• Smart Structures and Systems
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• 제20권6호
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• pp.641-656
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• 2017

The effects of vertical component of earthquakes on torsional amplification due to mass eccentricity in seismic responses of base-isolated structures subjected to near-field ground motions are studied in this paper. 3-, 6- and 9-story superstructures and aspect ratios of 1, 2 and 3 have been modeled as steel special moment frames mounted on Triple Concave Friction Pendulum (TCFP) bearings considering different period and damping ratios. Three-dimensional linear superstructures resting on nonlinear isolators are subjected to both 2 and 3 component near-field ground motions. Effects of mass eccentricity and vertical component of 25 near-field earthquakes on the seismic responses including maximum isolator displacement and base shear as well as peak superstructure acceleration are studied. The results indicate that the effect of vertical component on the responses of asymmetric structures, especially on the base shear is significant. Therefore, it can be claimed that in the absence of the vertical component, mass eccentricity has a little effect on the base shear increase. Additionally, the impact of this component on acceleration is remarkable so the roof acceleration of a nine-story structure has been increased 1.67 times, compared to the case that the structure is subjected to only horizontal components of earthquakes.

• Earthquakes and Structures
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• 제15권5호
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• pp.453-462
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• 2018

Damages to buildings affected by a near-fault strong ground motion are largely attributed to the vertical component of the earthquake resulting in column failures, which could lead to disproportionate building catastrophic collapse in a progressive fashion. Recently, considerable interests are awakening to study effects of earthquake vertical components on structural responses. In this study, detailed modeling and time-history analyses of a 12-story code-conforming reinforced concrete moment frame building carrying the gravity loads, and exposed to once only the horizontal component of, and second time simultaneously the horizontal and vertical components of an ensemble of far-field and near-field earthquakes are conducted. Structural responses inclusive of tension, compression and its fluctuations in columns, the ratio of shear demand to capacity in columns and peak mid-span moment demand in beams are compared with and without the presence of the vertical component of earthquake records. The influences of the existence of earthquake vertical component in both exterior and interior spans are separately studied. Thereafter, the correlation between the increase of demands induced by the vertical component of the earthquake and the ratio of a set of earthquake record characteristic parameters is investigated. It is shown that uplift initiation and the magnitude of tensile forces developed in corner columns are relatively more critical. Presence of vertical component of earthquake leads to a drop in minimum compressive force and initiation of tension in columns. The magnitude of this reduction in the most critical case is recorded on average 84% under near-fault ground motions. Besides, the presence of earthquake vertical components increases the shear capacity required in columns, which is at most 31%. In the best case, a direct correlation of 95% between the increase of the maximum compressive force and the ratio of vertical to horizontal 'effective peak acceleration (EPA)' is observed.

• 한국공간구조학회논문집
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• 제9권1호
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• pp.69-78
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• 2009

최근의 근단층지반운동인 Northridge 지진(1994, 미국), Kobe 지진(1995, 일본), Izmit 지진(1990, 터키)은 큰 수직성분의 영향으로 건축물 및 교량에 심각한 손상을 주었다. 일반적인 건축구조물의 내진설계에서 지진하중의 수직성분을 고려하여 설계하는 경우는 드물다. 본 연구에서는 지진하중의 수직성분 영향의 고려 유무에 따른 예제구조물의 기둥부재의 축력의 변화와 부재 단부의 소성힌지회전각을 산정하여 시스템의 손상상태를 평가하여 보았다. 해석결과 축력의 증가는 기둥부재의 손상에 의한 전체 구조시스템의 story collapse mechanism의 가능성을 주게 되므로 근단층지반운동이 예상되는 부분에서는 지진하중의 수직성분에 대한 영향을 고려하여야할 것으로 판단된다.

