• Magazine of the Korea Concrete Institute
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• v.6 no.1
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• pp.120-130
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• 1994

The purpose of this study is to propose the analytical model for the hysteretic behavior of Reinforced Concrete bearn-column joints under various loading history. Discrete line elernents , YVith inelastic rotational spring was adopted to consider the movement of plastic hinging zone influenced by the details of longitudinal reinforcements. Also hysteretic model was constructed by excluding such variables which can not be utilized in dynamic analysis of Reinforced Concrete. structure that it will be adoptable in two-dimensional inelastic frame ardysis with 6-DOF. From the analysis of previous test results, it was found that stiffness deterioration caused by inelastic hysteretic loadings can be predicted by the functron of basic pinching coefficients, ductility ratio.and yield strength ratio of members. Strength degradation coefficients were newly proposed to explain the difference of inelastic behavior of members caused by spacing ratio of transverse steel and sectlon aspect ratio. The energy dissipation capacities calculated using the analytical model proposed in thls paper show a good agreements w~lh test results by an error of 10~20%.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.37-37
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• 2011

최근 세계적인 지진의 발생과 함께 구조물의 내진성능 평가 및 증진 방법에 대하여 많은 연구가 진행 되고 있다. 특히 교량 구조물의 교각의 경우에는 상부구조의 고정하중 및 활하중을 지반에 전달하여 주는 역할을 하기 때문에, 역으로 지진이 발생하였을 경우 교각의 내진성능에 따라서 교량의 안전도에 많은 영향을 미칠 수 있다. 또한 산악지역이 국토의 70%이상을 차지하는 우리나라의 지형적인 특성상 고교각을 이용한 장대교량의 건설이 필요하며 도시지역의 교통량 증가로 인한 도시고속도로의 건설 등 고가교의 필요성이 점차 증가하고 있다. 그러나 CFT(Concrete Filled Tube)부재의 경우에는 콘크리트가 3축 구속 상태로 존재하지만 자중이 크며 내진 성능이 떨어지는 단점을 가지고 있다. 이러한 단점을 보완하기 위하여 CFT부재의 단면을 중공으로 만듦으로써 부재를 경량화하고 내부 튜브를 삽입하여 내부를 구속 시킨 내부 구속 중공 CFT 부재(Internally Confined Hollow CFT Member, ICH CFT)가 개발되었다. 이는 콘크리트가 내 외부 튜브에 의하여 구속되어 3축 구속 상태로 존재함으로써 콘크리트 중공부로의 취성파괴를 방지하여 연성도 및 강도를 향상시켜주며, 단면의 감소로 인해 재료비를 절감 할 뿐 아니라 자중 감소로 인해 내진 설계에도 유리하다. 현재 내부 구속 중공 CFT 부재에 대한 연구가 많이 진행되고 있지만, 튜브를 삽입함으로써 부재의 중공부로 발생하는 구속력의 특성을 해석적으로 정립한 연구는 미비한 실정이다. 본 연구에서는 압축을 받는 중공 CFT 부재에 내부 튜브를 삽입함으로써 발생하는 콘크리트의 구속력을 해석적 연구를 통하여 수행하였으며, 구속력을 파악하기 위한 평가 방법으로는 구속 콘크리트의 중공비와 직경, 외부튜브의 두께, 내부튜브의 두께 등으로 평가하였다. 해석적 연구 결과, 내부 튜브를 삽입함으로써 발생되는 외부 구속력은 이론적 수식에 의한 구속 응력값과 비슷한 값을 가지지만 내부로 발생하는 구속력은 이론적 수식에 의한 구속 응력값에 도달하지 못하는 것을 확인할 수 있었다.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.11-18
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• 2010

In this study, a procedure of performance-based design for the seismic retrofit of reinforced concrete columns strengthened by steel jackets has been presented. In order to predict the target displacement of retrofitted columns, a nonlinear analysis of reinforced concrete columns retrofitted with steel jackets has been developed based on a segmental model with the fiber cross-sectional approach. The seismic displacement level of retrofitted columns is estimated both by the direct displacement-based design method and by the displacement coefficient method. In examples of seismic retrofitted columns, the current seismic retrofit procedure gives good results in improvements of displacement levels and displacement ductilities of retrofitted columns.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.301-304
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• 2008

