• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 가을 학술발표회 논문집
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• pp.156-161
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• 1992

Over the past twenty years, the concept of structural control has been investigated for the application to large civil engineering structures. At the early years, passive control systems, such as tuned mass damper(TMD) and tuned liquid mass bamper(TLD), have been utilized to reduce the wind induced vibrations of tall buildings, decks and pylons of long-span bridges. More recently, the active control concept has been applied to reducing the structural vibration and increasing the human comfortness in tall buildings during strong wind. In this study, the effectiveness of the active tuned mass damper(ATMD) has been investigated for reducing vibration of large structures during strong earthquake. Stochastic optimal control theory has been employed. Example analyses are carried out through analytical simulation studies.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.8-9
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• 2020

While non-uniform shapes are appearing as an apparent building style recently, most architects predominantly think structure and construction technology should support the designed shape of non-uniform structures determined by the architect. Within such a governance structure of architect's perception, the role of an engineer is emphasized for technical support only. Especially, in making a decision on a structural design and plan, if various and objective reviews are not conducted, the design is very likely to be left only as a drawing even if the design is appropriate for criteria and norms. With the recognition of such problems, the present study attempted to propose an equal cooperative relationship between architects and engineers in designing non-uniform structures in the future.

• 대한토목학회논문집
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• 제29권2A호
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• pp.131-143
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• 2009

지진하중과 같은 횡하중에 대하여 교량구조물의 아칭작용은 교대 사이의 상부구조에 의해 발생하며 이를 상부구조의 저항능력이라고도 한다. 교량구조물의 아칭작용의 크기는 경간의 수에 영향을 받으며 또한 상부구조, 교대와 교각의 연결조건 및 상부구조와 하부구조의 강성비에도 영향을 받는다. 프리캐스트 콘크리트 상자형 교량의 비탄성 지진응답에 대한 아칭작용의 영향을 분석하기 위하여 경간수에 따른 두 가지 종류의 예제교량(교량 SB와 교량 LB), 교각의 높이의 배열에 따른 세가지 종류(대칭, 비대칭)의 교량, 상부구조와 하부구조의 연결조건에 따른 세가지 교량(형식 A, B, C)등에 대한 구분을 조합하여 18가지 종류의 예제구조물을 작성하였으며, 이 예제구조물들에 대하여 역량스펙트럼해석, 비탄성 시간이력해석을 수행하여 지진응답을 비교하여 아칭작용의 영향을 분석하였다. 아칭작용의 영향(최대변위의 감소와 저항능력의 증가)은 교량 SB(short bridge)의 경우가 교량 LB(long bridge) 보다 크게 나타났으며 대칭교량의 경우가 비대칭교량에 비하여 크게 나타남을 알수 있었다.

• International Journal of Concrete Structures and Materials
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• 제7권1호
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• pp.71-78
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• 2013

Prestressed concrete (PC) is the predominant material in highway bridge construction. The use of high-strength concrete has gained wide acceptance in the PC industry. The main target in the highway industry is to increase the durability and the life-span of bridges. Cracking of elements is one aspect which affects durability. Recently, nine 7.62 meter long PC I-beams made with different concrete strength were designed according to a simple, semi-empirical equation developed at the University of Houston (UH) (Laskar et al., ACI Journal 107(3): 330-339, 2010). The UH Method is a function of shear span-to-depth ratio (a/d), concrete strength $\sqrt{f^{\prime}_c}$, web area $b_wd$, and amount of transverse steel. Based on testing these girders, the shear cracking strength of girders with different concrete strength and different shear span-to-depth ratio was investigated and compared to the available approaches in current codes such as ACI 318-11 (2011) and AASHTO LRFD Specifications (2010).