• Geomechanics and Engineering
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• 제29권2호
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• pp.133-143
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• 2022

The catastrophic earthquake-induced failure of slopes concentrically distributed at near-fault area, which indicated the special features of near-fault ground motions, i.e. horizontal pulse-like motion and large vertical component, should have great effect on these geo-disasters. We performed shaking table tests to investigate the effect of both horizontal pulse-like motion and vertical component on dynamic response of slope. Both unidirectional (i.e., horizontal or vertical motions) and bidirectional (i.e., horizontal and vertical components) motions are applied to soft rock slope model, and acceleration at different locations is reordered. The results show that the horizontal acceleration amplification factor (AAF) increases with height. Moreover, the horizontal AAF under unidirectional horizontal pulse-like excitations is larger than that subject to ordinary motion. The vertical AAF does not show an elevation amplification effect. The seismic response of slope under different bidirectional excitations is also different: (1) The horizontal AAF is roughly constant under horizontal pulse-like excitations with and without vertical waves, but (2) the horizontal AAF under ordinary bidirectional ground motions is larger than that under unidirectional ordinary motion. Above phenomena indicate that vertical component has limited effect on seismic response when the horizontal component is pulse-like ground motion, but it can greatly enhance seismic response of slope under ordinary horizontal motion. Moreover, the vertical AAF is enhanced by horizontal motion in both horizontal pulse-like and ordinary motion. Thence, we should pay enough attention to vertical ground motion, especially its horizontal component is ordinary ground motion.

• 수산해양기술연구
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• 제34권2호
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• pp.144-158
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• 1998

In order to study basic information on the developed electro-magnetic compass, experiments were carried out on board M. S. KAYA at the pier of Dong Kuk Steel Mill in Pusan and the Korean southern sea using a three-axis magnetic sensor from Jan. 21, 1995 to Feb. 14, 1996. The obtained results were as follows : 1. The amount of old metal on the pier was about 27,290tons~57,440tons with an average of 40,560tons, the artificial local disturbance at the pier was min. 27.1$\mu$T, max. 66.5$\mu$T, ave. 433$\mu$T for the horizontal component and min. -27.0$\mu$T, max. 45.1$\mu$T, ave. 3.7$\mu$T for the vertical component. Its direction of horizontal component was 305$^{\circ}$ with the ship's head up bearing at 225$^{\circ}$. 2. The ship's magnetic distribution on the starboard side on berthing at the pier was 17.4$\mu$T for the horizontal component and -6.2$\mu$T for the vertical component. On the ship's port side, it was 19.8$\mu$T for the horizontal component and 4.1$\mu$T for the vertical component. On the ship's starboard side at sea, the ship's magnetic distribution was 19.2$\mu$T for the horizontal component and 3.2$\mu$T for the vertical component. On the ship's port side, the readings were 22.0$\mu$T for the horizontal component and -1.8$\mu$T for the vertical component. The directions of these readings were nearly starboard side. 3. On the pier, the secular change of the artificial local disturbance decreased 8.3$\mu$T from 61.0$\mu$T to 52.7$\mu$T for the horizontal component and decreased 7.1$\mu$T from 8.9$\mu$T M 1.8$\mu$T for the vertical component. On the starboard side from its berth, the ship, s magnetic distribution increased 2.6$\mu$T from 14.8$\mu$T to 17.4$\mu$T for the horizontal component and increased -0.1$\mu$T from -6.1$\mu$T to -6.2$\mu$T for the vertical component. On the ship's port side from its berth, it increased 7.1$\mu$T from 12.7$\mu$T to 19.8$\mu$T for the horizontal component and increased 10.2$\mu$T from -6.1$\mu$T to 4.1$\mu$T for the vertical component. 4. While at sea, on the ship's starboard side, the Secular change of the ship's magnetic distribution increased 3.9$\mu$T from 15.3$\mu$T to 19.2$\mu$T for the horizontal component and increased 2.0$\mu$T from -5.2$\mu$T to -3.2$\mu$T for the vertical component. On the port side, the changes increased 11.4$\mu$T from 10.6$\mu$T to 22.0$\mu$T for the horizontal component and increased 4.9$\mu$T from -6.7$\mu$T to -1.8$\mu$T for the vertical component. Upon berthing at the pier, the deviation of the secular change increased westerly 1 degree W~ 2.5$^{\circ}$ W from 3.5$^{\circ}$ W~ 5$^{\circ}$ W M 6W with the ship's head up bearing at 225$^{\circ}$. While at sea, these increased westerly 2$^{\circ}$ ~ 3$^{\circ}$ from the Northeast to the South and increased easterly 1$^{\circ}$ ~ 8$^{\circ}$ from the Southwest to the North. 5. While at port, within 1 mile between the ship and berth of the pier, as we approached the pier, the westerly deviation increased and when we departed the pier easterly deviation increased. When approaching the pier, the deviation was smaller than the deviation when the ship was departing from the pier. When approaching the bearing at 225$^{\circ}$ with the ship's head up bearing, the varies of deviation was smaller than the varies when the ship's head up bearing was departing from it.