The stair joints constructed with prefabricated system are general method doing structure design at hinge. If you regarded joints to come in contact with a flight of stairs and a slope of stairs as hinge, the moment performance of joints is not in the least moment, so as the bending moment of the stair case is increased, the reinforcement increase. Also the use is decreased because increasing the joint damage of the vibration & fatigue load. No less the reason constructed with pin the stair joints because the construction efficiency of field work is useable. Recently, they are considering the construction efficiency, while the semi-rigid detail for bending performance of joints is proposed, but for now they don't reflect the detail. Therefore, we proposed that reflecting the method at design semi-rigid joints. We compared the moment performance with the stair joints designed at the rigid joints, semi-rigid joints and pin joints. The nonlinear behavior of staircase core statically indeterminate structure. The result of research is that a bending stiffness modulus bring to reflect the semi-rigid performance, the performance of the semi-rigid joint is better than pin joints, and that is judged the system better seismic and vibration performance because have excellent ductility more than rigid joint.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.715-723
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• 2007

A displacement-based seismic design procedure was proposed for mid-to-low-rise steel moment frames. The proposed method was totally different from the current R-factor approach in that it directly uses available connection rotation capacity as a primary design variable. To this end, the relationship between available connection rotation capacity and seismic response modification (R factor) was established first; this relationship has been a missing link in current ductility-based design practice. A step-by-step displacement-based iterative design procedure was then proposed and verified using inelastic dynamic analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.4
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• pp.387-394
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• 2000

The nonlinear modal interaction of an autoparametric system under a broadband random excitation is investigated. The specific system examined is an autoparametric vibration absorber with internal resonance, which is typical of many common structural configurations. By means of Gaussian closure scheme the dynamic moment equations explaining the random responses of the system are reduced to a system of autonomous ordinary differential equations of the first and second moments. In view of equilibrium solutions of this system and their stability we examine the system responses. We could not find the destabilizing effect of damping, which was reported in References (18) and (20). The saturation phenomenon, which is well known in deterministic nonlinear system, did not take place lot this system subject to broadband random excitation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.309-316
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• 2011

Canoes are usually made from wood or FRP. However, today environment-friendly materials are preferred, and hulls made of FRP are prohibited in some countries. Polyethylene can be recycled and so is suitable for synthetic canoe construction. We used 3D Boat-Design to determine the hydrostatic properties of the canoe. Flow-structure coupled analysis was performed using ANSYS Workbench R12.1. The hull pressure and passenger weight were considered as canoe loading factors. The key parameters for the canoe are the design variables. The constraints are as follows: (1) The maximum stress must not exceed 50% of the polyethylene yield stress; and (2) the canoe weight must not exceed 50 kg. The optimal structural conditions were obtained by the response optimization process. The components of the canoe hull were manufactured from polyethylene pipes and joined by thermal fusion methods. Tests showed that the polyethylene canoe had better performance than existing canoes.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.6
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• pp.25-34
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• 2003

Recently, performance-based analysis/design methods such as the capacity spectrum method and the direct displacement-based design method were developed. In these methods, estimation of energy dissipation capacity of RC structures depends on empirical equations which are not sufficiently accurate, On the other hand, in a recent study, a simplified method for evaluating energy dissipation capacity was developed. In the present study, based on the evaluation method, a new seismic design method for flexure-dominated RC walls was developed. In determination of earthquake load, the proposed design method can address variations of energy dissipation capacity with design parameters such as dimensions and shapes of cross-sections, axial force, and reinforcement ratio and arrangement, The proposed design method was compared with the current performance-based design methods. The applicability of the proposed method was discussed.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.133-142
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• 2014

Double split tee connection is a full strength-partial restrained connection that suitable for ordinary moment frame and special moment frame which demonstrates behavior characteristics depending on the stiffness ratio of columns and beams, changes in the geometric shape of the T-stub, number of fasteners and effect of panel zone. For the double split tee connection to ensure structurally safe behavior, it needs to exhibit sufficient strength, stiffness and ductile capacity. This study sought to investigate the effects of the moment-rotation angle relationship of the double split tee connection and to evaluate the initial rotational stiffness of the double split tee connection depending on changes in the geometric shape of the T-stub. To this end, two different double split tee connection specimens are experimented which designed to change geometric parameter values (${\alpha}^{\prime}$) of the T-stub, and a three-dimensional finite element analysis was performed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.379-384
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• 2014

The most critical rotating parts of a gas turbine engine are turbine blades and disc, given that they must operate under severe conditions such as high turbine inlet temperature, high speeds, and high compression ratios. Owing to theses operating conditions and high rotational speed energy, some failures caused by turbine disks and blades are categorized into catastrophic and critical, respectively. To maximize the margin of structural integrity, we aim to optimize the vulnerable area of disc-blade interface region. Then, to check the robustness of the obtained optimized solution, we evaluated structural reliability under uncertainties such as dimensional tolerance and fatigue life variant. The results highlighted the necessity for and limitations of optimization which is one of deterministic methods, and pointed out the requirement for introducing reliability-based design optimization which is one of stochastic methods. Thermal-structural coupled-filed analysis and contact analysis are performed for them.