• Wind and Structures
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• 제23권6호
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• pp.595-613
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• 2016

Large amplitude oscillation of steepled main cables usually presents during construction of a long-span bridge. To study this phenomenon, six typical main cables with different cross sections during construction are investigated. Two main foci have been conducted. Firstly, aerodynamic coefficients of a main cable are obtained and compared through simulation and wind tunnel test: (1) to ensure the simulation accuracy, influences of the numerical model's grid size, and the jaggy edges of main cable's cross section on main cable's aerodynamic coefficients are investigated; (2) aerodynamic coefficients of main cables at different wind attack angles are obtained based on the wind tunnel test in which the experimental model is made by rigid plastic using the 3D Printing Technology; (3) then numerical results are compared with wind tunnel test results, and they are in good agreement. Secondly, aerodynamic coefficients of the six main cables at different wind attack angles are obtained through numerical simulation. Then Den Hartog criterion is used to analyze the transverse galloping of main cables during construction. Results show all the six main cables may undergo galloping, which may be an important reason for the large amplitude oscillation of steepled main cables during construction. The flow structures around the main cables indicate that the characteristic of the airflow trajectory over a steepled main cable may play an important role in the galloping generation. Engineers should take some effective measures to control this harmful phenomenon due to the big possibility of the onset of galloping during the construction period.

• Wind and Structures
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• 제24권5호
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• pp.405-430
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• 2017

The aerodynamic characteristics of vehicles are critical to assess vehicle safety and passenger comfort for vehicles running on long span bridges in a windy environment. However, in previous wind-vehicle-bridge (WVB) system analysis, the aerodynamic interference between the vehicle and the bridge was seldom considered, which will result in changing aerodynamic coefficients. In this study, the aerodynamic coefficients of a high-sided truck on the ground (ground case) and a typical bridge deck (bridge deck case) are determined in a wind tunnel. The effects of existent structures including the bridge deck and bridge accessories on the high-sided vehicle's aerodynamic characteristics are investigated. A three-dimensional analytical framework of a fully coupled WVB system is then established based on the finite element method. By inputting the aerodynamic coefficients of both cases into the WVB system separately, the vehicle safety and passenger comfort are assessed, and the critical accidental wind speed for the truck on the bridge in a windy environment is derived. The differences in the bridge response between the windward case and the leeward case are also compared. The results show that the bridge deck and the accessories play a positive role in ensuring vehicle safety and improving passenger comfort, and the influence of aerodynamic interference on the response of the bridge is weak.

• Journal of the Korean Wood Science and Technology
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• 제37권4호
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• pp.300-309
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• 2009

목재를 이용한 구조의 효율적인 사용은 자원의 낭비를 줄이고 세계 환경을 보호할 수 있다. 이 연구는 대단면 목조건축을 위해 강재와 구조용 집성재를 이용한 내화성능을 지닌 복합재료의 개발을 목적으로 한다. 내화 시험에 앞서 구조용 강재와 구조용 집성재를 이용한 복합재료의 휨강도 특성을 확인하고자 한다. 구조용 강재 보(H type)와 구조용 집성재 보, 구조용 강재와 구조용 집성재를 이용한 복합재료 보의 휨시험을 시행하였다. 구조용 집성재간의 접착제로는 레졸시놀계를 사용하였으며 구조용 강재와 구조용 집성재 간의 접착제로는 폴리우레탄 수지를 사용하였다. 휨시험은 KS F 2150에 의거하여 시행하였으며 각각의 평균 최대하중은 복합재료가 137.5 kN, 구조용 집성재가 106.5 kN, 구조용 강재가 48 kN을 나타내었다. 구조용 집성재가 높은 휨탄성력을 지니고 있기 때문에 복합재료를 사용할 경우 구조적 안정성을 부여할 뿐 아니라 친환경적인 재료로 이용될 수 있을 것이다.

