278
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• 2010

Semi rigid pavement is a pavement type using advantages of both flexibility of asphalt pavement and rigidity of concrete pavement by infiltrating cement paste into voids of open graded asphalt mixtures. The semi rigid pavement has better smoothness and smaller driving vibration or noise comparing to the concrete pavement, and has smaller permanent deformation and has temperature falling effect comparing to the asphalt pavement. The temperature falling effect were investigated at a semi rigid overlay pavement test section, and the temperature falling and water retaining effects were verified by measuring the temperature and weight of specimens at a housetop. Horizontal and vertical stresses and strains were compared by structural analysis of the semi rigid pavement and asphalt pavement using the Abaquser o, a commercial 3D finite element analysis program. The results were verified by Bisar 3.0, a multi-layered elastic analysis program. Performance of the semi rigid pavement and asphalt pavement were compared by predicting fatigue cracking based on the structural analysis results.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.261-269
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• 2015

To overcome the weaknesses of viaduct bridges and the non-economic efficiency of underground LRT, the study of near-surface railway systems is in progress. To apply a box structure to the low depth transit, a connection joint to precast modules are very important when applying precast modular structures to replace temporary structures. In this study, wall to wall connections were applied in diverse cases such as rebar connections, guiding structures that were used to fit the verticality of precast walls during construction, and non-reinforcement structures used only for waterstop. Experimental performance verification was carried out for the bending, shear and splitting of the wall to wall connection. Precision of construction joints between wall to wall was identified as a factor that influenced the structural performance of the precast wall. A structure that can serve as a guide during the vertical insertion of a wall is confirmed for the most suitable case, but it will be necessary to modify this structure for detailed cases.

• Computational Structural Engineering
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• v.26 no.2
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• pp.37-42
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• 2013

준공 후 상당한 시간이 지나 내진설계가 되지 않았거나 내진상세가 이루어지지 않은 건물의 부족한 내진성능을 보완하기 위한 방법의 하나로 좌굴이 제한된 가새형 댐퍼를 적용할 수 있다. 이 방법을 적용할 경우, 기존 내진보강법의 불확실성을 줄일 수 있었음에도 불구하고, 댐퍼의 설계과정이 복잡하여 실무에 적용하기 어려웠다. 그러나 본 원고에서는 강성과 강도개념을 적용한 댐퍼의 설계법을 적용함으로써, 실무에서 쉽게 적용할 수 있도록 하였다. 준공된 지 16년이 지난 비틀림 비정형 건물에 대한 내진성능을 평가한 후, 가새형 댐퍼로 보강한 결과는 다음과 같다. (1) 일방향해석결과 나타난 골조별 하중-지붕변위의 관계를 이용하여, 연약골조의 강성을 강한 골조의 강성과 일치시키고, 이 강성비로부터 댐퍼가 부담하는 최적의 내력비율을 정하여 내진보강을 수행한 결과, 가새를 설치한 방향으로는 가새형댐퍼가 비틀림 방지와 연성증대효과를 구조물에 부여하여 성능이 획기적으로 증가하였다. 또한, 그 가새의 직각방향 하중에 대해서도 가새를 설치함으로써 비틀림 강성이 증가하고, 가새와 코어벽체가 인장과 압축으로 횡력에 저항하여 횡저항 성능이 증가하였다. (2) 내진성능이 부족한 비틀림 비정형 건물의 내진성능을 증진시키기 위해 가새형 댐퍼를 적용함에 있어, 댐퍼의 강성을 이용하여 구조체의 비틀림 거동을 최소화하고, 연성을 증진시키는 방법을 체택할 경우, 실무자들이 보다 쉽게 적용할 수 있으면서 그 효과도 상당히 클 것으로 기대된다.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.41-49
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• 2009

Poor compaction of subgrade soil causes low stiffness and bearing capacity of sublayers so that faulting and differential settlements can be generated between new and old pavement surfaces in case of widening works. However, investigation of verifying the reason of producing the defects in the pavements are not performed in detail. In this study, several in-field tests including PMT and PBT were performed for obtaining stiffness of the sublayers in new and old pavements respectively of an widening project. Then, based on the obtained stiffness values and the measured deformations obtained by specially designed tilt meters, the main reasons of generating different deformations between the old and new pavement sections and the relationship between the deformation and stiffness are verified.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.175-182
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• 2021

