• 한국전산구조공학회논문집
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• 제32권6호
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• pp.425-434
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• 2019

연약지반이 두껍고 다양한 지층으로 구성된 지역에 건설되는 단일형 현장타설말뚝 교량은 다양한 지층을 통해서 단일형 말뚝으로 입력되는 지반운동에 대해서 내진안전성을 확보하는 것이 중요하다. 본 연구에서는 설계지반운동에 부합되는 다수의 인공합성지진을 생성하여 이를 암반의 입력지반으로 하여 지반해석을 수행하여 각 지층에서의 지반가속도이력을 산정하였다. 이 가속도이력을 이용하여 각 지층의 지반을 등가스프링으로 모델화하고, 각 지층에서의 가속도시간이력을 입력지반운동으로 하는 다지점 가진 지진해석을 수행하였다. 연약층의 비선형거동특성으로 입력지반운동의 세기는 크게 증폭되지 않아서 교량은 탄성영역 내에서 거동하였다. 한편, 특정 지층에서 산정된 가속도이력을 모든 지반스프링에 동시에 입력하면 응답이 감소하였다. 따라서, 다지점가진 해석을 수행하지 않으면 이러한 형식의 교량의 내진성능을 과대평가할 수 있다.

• 한국응용과학기술학회지
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• 제35권3호
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• pp.905-913
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• 2018

본 연구는 필라테스 동작 시 폼롤러의 적용과 움직임에 따른 몸통과 하지의 근활성도 차이를 알아보는 것이 목적이다. 피험자로 남자 8명을 선정하여 필라테스 네발자세, 교각자세, 코어컨트롤 동작을 매트위에서 정적동작, 폼롤러 위에서 정적동작, 폼롤러 위에서 동적동작으로 무선배정하여 1주 간격으로 수행하였다. 각 동작의 수행 시 척추세움근, 배곧은근, 배바깥빗근, 중간볼기근, 넙다리두갈래근과 넙다리곧은근의 근활성도를 측정하여 일원분산분석으로 분석하였다. 유의수준은 ${\alpha}=.05$로 설정하였다. 첫째, 네발기기 동작에서 폼롤러 동적동작에서는 배곧은근, 배바깥빗근, 중간볼기근, 넙다리두갈래근의 근활성도가 높게 나타났으며(p<.001)(p<.05), 폼롤러 정적동작에서는 넙다리곧은근의 근활성도가 높게 나타났다(p<.001). 둘째, 교각자세 동작에서 폼롤러 동적동작에서는 넙다리두갈래근의 근활성도가 높게 나타났다(p<.001). 셋째, 코어컨트롤 동작에서 폼롤러 동적 동작에서는 배곧은근, 척추세움근, 중간볼기근의 근활성도가 높게 나타났으며(p<.001)(p<.01), 정적 동작에서는 배바깥빗근의 근활성도가 높게 나타났다(p<.05). 필라테스 운동시 근활성도를 고려하여 방법과 난이도를 적용하면 더욱더 효과적일 것이라 사료된다.

• Wind and Structures
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• 제20권2호
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• pp.191-211
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• 2015

Several frameworks for the dynamic analysis of wind-vehicle-bridge systems were presented in the past decade to study the safety or ride comfort of road vehicles as they pass through bridges under crosswinds. The wind loads on the vehicles were generally formed based on the aerodynamic parameters of the stationary vehicles on the ground, and the wind loads for the pure bridge decks without the effects of road vehicles. And very few studies were carried out to explore the dynamic effects of the aerodynamic interference between road vehicles and bridge decks, particularly for the moving road vehicles. In this study, the aerodynamic parameters for both the moving road vehicle and the deck considering the mutually-affected aerodynamic effects are formulized firstly. And the corresponding wind loads on the road vehicle-bridge system are obtained. Then a refined analytical framework of the WVB system incorporating the resultant wind loads, a driver model, and the road roughness in plane to fully consider the lateral motion of the road vehicle under crosswinds is proposed. It is shown that obvious lateral and yaw motions of the road vehicle occur. For the selected single road vehicle passing a long span bridge, slight effects are caused by the aerodynamic interference between the moving vehicle and deck on the dynamic responses of the system.

• Wind and Structures
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• 제7권6호
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• pp.421-447
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• 2004

This paper presents a time domain approach for predicting buffeting response of long suspension bridges under skew winds. The buffeting forces on an oblique strip of the bridge deck in the mean wind direction are derived in terms of aerodynamic coefficients measured under skew winds and equivalent fluctuating wind velocities with aerodynamic impulse functions included. The time histories of equivalent fluctuating wind velocities and then buffeting forces along the bridge deck are simulated using the spectral representation method based on the Gaussian distribution assumption. The self-excited forces on an oblique strip of the bridge deck are represented by the convolution integrals involving aerodynamic impulse functions and structural motions. The aerodynamic impulse functions of self-excited forces are derived from experimentally measured flutter derivatives under skew winds using rational function approximations. The governing equation of motion of a long suspension bridge under skew winds is established using the finite element method and solved using the Newmark numerical method. The proposed time domain approach is finally applied to the Tsing Ma suspension bridge in Hong Kong. The computed buffeting responses of the bridge under skew winds during Typhoon Sam are compared with those obtained from the frequency domain approach and the field measurement. The comparisons are found satisfactory for the bridge response in the main span.

