• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.109-119
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• 2004

A design procedure for velocity-dependent supplemental dampers, such as viscous or viscoelastic dampers, required to meet the desired performance objectives was developed using displacement spectra. The amount of supplemental damping required to satisfy given performance limit state was obtained first from the nonlinear static procedure using displacement spectra, then dampers were appropriately distributed throughout the stories to realize the required damping. The proposed method was applied to multi-story steel frames, and the structures were analyzed by time history analysis to validate the accuracy of the design procedure. According to the analysis results the maximum displacements of the model structures retrofitted by the supplemental dampers turned out to be restrained well within the given target values.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.733-747
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• 2017

In the shallow tunnel, the surrounding ground could be loosened and deformed, which could be the cause of stress change in the ground. Terzaghi has clarified the development of a ground arching induced by the deformation of a tunnel crown in the trap door tests. However, he considered only the case in which that the tunnel crown deformed uniformly. He did not consider the effect of deformation shapes. Therefore, the relation between the shape of the ground relaxation above the tunnel crown and the deformation shape of the tunnel crown is not clear yet. In this study, model tests were performed for the three types of the tunnel crown, such as uniform, concave and convex shapes. As results, it was found that the vertical load would be transferred in various types depending on the deformation shapes of the tunnel crown.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.521-528
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• 1994

레이저광의 우수한 가간섭성으로 인해서 거친표면으로 부터 확산된 광에서도 간섭현상을 볼 수가 있다, 이와 같은 레이져광의 독특한 특성으로 인해 나타나는 스페클은 광학적인 간섭계를 사용하여 광을 확산적으로 반사시키는 물체의 변형과 변위, 진동 등을 비접촉적으로 측정 할수 있게 되었다.이와같은 측정법으로써 Holography 간섭법, Speckle 간섭법, Speckle 사집법등이 있으며 비록 이러한 측정법들이 독립적으로 발전되었다 할지라도 기본적인 광학적인 배치와 함수들에 있어서는 유사한 특징을 가지고 있다. 따라서 본 연구에서는 주로 면내변형을 측정하기위한 스페클간섭법에 있어서의 스페클 사이즈와 그에 따른 측정 한계를 확인할 것이다.

• Geotechnical Engineering
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• v.14 no.6
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• pp.81-92
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• 1998

A beam on elasto-plastic foundation modeling of soldier pile and woodlagging tieback walls or anchored walls was developed and tested. An instrumented full scale tieback wall in sand was constructed at the National Geotechnical Experimentation Bite located on Texas A&M University. The experimental earth pressure deflection relationship (p-y curves) was developed from the measurements. The construction sequence was simulated in the proposed method. The conceptual methodology of an anchored wall design was introduced by using the proposed method. The proposed method was evaluated with the measurements of case histories in sand and clay. A parametric research was performed to study the most influencing factors for the proposed method. It is concluded that the proposed method represents a significant improvement on the prediction of bending moments and deflections of the properly designed walls.

• Journal of the Korean Society for Precision Engineering
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• v.1 no.1
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• pp.23-29
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• 1984

소성역학에 의해서 소성가공중의 현상을 해석하여 제품의 형상, 강도, 잔유응력, 가공력, 가공한계 및 결함의 발생등을 견적하고 이것에 의해 가공기계의 강도, 강성 및 제어량등이 결정된다. 또 재질에 대한 지침이 얻어진다. 탄성론이나 소성론에서 경계치 문제는 응력젼위방정식, 응력의 경계조건, 변위에 관한 변위 스트레인 관계식과 변위의 경계조건, 그리고 응력과 스트레인을 관계시 키는 구성방정식으로 되어 있는 기초방정식으로 구성된다. 문제의 구성방정식은 재료의 거동이 매우 복잡하기 때문에 실제의 거동을 충실히 표시 할 수 없다. 재료의 이방성, 유한도형, 이방성주축의 회 전, 가공경화, 고온, 고속가공 등에 의해서 재료의 변형거동은 매우 복잡해진다. 이상의 정량적 고찰 과 전위 또는 결정의 슬립모델과 같은 정성적 고찰도 있다.

