• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.448-454
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• 2000

Piled multi-block system has been frequently adopted in the historic structures or monuments of cultural heritage. It is well known that such a structural system is very vulnerable to the earthquake shaking. If the structure is of slender type, then it may experience overturning at very low level intensity of ground shaking. One of the methods used to protect such structures from earthquake is seismic isolation system. But the behavior of multi-block systems mounted on the isolated basis is not well understood yet. In this paper we investigate the dynamic behavior of single slender rigid block mounted on the three different isolation systems, i.e., P-F system, FPS and LRB system. Sliding at the isolation interface of P-F system and FPS is formulated based on Coulomb friction. The mounted single block is assumed undergoing rocking or sticking only. Impacting of a single block is described using distinct element method (DEM). Free vibrations due to a prescribed initial conditions are studied. Responses to the harmonic excitation and earthquake motions are calculated

• Structural Engineering and Mechanics
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• 제30권1호
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• pp.99-117
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• 2008

This paper presents a comprehensive approach to the evaluation of macroscopic material parameters for natural stone and quarry masonry. To that end, a reliable non-linear material model on a meso-scale is developed to cover the random arrangement of stone blocks and quasi-brittle behaviour of both basic components, as well as the impaired cohesion and tensile strength on the interface between the blocks and mortar joints. The paper thus interrelates the following three problems: (i) definition of a suitable periodic unit cell (PUC) representing a particular masonry structure; (ii) derivation of material parameters of individual constituents either experimentally or running a mixed numerical-experimental problem; (iii) assessment of the macroscopic material parameters including the tensile and compressive strengths and fracture energy.

• 한국공간구조학회논문집
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• 제8권3호
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• pp.83-90
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• 2008

우리나라의 석조문화재를 모델링할 때 불연속면을 갖는 구조재의 강성을 어떻게 규명하느냐가 매우 중요하지만 원형보존을 해야 하는 문화재의 특성상 이를 파악하기란 매우 곤란하다. 이를 위해 본 연구에서는 비파괴조사를 이용하여 고유진동수를 측정한 후, 시행착오법을 이용하여 측정된 고유진동수와 컴퓨터 모델링 결과 파악된 고유진동수를 비교함으로써 불연속면의 강성, 구조재의 탄성계수 등 홍예교를 이루는 재료의 구조적 물성을 추정함으로써 컴퓨터 모델링을 하는 방법을 제시하고 홍예교량의 동적특성에 영향을 미치는 요인을 분석하였다. 연구결과 무사석 및 적심석의 강성이 홍예교의 동적특성에 가장 큰 영향을 미치는 것으로 분석되었다.

• 한국공간구조학회논문집
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• 제18권1호
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• pp.45-53
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• 2018

Following the earthquake that shook the city of Gyeongju, Korea, in 2016, it became apparent that research on the safety of cultural heritages against the seismic hazards is necessary in Korea. Predictions of how historically significant stone pagodas would behave the earthquakes anticipated in near future, which are the subject of this study, is also required. In this study, the dynamic characteristics of 15 cultural heritage designated stone pagodas of Korea were investigated, including natural frequency and damping ratio, and the stiffness of the stone material and its contact area were determined using eigenvalue analysis by assuming the stone pagodas to be multi-degree-of-freedom structures. The results of this study enable the structural modeling of stone pagodas using a finite element analysis program and the method is expected to be useful in assessing the structural safety of stone pagodas against vertical loads as well as lateral forces, including earthquakes. Also, by identifying the dynamic characteristics of the structures, the results of this study can be utilized as a nondestructive testing method to determine the rigidity of cultural heritage structures and to identify inherent problems. The natural frequencies of the Korean stone pagodas were measured to be within 3.5~8.3Hz, excluding cases with distinct natural frequency results, and it was determined that the natural frequencies of the stone pagodas are influenced by various parameters including the height and joint stiffness of the structures.

• 콘크리트학회논문집
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• 제14권5호
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• pp.718-725
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• 2002

본 연구에서는 R/C 골조구조물에 대한 내진성능개선 방법으로서, 벽식 마찰 감쇄기 모델을 새롭게 제안하였다. 기존의 감쇄 장치가 일반적으로 브레이스 부재 형태를 취하고 있으나, 브레이스형 감쇄장치는 시공상 강골조구조물에는 적용하기 용이한 반면 R/C 골조구조물에 적용 시에는 R/C 구조부재와 감쇄기간의 연결 문제, 감쇄기와 R/C 부재 연결부에서의 응력집중으로 인한 R/C 구조부재의 파손 우려 등의 단점이 있다. 제안된 감쇄기는 감쇄기 연결부의 R/C 구조부재 파손 및 구조물의 P-Δ효과를 줄이는데 장점을 가지면서 감쇄기로서의 역할을 발휘하도록 한 테프론 슬라이더와 R/C 전단벽 조합형 감쇄기이다. 제안된 감쇄기의 내진성능개선 능력을 평가하기 위하여, 감쇄기의 수치모델을 고려한 R/C 골조구조물의 비선형 동적해석 알고리즘을 제시하였다. 지진하중이 작용하는 기존의 10층 3경간 R/C 골조구조물에 본 감쇄기를 적용한 수치해석 결과, 시간이력거동 및 층간변위의 억제에서 탁월한 제어효과를 나타내었으며, 저층 기둥 부재의 소성힌지 발생 및 구조부재의 손상을 감쇄기의 소산에너지로 억제하여 줌으로서 구조물 내진성능개선에 효과가 우수한 것으로 평가되었다.

