• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.127-135
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• 2019

The seismic performance of non-ductile reinforced concrete (RC) frame retrofitted with H-beam frame and cast expansive mortar into joint between existing RC frame and H-beam frame is investigated experimentally and analytically. RC frames considered in the study contain non-ductile reinforcement details of low-rise school building constructed in Korea before 1988. The tests were conducted on half-scale specimens simulating the lower frame assemblages of a typical school building. Two one-bay, one-story RC frames with and without retrofitting with H-beam frame and expansive joint mortar were tested to failure. Test and analysis results indicated that seismic strengthening using H-beam and expansive joint mortar significantly improved the lateral strength and stiffness of non-ductile RC frame without installing anchor bolts to fit H-beam frame into existing RC frame. The effectiveness of seismic strengthening technology proposed in the study for non-ductile RC frame was verified experimentally and analytically.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1129-1134
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• 2007

Payload fairing protects satellites and electrical equipments from the external environment. Payload fairing is jettisoned before satellite separation. Assembly frame for the separation of payload fairing were assembled with shear bolts. The role of shear bolts is to support structural load during flight and they are cut by explosion of pyro. The assembly frame which is connected by shear bolts is separated after the cutting of shear bolts. In this paper, structural tests and analysis were done for the design of the shear bolt. Compression, bending and shear load apply to the hardware including assembly frame. Test results showed that design of the shear bolt satisfied both structural strength for the support of flight load and required low strength for the cutting of shear bolts.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.742-745
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• 2010

본 논문은 초고층구조물의 해석방법으로 탄성변형과 아울러 시간의존성을 가진 크리프와 건조수축에 의한 비탄성변형을 고려한 비선형 시공단계 해석법을 제시한다. 기존의 초고층구조물 해석에서 주로 행하는 기둥 축소량 해석은 실무자의 경험과 프로그램을 통한 간략화에 맞추어져 있다. 이는 실제 시공 시 발생하는 구조해석 요소들을 충분히 반영하지 못하여 계산 값과 실제 값 사이에 오차가 발생된다. 비선형 시공단계 해석은 실제 시공 때 발생되는 해석변수들을 고려한 단계별 해석의 수행이 가능하며, 시간의 의존성을 가진 creep과 shrinkage의 효과를 함께 고려하여 일괄해석의 문제점을 구조해석 단계에서 실제상황에 가까운 해석을 가능하게 할 수 있다. 이를 위해 시공단계해석이 가능한 범용 프로그램을 이용한 50층 규모의 3차원 골조 프레임 모델 예제 해석을 통하여 기존 해석법들과의 비교, 분석으로 시간의 의존성을 고려한 시공단계해석의 필요성을 제시한다. 본 논문에는 범용프로그램인 SAP2000(ver.14)와 CEB-FIP모델 코드를 사용 하였다.

• Journal of Korean Society of Steel Construction
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• v.19 no.1
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• pp.29-41
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• 2007

Structural design, like other complex decision problems, involves many trade-offs among competing criteria. Although mathematical programming models are becoming increasingly realistic, they often have design limitations, that is, there are often relevant issues that cannot be easily captured. From the understanding of these limitations, a decision-support system is developed that can generate some useful alternatives as well as a single optimum value in the optimization of steel frame structures. The alternatives produced using this system are "good" with respect to modeled objectives, and yet are "different," and are often better, with respect to interesting objectives not present in the model. In this study, we created a decision-support system for designing the most cost-effective moment-resisting steel frame structures for resisting lateral loads without compromising overall stability. The proposed approach considers the cost of steel products and the cost of connections within the design process. This system makes use of an optimization formulation, which was modified to generate alternatives of optimum value, which is the result of the trade-off between the number of moment connections and total cost. This trade-off was achieved by reducing the number of moment connections and rearranging them, using the combination of analysis based on the LRFD code and optimization scheme based on genetic algorithms. To evaluate the usefulness of this system, the alternatives were examined with respect to various design aspects.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.9-20
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• 1999

A method is proposed to estimate the joint damages of a steel structure from modal data using the neural networks technique. The beam-to-column connection in a steel frame structure is represented by a zero-length rotational spring of the end of the beam element, and the connection fixity factor is defined based on the rotational stiffness so that the factor may be in the range 0~1.0. Then, the severity of joint damage is defined as the reduction ratio of the connection fixity factor. Several advanced techniques are employed to develop the robust damage identification technique using neural networks. The concept of the substructural indentification is used for the localized damage assessment in the large structure. The noise-injection learning algorithm is used to reduce the effects of the noise in the modal data. The data perturbation scheme is also employed to assess the confidence in the estimated damages based on a few sets of actual measurement data. The feasibility of the proposed method is examined through a numerical simulation study on a 2-bay 10-story structure and an experimental study on a 2-story structure. It has been found that the joint damages can be reasonably estimated even for the case where the measured modal vectors are limited to a localized substructure and the data are severely corrupted with noise.