• Earthquakes and Structures
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• 제10권3호
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• pp.645-667
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• 2016

The 750 m long "De Bosset" bridge in the Cephalonia Island of Western Greece, being the area with the highest seismicity in Europe, was constructed in 1830 by successive stone arches and stiff block-type piers. The bridge suffered extensive damages during past earthquakes, such as the strong M7.2 earthquake of 1953, followed by poorly-designed reconstruction schemes with reinforced concrete. In 2005, a multidisciplinary project for the seismic assessment and restoration of the "De Bosset" bridge was undertaken under the auspices of the Greek Ministry of Culture. The proposed retrofitting scheme combining soil improvement, structural strengthening and reconstruction of the deteriorated masonry sections was recently applied on site. Design of the rehabilitation measures and assessment of the pre- and post-interventions seismic response of the bridge were based on detailed in-situ and laboratory tests, providing foundation soil and structural material properties. In-situ inspection of the rehabilitated bridge following the strong M6.1 and M6.0 Cephalonia earthquakes of January 26th and February 3rd 2014, respectively, revealed no damages or visible defects. The efficiency of the bridge retrofitting is also proved by a preliminary performance analysis of the bridge under the recorded ground motion induced by the above earthquakes.

• 한국도로학회논문집
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• 제13권4호
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• pp.123-132
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• 2011

본 논문의 목적은 인접차로에서 동시에 주행하는 차량재하의 확률과 실제 차량의 중량을 고려하여 합리적인 다차로 재하계수를 제시하는 것이다. 차량동시재하의 확률은 국내 여러 곳에서 촬영한 비디오영상으로부터 분석되었으며 중차량의 중량은 국내 두 곳에서 Weigh-In-Motion시스템으로부터 계측한 자료를 이용하였다. 이 두 자료를 대표적인 2차로교량과 5차로교량에 각각 적용하여 다차로재하계수를 계산하였다. 또한 본 논문에서 제시한 동시재하확률 및 WIM자료의 중량이 국내의 지역별 특성을 대표하는 값으로 가정하여 다차로재하계수의 통계적인 특성을 산출하였다. 본 논문의 결과는 국내외의 교량 설계기준과 비교하였으며 그 결과 현행 국내의 도로교설계기준의 값보다는 작고, 유로코드 및 AASHTO LRFD기준보다는 큰 값을 나타냈으며 전체적으로 캐나다의 설계기준과 유사한 값을 보이는 것으로 나타났다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.380-385
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• 2008

3 DOFs model for the collision analysis of a bridge super-structure and a super-structure of the navigating vessels were proposed and analyzed. The collision event between the super-structure of vessel and the super-structure of bridge are different from the normal collision event that collided at sub-structure of bridge. Because of its moment arm, the stability force of vessel could affect to the collision behaviors. To consider this effect, 3 DOFs model including two translation DOFs and one rotational DOF were introduced. The restoration forces of the collision system were considered as nonlinear springs. The equations of motion were derived if form of differential equations and numerically solved by 4th order Runge-Kutta method. The accuracy and the feasibility of this model were verified by the numerical example with parameter of moment arm length.

• Wind and Structures
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• 제11권5호
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• pp.391-411
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• 2008

A design procedure of stabilizing cable is proposed using buffeting analysis to stabilize the seesaw-like motion of the free cantilevered structure of a cable-stayed bridge during its construction. The bridge examined is a composite cable-stayed bridge having a main span length of 500 m. Based on the buffeting analysis, the stress in bare structure exceeded the allowable limit and a set of stabilizing cable was planned to mitigate the responses. The most efficient positions of the hold-down stabilizing cables were numerically investigated by means of an FE-based buffeting analysis and the required dimensions and pretension of the stabilizing cables were also calculated. The proposed stabilizing measure would be expected to secure the aerodynamic safety of a cantilevered structure under construction with considerable mitigation of buffeting responses.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.361-367
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• 2001

This research aims at evaluating the seismic performance of the R/C bridge piers, which were seismically designed in accordance with the seismic provision of limited ductile behavior of Eurocode 8. Pseudo dynamic test for six(6) circular RC bridge piers has been carried out so at to investigate their seismic performance subjected to experted artificial earthquake motions. The objective of this experimental study is to investigate the hysteretic behavior of reinforced concrete bridge piers. Important test parameters are confinement steel ratio, input ground motion, etc. The seismic behavior of circular concrete piers under artificial ground motions has been evaluated through displacement ductility, energy analysis, capacity spectrum. It can be concluded that RC bridge piers designed in the seismic code of limited ductile behavior of Eurocode 8 have been determined to show good seismic performance even under expected artificial earthquakes in moderate seismicity region.

• Structural Engineering and Mechanics
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• 제12권3호
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• pp.341-346
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• 2001

Near source earthquakes can be characterized not only by strong horizontal but also by strong vertical ground motions with broad range of dominant frequencies. The inelastic horizontal response of thin-walled L-shaped steel bridge piers, which are popularly used as highway bridge supports, subjected to simultaneous horizontal and vertical ground excitations of near source earthquakes is investigated. A comprehensive damage index and an evolutionary-degrading hysteretic model are applied. Numerical analysis reveals that the strong vertical excitation of a near source earthquake exerts considerable influences on the damage development and horizontal response of thin-walled L-shaped steel bridge piers.