There have been many instances of damage to buildings with soft stories, and it is important to consider vertically irregular buildings when evaluating the seismic performance of existing buildings. However, because conventional methods do not easily reflect vertical irregularities with sufficient accuracy, it is possible to underestimate or overestimate the seismic performance of buildings with vertical irregularities. This study aims to develop a seismic performance evaluation method for vertically irregular buildings using the stiffness-based soft story ratio (SSR), which is a parameter that represents the ratio of the demand and the capacity for displacement and refers to the ratio of displacement concentration in buildings. The seismic performance evaluation method developed in this study is compared with the conventional seismic performance evaluation method for four piloti buildings, using the first-floor column as a variable. Conventional seismic performance evaluation methods often overestimate the seismic performance for models in which vertical irregularities are maximized. However, results of the proposed seismic performance evaluation method are identical to those from a detailed evaluation for all models. Therefore, it is considered that the proposed seismic performance evaluation method can provide more precise seismic performance evaluation results than conventional methods in the case of piloti buildings, where vertical irregularities are maximized.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.5
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• pp.194-202
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• 2006

In the present study, stiffness prediction methodologies for flat-plate structures were evaluated in comparison with the experimental results on the full-scale slab-column connections of flat-plate structures. The methodologies are as follows: the methodology proposed by Jacob S. Grossman and the methodology proposed by Choi & Song. The former does not predict the stiffness change of the slab-column connection due to the change in the column section shape and the latter overestimates the stiffness when edge length of the column section in the loading direction is long. In the present study, the equation to calculate the effective width of slabs was modified to reflect the effect of the change in the column section shape.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.71-78
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• 2008

In the case of the railway bridges, uplift forces were occurred at the edge of the segments when vehicular loads were applied. These forces caused the compressive and tensile forces in the fastening system. In the past, a structural analysis has been performed to investigate the safety of fastening system which was modeled with one directional spring elements based on the compressive test of fastening system. In this case, the stiffness of the spring element was obtained from experimental study which was conducted by compressive load. Therefore, to perform rational and exact structural analysis, the translational stiffness of the fastening system obtained from the experimental study applied the tensile load and the rotational stiffness should be considered because it was occurred the tensile force as well as the compressive force in fastening system. In this study, an elastic and inelastic experimental study was performed for six specimens. The translational stiffness along the vertical axis of rail and the rotational stiffness along the strong axis of rail were investigated, also structural behavior of the fastening system was analyzed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.331-334
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• 2009

본 논문에서는 계측을 통한 초고층 무량판 구조물의 횡강성 산정식의 유효성을 검정하였다. 초고층 건축물의 풍진동은 건축물의 사용성 평가에 중요한 구조설계요인 중 하나이다. 신뢰성 있는 풍하중 및 풍진동을 얻기위해서는 정확한 고유주기의 예측이 중요하며 고유주기 예측에 오차가 있을 경우 하중을 지나치게 과대평가하게 되는 문제를 유발하게 된다. 본 논문에서는 최근들어 국내에서 본격적으로 증가하고 있는 초고층 무량판 구조시스템의 건축물에 대한 해석 모델링과 실측을 통하여 추정된 무량판 초고층 건물의 동적특성을 바탕으로 구조해석과 동적거동의 계측을 통하여 내풍설계를 위한 횡강성 및 주기를 산정하는 연구를 수행하였다.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.69-76
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• 2010

After obtaining tensile and compressive stiffness as well as shear stiffness of elastomeric seismic isolator experimentally, those stiffness were modeled analytically using nonlinear computer program. To induce tensile stress due to overturning in the seismic isolators of an isolated frame for horizontal force, free vibration simulations generated by large initial displacement were conducted. Since elastomeric seismic isolator is weak for tensile stress, the axial stiffness of isolators shall be included properly in the analytical model to evaluate the uplift phenomenon of elastomeric seismic isolator.