• Computational Structural Engineering
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• v.4 no.3
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• pp.89-97
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• 1991

Conventional aseismic design methods of R/C frame all but disregard the state of damage over the entire building frame. This paper presents an automated damage-controlled design method for R/C frames which aims at an uniform energy dissipation rate throughout the building frame, so that the resulting damage is uniformly distributed as much as possible over all element. The accuracy of the basic hystertic model and the damage model for R/C members is verified by reproducing the experimental load-deformation curves of one-bay one-story frames. Application of this design method to various frame structures indicate that 1) regardless of the structural properties or input earthquake characteristics, damage-controlled frames generally survive more severe earthquake excitations and suffer less damage than conventionally designed frames, and 2) member yielding strength in the lower stories of damage-controlled frames is larger than that for conventionally designed frames, while the trend is opposite in the upper stories.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.4
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• pp.369-376
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• 2016

In this study, a numerical analysis framework for investigating the nonlinear behavior of structures under fire conditions is presented. In particular, analysis procedure combining fire-driven flow simulation and thermo-mechanical analysis is discussed to investigate the mechanical behavior of fire-exposed representative volume structures made of steel and concrete, respectively. First of all, fire-driven flow analysis is conducted using Fire Dynamics Simulator(FDS) in a rectangular parallelepiped domain containing the structure. The FDS simulation yields the time history of temperature on the surface of the structure under fire conditions. Second, mechanical responses of the fire-exposed structure with respect to prescribed uniformly distributed loads are calculated by a coupled thermo-mechanical analysis using the time-varying surface temperature as boundary conditions. Material nonlinearities of steel and concrete have been considered in the thermo-mechanical analysis. A series of numerical results are presented to demonstrate the feasibility of the multiphysics structural fire analysis for investigating the structural behavior under fire conditions.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.519-521
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• 2000

최근전산 환경은 통합되는 개방형 시스템으로 변모하고 있는데, 클래스 라이브러리의 재사용이 재사용을 향상시키지 못하고 있다. 이로 인한 라이브러리 습득에 많은 시간과 노력이 가중되고 개발시간이 길어진다. 따라서, 본 논문에서는 객체지향 프레임워크를 잘 사용하여 재사용할 수 있도록 잘 관리하는 저장소를 제안한다. 객체지향 소프트웨어 공학 프로세스에 의해 생성되는 산출물을 객체 형태로 통합 관리함으로서 프레임워크 재사용을 쉽게 할 수 있고, 객체들을 효율적으로 관리해 주고, 특정한 도메인에서 프레임워크를 재사용하여 새로운 어플리케이션을 개발할 때 시간을 단축하기 위해서 통합 객체 관리 저장소를 제안한다. 이 모델은 프레임워크 클래스 계층 구조 및 클래스 상호간의 상호작용 정보를 유기적으로 관리하고 통합할 수 있다.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.23-24
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• 2000

프레임에 그물감을 부착하여 구성되어 있는 가두리 시설은 대부분 수면에 반잠수 상태로 부유되어 계류되어 있기 때문에 파랑이 작용하면 운동을 하게 되며, 특히 파도가 높은 해역에서는 파에 의해 구조물이 연직 방향으로 크게 운동을 하여 어류에 나쁜 영향을 미칠 뿐만 아니라 해상 작업을 하는 인부에게도 매우 위험하다. 이와 같은 문제점을 해결하기 위해서는 파랑에 의한 운동이 최소화되도록 구조물을 설계해야 한다. (중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.87-87
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• 2004

최근 철도 차량은 안전성, 정시성, 대량 수송성이 우수하여 수송수요가 증가하고 있으며, 열차운행 횟수의 증가와 차량의 고속화로 운행조건이 가혹해짐에 따라 이에 대한 절대적인 안전성과 높은 신뢰성이 요구되고 있다. 철도차량과 같이 반복하중이 연속적으로 작용하는 구조물의 설계에 있어서는 구조물의 사용 환경이나 재료의 피로특성을 최우선의 고려사항으로 간주해야 한다. 실제로 철도차량의 대차 프레임은 맞대기 용접으로 제작되어 있으며, 용접부에서 파손이 발생하고 있다.(중략)