• Journal of the Korean GEO-environmental Society
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• v.15 no.1
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• pp.43-51
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• 2014

Angular distortion due to differential settlement is one of the critical factors which influences on the stability and serviceability of a structure. The angular distortion criterion proposed by Bjerrum is generally used in practice. However, the measurement system used in field especially a road embankment site did not properly represent the angular distortion of a structure. The problem was related to the shortage and not proper installation of measurement gauges, and the incorrect understanding of the basic concept of angular distortion in interpretation of measurement data. These things were reveled by analyzing the measured data in the road embankment site. An improved measurement system has been suggested as a so-called "relative displacement measurement system" between columns with automatic measurement.

• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.551-558
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• 2015

Lateral displacement in the most complex-shaped tall buildings is caused by eccentric gravity loads which are induced by the difference in location between a center of mass and a center of stiffness. The lateral displacements obtained from analysis, using conventional procedures, are prone to overestimate the actual values because much of realignment efforts made during construction phase are ignored. In construction sequence analysis, the self-leveling of slab and the verticality of columns/walls could be considered at each construction stage. Moreover, the displacement compensation can be achieved by manual process such as re-centering - locating to global coordinates through surveying. Because the lateral displacement increases with the building height, it is necessary to set up adjustment plan through construction stage analysis in advance in order to result in displacements less than the allowable limits. Because analytical solution includes lots of assumptions, the pre-adjusting displacement should be reasonably controlled with considerations for the uncertainty due to these assumptions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6C
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• pp.321-329
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• 2009

Laboratory compressive test was conducted on 6 different types of rock in order to investigate the characteristic of critical strain under uniaxial and triaxial stress condition. The results of uniaxial compressive test mostly ranged within 1~100MPa, the critical strain was also located between 0.1~1.0%. Therefore the results distributed within the upper and lower boundary proposed by Sakurai (1982). And the failure/critical strain ratio (${\varepsilon}_f/{\varepsilon}_0$) showed between 1.0~1.8 value depending on the uniaxial compressive strength. The results of critical strain by triaxial compressive test showed below 0.8% value for all test, the M value calculated from uniaxial and triaxial compressive test results ranged 1.0~8.0 for most of rock specimens. It is concluded that failure strain (${\varepsilon}_{f3}$) of rock mass, which is in triaxial stress condition is larger than the results of uniaxial stress condition (${\varepsilon}_{f1}$) by 1.0~8.0 times and value showed 1.0~1.8 larger value than critical strain (${\varepsilon}_{01}$). Therefore it is a conservative way for rock tunnel to use critical strain (${\varepsilon}_{01}$) calculated from a uniaxial compressive strength on tunnel displacement monitoring.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.2
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• pp.115-123
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• 1989

A computer program evaluating the pile downdrag is developed using the conventional elastic solid method. Modification of the conventional method has been performed by introducing the concept of critical relative displacement. A simple transfer function method which employes the critical relative displacement as a pile-soil slip criterion and calculates downdrag by Mohr-Coulomb equation, has also been developed. The results of three methods are all found to be in good agreement with field observations. When they are applied to a centrifuge modeling problem of pile downdrag to predict its result, however, diverse answers are obtained. Overall, the simple transfer function method developed in this study seems to be the most effective in the evaluation of pile downdrag, considering the quality of its result and its efficiency in computation.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.3 s.43
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• pp.23-32
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• 2005

Torsional behavior of eccentric structure under seismic leading may cause the stress and/or deformation concentration, which arouse the failure of the structure in an unexpected manner. This study suggests D-R relationship which shows the overall displacement and rotation of the system based on the ultimate displacement capacity of the each lateral load resistant member. Using the suggested D-R relationship and displacement spectrum, the seismic assessment is conducted and verified in comparison with the time history analysis result. Multi-level seismic assessment Is considered which takes multiple seismic hazard levels and respective performance levels into account. Finally, based on the seismic assessment result, seismic rehabilitation process is presented. In this research, two rehabilitation methods are considered. One is done by means of stiffening/strengthening the seismic resistant members, and the other is based on the member ductility. Especially, in the first method, to optimize the rehabilitation result, the rehabilitation problem is modeled as an optimization problem, and solved using BFGS quasi-Newton optimization method.