튜브진동 시 지지부에서의 축ㆍ횡방향 미끄럼변위 분석

송주선(Ju-Sun Song),김형규(Hyung-Kyu Kim),이영호(Young-Ho Lee),김재훈(Jae-Hoon Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

Slip displacement is brought into focus to study the tube fretting wear that occurs on the contact by the springs. An oscillating tube was in contact with plate support springs. The contact condition was varied as normal force 5 N, and gaps of 0.1 and 0.2 ㎜ in the experiment. The oscillation range of the tube was also varied as 0.2, 0.3, 0.4 and 0.7 ㎜. Formulas for predicting the slip displacement range were derived in terms of the vibration amplitudes measured during the tube oscillation. It was found that the slip displacement in transverse direction was much higher (720~33000 times) than that in axial one. This resulted in the severer wear on the contact suffered from transverse slip.

The anchorage-slip effect on direct displacement-based design of R/C bridge piers for limiting material strains

P.E. Mergos 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.6

Direct displacement-based design (DDBD) represents an innovative philosophy for seismic design of structures. When structural considerations are more critical, DDBD design should be carried on the basis of limiting material strains since structural damage is always strain related. In this case, the outcome of DDBD is strongly influenced by the displacement demand of the structural element for the target limit strains. Experimental studies have shown that anchorage slip may contribute significantly to the total displacement capacity of R/C column elements. However, in the previous studies, anchorage slip effect is either ignored or lumped into flexural deformations by applying the equivalent strain penetration length. In the light of the above, an attempt is made in this paper to include explicitly anchorage slip effect in DDBD of R/C column elements. For this purpose, a new computer program named RCCOLA-DBD is developed for the DDBD of single R/C elements for limiting material strains. By applying this program, more than 300 parametric designs are conducted to investigate the influence of anchorage slip effect as well as of numerous other parameters on the seismic design of R/C members according to this methodology.

Three-dimensional simplified slope stability analysis by hybrid-type penalty method

Yamaguchi, Kiyomichi,Takeuchi, Norio,Hamasaki, Eisaku Techno-Press 2018 Geomechanics & engineering Vol.15 No.4

In this study, we propose a three-dimensional simplified slope stability analysis using a hybrid-type penalty method (HPM). In this method, a solid element obtained by the HPM is applied to a column that divides the slope into a lattice. Therefore, it can obtain a safety factor in the same way as simplified methods on the slip surface. Furthermore, it can obtain results (displacement and strain) that cannot be obtained by conventional limit equilibrium methods such as the Hovland method. The continuity condition of displacement between adjacent columns and between elements for each depth is considered to incorporate a penalty function and the relative displacement. For a slip surface between the bottom surface and the boundary condition to express the slip of slope, we introduce a penalty function based on the Mohr-Coulomb failure criterion. To compute the state of the slip surface, an r-min method is used in the load incremental method. Using the result of the simple three-dimensional slope stability analysis, we obtain a safety factor that is the same as the conventional method. Furthermore, the movement of the slope was calculated quantitatively and qualitatively because the displacement and strain of each element are obtained.

튜브 프레팅마멸 연구를 위한 접촉부 미끄럼 거동의 실험적 분석

송주선(Ju-Sun Song),김형규(Hyung-Kyu Kim),이영호(Young-Ho Lee),김재훈(Jae-Hoon Kim) 한국트라이볼로지학회 2004 한국트라이볼로지학회 학술대회 Vol.38 No.-

To study the fretting wear problem of a nuclear fuel, the behaviour of slip displacement at the contact is investigated in this paper. The slip displacement was evaluated from the vibration amplitudes measured during a fretting wear experiment in real time basis. The experiment was conducted in air at room temperature and one span of a fuel assembly was simulated. The contact condition between the grids and rods varied as the normal force of 5 N and gap of 0.2 ㎜. The fuel rod was vibrated with the frequency of 30 ㎐ and the center oscillation of 0.7 ㎜. Simple geometrical equations were used for the axial and transverse slip displacement. The trace of rod movement was investigated, which was affected by the contact condition. The vibration characteristic was not altered during the experiment when a specific contact condition was applied. The severest wear on the rod occurred in the case of axial slip and gap existence. It implies that the mechanism of impact wear should be understood for studying the fuel fretting problem.