• Computers and Concrete
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• 제20권4호
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• pp.369-380
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• 2017

The effects of the vertical component of a ground motion on the earthquake performances of semi-ductile high-rise R/C structures were investigated in the present study. Linear and non-linear time-history analyses were conducted on an existing in-service R/C building for the loading scenarios including and excluding the vertical component of the ground motion. The ratio of the vertical peak acceleration to the horizontal peak acceleration (V/H) of the ground motion was adopted as the main parameter of the study. Three different near-source earthquake records with varying V/H ratio were used in the analyses. The linear time-history analyses indicated that the incorporation of the vertical component of a ground motion into analyses greatly influences the vertical deflections of a structure and the overturning moments at its base. The lateral deflections, the angles of rotation and the base shear forces were influenced to a lesser extent. Considering the key indicators of vertical deflection and overturning moments determined from the linear time-history analysis, the non-linear analyses revealed that the changes in the forces and deformations of the structure with the inclusion of the vertical ground motion are resisted by the shear-walls. The performances and damage states of the beams were not affected by the vertical ground motion. The vertical ground motion component of earthquakes is markedly concluded to be considered for design and damage estimation of the vertical load-bearing elements of the shear-walls and columns.

• Wind and Structures
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• 제38권4호
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• pp.245-259
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• 2024

In a tornadic wind field, the vertical velocity component in certain regions of tornadoes can be significant, forming one of the major differences between tornadic wind fields and synoptic straight-line wind fields. To better understand the wind characteristics of tornadoes and properly estimate the action of tornadoes on civil structures, it is important to ensure that all the attributes of tornadoes are captured. Although Doppler radars have been used to measure tornadic wind fields, they can only directly provide information on quasi-horizontal velocity. Therefore, lots of numerical simulations and experimental tests in previous research ignored the vertical velocity at the boundary. However, the influence of vertical velocity in tornadic wind fields is not evaluated. To address this research gap, this study is to use an approach to derive the vertical velocity component based on the horizontal velocities extracted from the radar-measured data by mass continuity. This approach will be illustrated by using the radar-measured data of Spencer Tornado as an example. The vertical velocity component is included in the initial inflow condition in the CFD simulation to assess the influence of including vertical velocity in the initial inflow condition on the entire tornadic wind field.

• 산업기술연구
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• 제36권
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• pp.65-69
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• 2016

Deflection of the vertical is used in geodetic surveying associated with geoid network construction for geoid modeling and ellipsoid decision and obtained by gravity survey, astronomic survey etc. Technique of astronomic survey and gravity survey is very complex and requires a significant amount of time until gathering data. So this study is to determined a various method which evaluates deflection of the vertical and components about deflection of the vertical using GPS results and orthometric height value decided by leveling. Results of components about deflection of the vertical using GPS/leveling is that ${\xi}$ conponent is distributed $-2.11^{{\prime}{\prime}}{\pm}0.62$, ${\eta}$ component is distributed $1.75^{{\prime}{\prime}}{\pm}0.71$. Decision of component about deflection of the vertical using GPS is less complex than existing astronomic survey. Decision of component about deflection of vertical line using GPS is not complicated than astronomic surveying and can determine in a very short time. So it will be important means to determine the exact orthometric height, topographic study and diastrophism if can periodically calculate.