• 한국공간구조학회논문집
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• 제9권1호
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• pp.79-85
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• 2009

최근의 대공간구조물은 장스팬화 됨은 물론이고 경량화되면서 면외 방향의 강성이 매우 작아지고 있다. 이로 인하여 공력불안정 진동의 발생 여부는 물론이고 연성구조물의 판단시에도 고유진동수의 정확한 산정이 필요하다. 그러나 국내외 대공간구조물의 고유진동수 제안식에 대한 연구는 매우 미흡한 실정이다. 따라서 국내 7개 공간구조물의 고유치해석에서 얻은 근사식을 일본건축학회 고유치해석에 근거한 2가지 제안식과 일본의 28개 공간구조물의 계측치에서 얻은 고유진동수 근사식을 비교하였다. 지붕의 고유진동수는 스팬이 증가함에 따라서 작아지는 경향을 확인하였다. 국내의 고유진동수 값은 전반적으로 일본의 공간구조물의 해석과 계측에 근거한 고유진동수보다 동일한 스팬에서 작은 경향을 보임을 알 수 있었다. 따라서 국내 공간구조물의 지붕은 일본의 경우보다 비교적 연성구조물인 것을 확인할 수 있다.

• Earthquakes and Structures
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• 제26권5호
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• pp.401-416
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• 2024

Long-span structures, such as bridges, can experience different seismic excitations at the supports due to spatially variability of ground motion. Regarding current bridge designing codes, it is just EC 2008 that suggested some regulations to consider it and in the other codes almost ignored while based on some previous studies it is found that the effect of mentioned issue could not be neglected. The current study aimed to perform a comprehensive study about the effect of spatially varying ground motions on the dynamic response of a reinforced concrete bridge under asynchronous input motions considering soil-structure interactions. The correlated ground motions were generated by an introduced method that contains all spatially varying components, and imposed on the supports of the finite element model under different load scenarios. Then the obtained results from uniform and non-uniform excitations were compared to each other. In addition, the effect of soil-structure interactions involved and the corresponding results compared to the previous results. Also, to better understand the seismic response of the bridge, the responses caused by pseudo-static components decompose from the total response. Finally, an incremental dynamic analysis was performed to survey the non-linear behavior of the bridge under assumed load scenarios. The outcomes revealed that the local site condition plays an important role and strongly amplifies the responses. Furthermore, it was found that a combination of wave-passage and strong incoherency severely affected the responses of the structure. Moreover, it has been found that the pseudo-static component's contribution increase with increasing incoherent parameters. In addition, regarding the soil condition was considered for the studied bridge, it was found that a combination of spatially varying ground motions and soil-structure interactions effects could make a very destructive scenarios like, pounding and unseating.

• 한국지진공학회논문집
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• 제11권3호
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• pp.53-62
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• 2007

이 연구에서는 작용하는 하중특성에 따라 적절한 감쇠력을 발휘할 수 있는 복합감쇠기(complex damper)를 제안하고 그 유용성을 장대교량의 지진응답해석을 통하여 검토하였다. 제안한 복합감쇠기는 두개 이상의 탄소성감쇠기(elasto-plastic damper)와 오일 감쇠기(oil damper)의 조합에 의하여 구성되며, 탄소성감쇠기의 변위의존적인 특성과 오일감쇠기의 속도의존적인 특성을 적절히 결합함으로서 효율적인 감쇠시스템의 구성이 가능하게 하였다. 중소형의 지진이나 작은 진폭의 진동에서는 오일감쇠기가 주로 진동을 흡수하며, 발생 빈도가 낮으나 규모가 큰 지진 등에 대해서는 탄소성 감쇠기가 진동에너지를 흡수한다. 이와 같이 복합감쇠기는 두 가지 종류의 감쇠기 역할을 잘 구분시켜 경제적이고 제진효율성이 뛰어난 설계를 가능하게 한다. 복합감쇠장치의 수학적 모델을 정립하였고, 수치모사를 통하여 응답특성과 효율성을 평가하였다. 수치모사 결과, 복합감쇠기는 단일의 수동형감쇠기를 이용하는 경우보다 뛰어난 감쇠효과를 더욱 경제적으로 구현할 수 있으며 내진성능을 크게 향상시킬 수 있는 것으로 나타났다.