• Structural Engineering and Mechanics
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• v.2 no.1
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• pp.81-94
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• 1994

It is well recognized that structures designed to resist strong ground motions should be able to withstand substantial inelastic deformations. A simple procedure has been developed in this paper to monitor the dynamic earthquake response (time-history analysis) of both steel and concrete multistorey buildings in the inelastic range. The building is treated as a shear beam model with three degrees of freedom per floor. The entire analysis has been programmed to run on a microcomputer and can output time histories of displacements, velocities, accelerations and member internal forces at any desired location. A record of plastic hinge formation and restoration to elastic state is also provided. Such information can be used in aseismic analysis and design of multistorey buildings so as to control the damage and optimize their performance.

• Steel and Composite Structures
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• v.13 no.1
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• pp.1-13
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• 2012

In this study, a new structural bracing system named 'Hat Knee Bracing' (HKB) is presented. In this structural system, a special form of diagonal braces, which is connected to the knee elements instead of beam-column joints, is investigated. The diagonal elements provide lateral stiffness during moderate earthquakes. However the knee elements, which is a fuse-like component, is designed to have one plastic joint in the knee elements for dissipation of the energy caused by strong earthquake. First, a suitable shape for brace and knee elements is proposed through elastic studying of the system and several practical parameters are established. Afterward, by developing applicable and highly accurate models in Drain-2DX, the inelastic behavior of the system is carefully considered. In addition, with inelastic study of the new bracing system and comparison with the prevalent Knee Bracing Frame system (KBF model) in nonlinear static and dynamic analysis, the seismic behavior of the new bracing system is reasonably evaluated.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.3
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• pp.121-127
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• 1998

For the seismic design of bridges in Korea classified as the low to moderate seismic zones, the design concepts provided in the Standard Specification for Highway Bridges, Division I-A: Seismic Design, are adopted, which is basically developed for the strong seismic zones by AASHITO. Accordingly, the design procedures provided for the low to moderate seismic zones are simplified too much to fulfill the purpose of the seismic design. In this paper the design procedures given for the low to moderate seismic zones in the Standard are summarized and discussed in view of the seismic design purpose. From the discussion results some revisions are proposed as conclusions for the reasonable a, pp.ication of the Standard for bridges located in the low to moderate seismic zones.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1533-1536
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• 2003

Dynamic model of the rubber-tired AGT light rail vehicle. various load and boundary conditions between vehicle and infrastructures(running track. guidance rail) were defined to analyze vehicular dynamic behaviors occurred by inclement weather(strong wind and earthquake). The dynamic analysis were performed by using a commercialized software RecurDyn. whose results for the magnitudes of wind and earthquake showed the resultant forces and accelerations between car body and bogie, or bogie guidance frame and infrastructures in the various track conditions(straight or curved tracks) and train velocities. Based on these results, speed limitation of tile vehicle were proposed to ensure system stability and passengers safety.

• Smart Structures and Systems
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• v.14 no.4
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• pp.501-516
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• 2014

The rocking pier system (RPS) allows the columns to rock on beam or foundation surfaces during the attacks of a strong earthquake. Literatures have proved that seismic energy dissipated by the RPS through the column impact is limited. To enhance the energy dissipation capacity of a RPS bridge substructure, frictional hinge dampers (FHDs) were installed and evaluated by shaking table tests. The supplemental FHDs consist of two brass plates sandwiched by three steel plates. The strategy of self-centering design is to isolate the seismic energy by RPS at the columns and then dissipate the energy by FHDs at the bridge deck. Component tests of FHD were first conducted to verify the friction coefficient and dynamic characteristic of the FHDs. In total, 32 shaking table tests were conducted to investigate parameters such as wave forms of the earthquake (El Centro 1940 and Kobe 1995) and normal forces applied on the friction dampers. An analytical model was also proposed to compare with the tested damping of the bridge sub-structure with or without FHDs.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.311-319
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• 2001

Recently, the number of seismically isolated bridges increased suddenly since the occurrence of strong earthquakes. However, because isolator lies between pier and girder, the response of the superstructure of seismically isolated bridge may be magnified and induce risk of unseating girder Consequently, the response of girder constitutes a crucial factor in designing bridge. In the case of frictional bearing, the inherent nonlinearity makes the use of former linear response spectrum unable to estimate the maximum response of the bearing, and nonlinear tlme history analysis shall be applied. In this paper, nonlinear response spectrum considering frictional element is established, and simple analysis method using such nonlinear spectrum is proposed to estimate the maximum response of the superstructure.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.258-265
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• 2002

Most structures are expected deform nonlinear and inelastic behavior when subjected to strong ground motion. Nonlinear time history analysis(NTHA) is the most rigorous procedure to compute seismic performance in the various inelastic analysis methods. But nonlinear analysis procedures necessitate more reliable and practical tools for predicting seismic behavior of structures. Some building codes propose the capacity spectrum method. This method is the concept of an equivalent linear system, wherein a linear system having reduced stiffness and increased damping is used to estimate the response of the nonlinear system. This procedure are conceptually simple, but the iterative procedure is time-consuming and may sometimes lead to no solution or multiple solutions. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for mixed building structure.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.43-50
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• 2002

부지고유의 강지진동모사를 위해 한반도 남부의 지각감쇠(Q)에 대한 두 가지 특성을 비선형 역산을 통해 규명하였다. 한 특성은 한반도 남부의 주요 지체구조구 및 특정 주향각에 대한 Q의 이방성이고 다른 특성은 Q의 수평방향으로의 공간적 변화 특성이다. 0의 이방성은 주향에 평행한 Q와 이에 수직한 Q의 비로 정의되었다. 사용된 지진자료는 190개 지진에 대한 3,400개 기록의 푸리에스펙트럼으로서 기록의 파선 분포는 한반도 남부 대부분을 조밀하게 덮었다. 역산 방법은 Levenberg-Marquardt 비선형역산 방법을 보다 안정화시킨 수정된 Levenberg-Marquardt 방법이 사용되었으며 기존에 도출된 광역적인 지진동파라미터를 초기해로 활용하였다. 역산 결과 국내의 중요 지체구조구 중 소백산육괴와 경상분지는 서로 다른 방향의 강한 Q 이방성을 나타내었으며 Q의 공간적 분포는 지진발생위치와 매우 밀접한 상관관계를 보여주었다

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.349-356
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• 2002

Anticipating potential strong earthquakes, bracing dampers for better seismic performance are being developed in Korea, while similar ones are already developed in other countries. But, there are lack of relevant research on Slender Brace Dampers rather than hysteretic dampers, whose concept is also inappropriate for rehabilitation existed slender braced frame. For the development of Slender Brace Damper in slender braced frame, this research investigates Slender Brace Damper possessing various shapes of hyteretic damper through performing experimental test under cyclic loadings. As a result at this paper, Energy dissipation of test specimens (H35B20PS, H35B20TS, H20B60PS) are superior.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.37-42
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• 2003

We have analyzed the characteristics of the sea surface winds and wind waves near the Korean marginal seas on the basis of prediction results of the sea surface winds from MM5/KMA model, which is being used for the operation system at the Korea Meteorological observation buoy data to verify the model results during Typhoon events. The correlation coefficients between the models and observation data reach up to about 95％, supporting that these models satisfactorily simulate the sea surface winds and wave heights even at the coastal regions. Based on these verification results, we have carried out numerical experiments about the wave modulation. When there exist an opposite strong current for the propagation direction of the waves or wind direction, wave height and length gets higher and shorter, and vice versa. It is proved that these modulations of wave parameters are well generated when wind speed is relatively week.