• Earthquakes and Structures
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• 제23권2호
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• pp.169-181
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• 2022

To research the dynamic response of the high-rise structure under the rocking ground motion, which we believed that the effect cannot be ignored, especially accompanied by vertical ground motion. Theoretical analysis and shaking table seismic simulation tests were used to study the response of a high-rise structure to excitation of a H-V-R ground motion that included horizontal, vertical, and rocking components. The use of a wavelet analysis filtering technique to extract the rocking component from data for the primary horizontal component in the first part, based on the principle of horizontal pendulum seismogram and the use of a wavelet analysis filtering technique. The dynamic equation of motion for a high-rise structure under H-V-R ground motion was developed in the second part, with extra P-△ effect due to ground rocking displacement was included in the external load excitation terms of the equation of motion, and the influence of the vertical component on the high-rise structure P-△ effect was also included. Shaking table tests were performed for H-V-R ground motion using a scale model of a high-rise TV tower structure in the third part, while the results of the shaking table tests and theoretical calculation were compared in the last part, and the following conclusions were made. The results of the shaking table test were consistent with the theoretical calculation results, which verified the accuracy of the theoretical analysis. The rocking component of ground motion significantly increased the displacement of the structure and caused an asymmetric displacement of the structure. Thus, the seismic design of an engineering structure should consider the additional P-△ effect due to the rocking component. Moreover, introducing the vertical component caused the geometric stiffness of the structure to change with time, and the influence of the rocking component on the structure was amplified due to this effect.

• 지구물리와물리탐사
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• 제3권2호
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• pp.48-52
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• 2000

저주파수 전자탐사 관로 탐지기 개발 및 현장 운용시의 지침을 마련하기 위해 3차원 유한요소법을 이용해서 수평 자기 쌍극자 송신원에 의한 도전성 지하 매설 관로의 전자기 반응을 계산하고 그 특성을 분석하였다. 단일 관로의 전자기 반응은 수평 자기장 및 수직 자기장의 수평 차분치 모두 관로 직상부에서 최대값을 나타낸다. 반응 곡선에서 최대값의 1/2이 되는 위치의 폭은 수평 자기장의 경우 수직 자기장의 수평 차분치보다 2배 정도 넓으며, 이는 수직 자기장의 수평 차분치가 관로 위치 분해능이 높은 것을 의미한다. 그리고 관로의 심도 계산식이 관로의 직상부에서만 정의되기 때문에 분해능이 높은 수직 자기장의 수평 차분치를 측정하는 것이 관로 심도 결정시 유리할 것이다. 서로 2 m 떨어진 이중 관로의 전자기 반응은 수직 자기장의 수평 차분의 경우 송신기 하부 및 인접 관로의 상부 모두에서 반응 곡선의 피크가 보인다. 이에 반해 수평 자기장의 경우는 인접 관로에 의한 자기장은 송신기 하부 관로에 의한 자기장에 의해 상쇄되어 송신기 하부 관로에 의한 피크만 나온다. 이로 미루어 볼 때 지하에 다수의 관로가 인접하여 매설되어 있는 상황에서는 수직 자기장의 수평 차분을 측정함으로써 다수 관로의 탐지도 가능할 것으로 보인다. 그리고 반응 곡선의 폭을 비교할 때, 단일 관로에서와 마찬가지로 분해능은 수직 자기장의 수평 차분치를 측정하는 것이 수평 자기장을 측정하는 것에 비해 뛰어난 것으로 판단된다.