철근 콘크리트 연결보의 하중 전달 기구와 변형 능력

홍성걸,장상기 한국지진공학회 2006 한국지진공학회논문집 Vol.10 No.3

콘크리트 부재의 내진설계에 있어 강도와 더불어 변형 능력은 중요한 요소이다. 연결보는 전단 지배 부재임에도 항복 이후 소성 변형을 요구하는 부재인데 본 연구에서는 연결보의 변형 능력에 대한 실험을 통해 변형 모형을 제시하였다. 일반적인 배근 형태를 가진 철근 콘크리트 연결보를 대상으로 단조하중실험을 수행하였다. 경간-깊이비, 휨 철근비, 전단 철근비를 변수로 하여 연결보의 거동을 평가하였다. 전단 지배 부재인 연결보는 아치작용과 트러스 작용으로 전단력에 대해 저항하는데 실험 결과를 통해 전단력을 두 작용의 구분과 항복 강도 발현 이후 소성 변형에 따른 두 작용의 구성비 변화에 대해 분석하였다. 실험결과에 기초한 전단 철근과 휨 철근의 변형률 분포 모형을 이용하여 휨 철근의 응력 상태를 산정하였다. 휨 철근의 부착-미끄러짐에 의해 결정되는 균열폭을 고려하는 연결보의 변형 모형을 제시하였다. 항복 상태는 휨 철근의 항복 시점으로 정의하였고, 극한 상태는 변형 증가에 따른 스트럿의 압축 강도 저하에 의해 결정되었다. 이 변형 모형은 변위기초설계에 활용될 수 있을 것으로 기대된다. An experimental investigation on the behavior of reinforced concrete coupling beams is presented. The test variables are the span-to-depth ratio, the ratio of flexural reinforcements and the ratio of shear rebars. The distribution of arch action and truss action which compose the mechanism of shear resistance is discussed. The increase of plastic deformation after yielding transforms the shear transfer by arch action into by truss action. This study proposes the deformation model for reinforced concrete coupling beams considering the bond slip of flexural reinforcement. The strain distribution model of shear reinforcements and flexural reinforcements based on test results is presented. The yielding of flexural reinforcements determines yielding states and the ultimate states of reinforced concrete coupling beam are defined as the ultimate compressive strain of struts and the degradation of compressive strength due to principal tensile strain of struts. The flexural-shear failure mechanism determines the ultimate state of RC coupling beams. It is expected that this model can be applied to displacement-based design methods.

Deep Displacement of Huangtupo Landslide in Three Gorges Reservoir Area, China

( Sha Lu ),( Huiming Tang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Huangtupo landslide, one of the biggest and most complicated landslides in the Three Gorges Reservoir area, is located in the old site of Badong county. The deformation and stability condition are closely related to human lives and properties. Field investigation and monitoring methods are adopted in revealing the spatial distribution and deformation conditions of slip zone. The results show that there are two slip zones in the upper and lower part of Sub-landsldie#1. The major lower slip zone is located at the eastern part of Sub-landsldie#1. The cumulative displacement at the front of No.1 Sub-landslide is between 157.23mm and 199.09mm. The value in the middle part of No.1 Sub-landslide is 256.78mm and 184.7mm from two monitoring site. At the edge of No.1 Sub-landslide, the cumulative displacement is 72.51mm. Multi-fractal dimension was adopted to reveal the shallow deformation evolution characteristics of No.1 Sub-landslide. The multi-fractal dimension values are relatively big and the affects a lot by rainfall and water level but the landslide is in a relatively stable condition. In the study of deep formation of Huangtupo landslide, in No.1 Sub-landslide, the cumulative displacement at the slip zone increase steadily from 0mm to 54.32mm. The maximum value of monthly deformation rate of the slip zone decrease from the front to the edge of No.1 Sub-landslide. The multi-fractal dimension of the deep displacement shows similar trend with that of shallow part of No.1 Sub-landslide.