• Wind and Structures
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• 제14권3호
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• pp.221-238
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• 2011

The estimated response of large-scale engineering structures to severe wind loads is prone to modelling uncertainties that can only ultimately be assessed by full-scale testing. To this end ambient vibration data from full-scale monitoring of the historic Clifton Suspension Bridge has been analysed using a combination of a frequency domain system identification method and a more elaborate stochastic identification technique. There is evidence of incipient coupling action between the first vertical and torsional modes in strong winds, providing unique full-scale data and making this an interesting case study. Flutter derivative estimation, which has rarely previously been attempted on full-scale data, was performed to provide deeper insight into the bridge aerodynamic behaviour, identifying trends towards flutter at higher wind speeds. It is shown that, as for other early suspension bridges with bluff cross-sections, single-degree-of-freedom flutter could potentially occur at wind speeds somewhat below requirements for modern designs. The analysis also demonstrates the viability of system identification techniques for extracting valuable results from full-scale data.

• 지구물리
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• 제6권2호
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• pp.71-77
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• 2003

Generally the dynamic characteristics of stone wall structures depend on several factors such as contact, the type of interlocking bonding stones, and the filling materials. This paper describes a non-destructive technique for diagnosis of historic masonry stone structures using the measurement of natural frequency technique. For this purpose, the castle wall of Nag-An Folk Town located in Sunchon, Korea was selected as a model. The Nag-An Town Castle is one of the well maintained historical remains constructed in the Chosun Kingdom of Korea. The construction started in 1397 A.D and was finished in 1626 A.D. The non-mortar castle wall is 1470m long and the average height is 4m with a width of 3 4m. The exterior of the wall is bonded with 1 2 m rectangular rough-faced stone and the inside of the wall is filled with gravel. The traditional village still remains inside the Nag-An Town Castle, and they have a regional food festival every October. Transverse vibrations were measured at 8 points around the castle. The measured natural frequency of the first mode was 26Hz 41Hz, and the shear modulus of filling material was 2.142 x $10^3$ ~ 8.915 x $10^3$kgf/$cm^2$ . With these results, it may be assumed that the filling material is gravel or a sand-gravel mixture. It is expected that the information provided by this paper will be useful for addressing the maintenance problems of the old castle walls.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.595-618
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• 2010

This paper describes the application of a wireless sensor network to a 31 meter-tall medieval tower located in the city of Trento, Italy. The effort is motivated by preservation of the integrity of a set of frescoes decorating the room on the second floor, representing one of most important International Gothic artworks in Europe. The specific application demanded development of customized hardware and software. The wireless module selected as the core platform allows reliable wireless communication at low cost with a long service life. Sensors include accelerometers, deformation gauges, and thermometers. A multi-hop data collection protocol was applied in the software to improve the system's flexibility and scalability. The system has been operating since September 2008, and in recent months the data loss ratio was estimated as less than 0.01%. The data acquired so far are in agreement with the prediction resulting a priori from the 3-dimensional FEM. Based on these data a Bayesian updating procedure is employed to real-time estimate the probability of abnormal condition states. This first period of operation demonstrated the stability and reliability of the system, and its ability to recognize any possible occurrence of abnormal conditions that could jeopardize the integrity of the frescos.

• 한국농촌건축학회논문집
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• 제26권2호
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• pp.35-40
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• 2024

This study examines the classification and typical characteristics of 148 owner shop houses existing in the historical city center of Cheongju. First, they can be classified into single-story, middle-story, and divided types according to the distribution of residential and commercial functions. The single-story(36) has 'ㅡ', 'ㄱ', and 'narrow and deep'-shaped arrangement, with stores on the front and houses on the rear. The middle-story second floor(89) is divided into a first-story store and a second-story house, and the third floor(23) has different functions for each floor, but more than half of them have houses on the second and third floors. Among the total, there are also 16 cases in which the division type is taken with different construction times and structures. Second, in the position of the stairs connected to the upper floor among the middle-floor types(112), the outer stair type(52) to separate from the living space while making the most of the stores on the first floor accounts for 47%, but the biggest feature is that the inner staircase type(34) with privacy reaches 30%. The rear stair room type(26) entering through alleyways or private yards is also 23%. Third, the front pillar spacing varies from 1bay to 4bay in appearance, but the 2bay type on the 2nd floor and the 1bay type on the 3rd floor occupy the largest proportion. This exterior type is a characteristic of a owner shop house that can measure the range of personal ownership. Despite the conflicting functions of stores and houses, 35~40% of the cases are in which the opening positions of the upper and lower floors are unified.

• 한국공간구조학회논문집
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• 제11권4호
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• pp.61-69
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• 2011

우리나라의 석조문화재을 모델링할 때 불연속면을 갖는 구조재의 강성을 어떻게 규명하느냐가 매우 중요하지만 원형보존을 해야 하는 문화재의 특성상 이를 파악하기란 매우 곤란하다. 이를 위해 본 연구에서는 비파괴조사를 이용하여 고유진동수를 측정한 후, 시행착오법을 이용하여 측정된 고유진동수와 컴퓨터 모델링 해석을 통해 고유진동수를 비교함으로써 불연속면의 강성, 구조재의 탄성계수 등 숭례문 육축 구조를 이루는 재료의 구조적 물성을 추정하였다. 이를 통해 육축 문화재에 대한 컴퓨터 모델링 기법을 제시하고 육축구조물의 안전성에 영향을 미치는 요인을 분석하였다. 연구결과 적심석의 강성이 육축구조물의 안전성에 가장 큰 영향을 미지는 젓으로 분석되었다.