Constant slip rate during the late Quaternary along the Sulu He segment of the Altyn Tagh Fault near Changma, Gansu, China

Seong, Yeong Bae,Kang, Hee Cheol,Ree, Jin‐,Han,Yi, Chaolu,Yoon, Hyeon Blackwell Publishing Asia 2011 The island arc Vol.20 No.1

<P><B>Abstract</B></P><P>The question of whether millennial‐scale geological slip rates are consistent with decade‐scale geodetic slip rates is of great importance in evaluating the nature of continental deformation within the Tibetan Plateau. We determined the time‐averaged slip rate of the Sulu He segment of the Altyn Tagh Fault, near Changma in Gansu Province, China, based on geomorphic analysis, remote sensing data, and cosmogenic <SUP>10</SUP>Be surface‐exposure age dating. Quaternary alluvial fan deposits in the study area (Qf1, Qf2, Qf3) are displaced by left‐lateral movement along the Altyn Tagh Fault. Because of the large accumulated displacement of these fans, some of them have become disconnected from the fan apexes that are directly linked to the debris‐source areas in the piedmont of the Qilian Shan to the south. The total minimum offsets are estimated to be about 429 ± 41 m for Qf1, about 130 ± 10 m for Qf2, and 32 ± 1 m for Qf3. The <SUP>10</SUP>Be surface‐exposure ages obtained for Qf1 and Qf2 are 100–112 ka and 31–43 ka, respectively. Accordingly, the slip rate since the period of Qf1 and Qf2 depositions is calculated to have been about 3.7 mm/yr.</P>

Characteristic of slipping behaviour in vibratory wear of a supported tube

Kim, Hyung-Kyu,Lee, Young-Ho Elsevier 2005 Wear: An international journal on the science and Vol.259 No.1

<P><B>Abstract</B></P><P>Fretting wear of a vibratory tube is studied from the investigation of the slipping characteristics on the contacts between the tubes and the supports. The primary application of the present research is the tube bundle structures subjected to a flow-induced vibration in the nuclear power plant components. Tests were carried out to simulate the vibration of the fuel rods, in particular, those supported by springs and dimples. Two typical types of supports were used at both ends of the tube, which was forced to vibrate with 30Hz. The supporting condition was varied artificially: positive contact force or gap existence. During the tube vibration, the amplitudes were measured continuously in the vicinity of the supports. Simple equations were derived to evaluate the slip displacement on the contacts. Wear volume, area and the maximum depth of the wear scars on the tubes were investigated after 10<SUP>6</SUP> vibration cycles. As a result, it was found that the supporting condition affected the vibration characteristics near the contacts. In the positive contact condition, the phase difference of the vibration signals at both sides of the contact was 180°. It is altered in the gap condition and the multiple values of 30Hz were found from the fast Fourier transform analysis. The high frequency vibration is thought to cause the wear to become severer in the gap condition. The support with dimples revealed more wear. The influence of the contact shape on the wear was discussed from this. The relationship between the slip displacement and the wear was also discussed together with a new wear parameter.</P>

전단지배 중량콘크리트 전단벽의 횡변위에 대한 전단 및 미끄러짐 변위 영향

황용하(Hwang, Yong-Ha),양근혁(Yang, Keun-Hyeok) 대한건축학회 2016 대한건축학회 학술발표대회 논문집 Vol.36 No.2

튜브진동 시 판스프링 지지부의 미끄럼변위와 마멸 분석

김형규(Hyung-Kyu Kim),이영호(Young-Ho Lee),송주선(Ju-Sun Song) 한국트라이볼로지학회 2003 한국트라이볼로지학회 학술대회 Vol.37 No.-

Tube oscillation behaviour is experimentally investigated for the study on the fuel rod fretting that is caused by the flow-induced vibration in nuclear reactor. The experiment was conducted in air at room temperature. The specimen of tube assembly was supported by plate springs which simulated the spacer grids and fuel rods of a fuel assembly. To investigate the influence of contact condition between the grids and rods, normal load of 10 and 5 N, gaps of 0.1 and 0.3 ㎜ were applied. The range of the oscillation at the center of the fuel rod specimen was varied as 0.2, 0.3 and 0.4 ㎜ to simulate the fuel rod vibration due to flow. Displacements near the contact were measured with four displacement sensors during the tube oscillation. As results, the shape of oscillation (phase) varied depending on the contact condition. The oscillation displacement increased considerably from the contact to gap condition. The displacement increased further as the gap size increased. It is regarded that the spring shape influences the tube oscillation behaviour. Simple calculation showed that the slip displacement was very small. Therefore, cumulative damage concept is necessary for the fuel rod wear. The mechanism of plowing is thought required to explain the severe wear in the case of gap existence.