• 한국구조물진단유지관리공학회 논문집
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• 제22권1호
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• pp.56-63
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• 2018

이 연구에서는 연성중심의 보강을 위하여 벽체의 양단부에서 경계요소를 형성하는 내진 보강공법이 적용된 벽체의 반복 휨 거동을 평가하였다. 벽체 경계요소에서 구속효과를 위한 횡보강은 프리스트레스트 와이어로프를 사용하였다. 주요 변수는 제시된 단면 확대공법의 보강 높이로 하였다. 최소 보강 높이는 보강 벽체와 기존 벽체의 모멘트 분포의 비교로부터 결정하였다. 실험결과, 제시된 보강방법은 벽체의 휨 강성 및 연성향상에 매우 효율적이었는데, 최대내력 시 강성과 최대내력의 80%지점에서 산정한 일손상지수는 무보강 벽체에 비해 각각 평균 46%와 210% 증가하였다. 보강높이가 벽체의 일손상지수 증가에 미치는 영향은 보강높이가 $2.0l_w$ 이상일 때 중요하지 않았다. 보강된 벽체의 휨 내력은 ACI 318-14에서 제안하는 등가응력블록을 통한 예측 값보다 22% 이상 높았다.

• Structural Engineering and Mechanics
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• 제31권5호
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• pp.545-566
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• 2009

Bridge columns are subjected to combined actions of axial force, shear force and bending moment during earthquakes, caused by spatially-complex earthquake motions, features of structural configurations and the interaction between input and response characteristics. Combined actions can have significant effects on the force and deformation capacity of RC columns, resulting in unexpected large deformations and extensive damage that in turn influences the performance of bridges as vital components of transportation systems. This paper evaluates the seismic response of three prototype reinforced concrete bridges using comprehensive numerical models that are capable of simulating the complex soil-structural interaction effects and nonlinear behavior of columns. An analytical approach that can capture the shear-flexural interacting behavior is developed to model the realistic nonlinear behavior of RC columns, including the pinching behavior, strength deterioration and stiffness softening due to combined actions of shear force, axial force and bending moment. Seismic response analyses were conducted on the prototype bridges under suites of ground motions. Response quantities of bridges (e.g., drift, acceleration, section force and section moment etc.) are compared and evaluated to identify the effects of vertical motion, structural characteristics and the shear-flexural interaction on seismic demand of bridges.

• Geomechanics and Engineering
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• 제24권1호
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• pp.67-79
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• 2021

The influence of ground motions on the seismic response of utility tunnels was investigated. A series of small-scale shaking table model tests were carried out under uniform excitation in the transverse direction. Different peak accelerations of EL-Centro and Taft earthquake waves were applied. The acceleration responses, earth pressure, seismic strain, bending moment and structure deformations were measured and discussed. The results showed that the types of earthquake waves had significant influences on the soil-structure acceleration responses. However, the amplitude of the soil acceleration along the depth showed consistent variation regardless of the types of earthquake waves and tunnels. The horizontal soil pressure near the top and bottom slabs showed obviously larger values than those at other depths. In general, the strain response in the outer surface was more significant than that on the inner surface, and the peak strain in the end section of the model was larger than that in the middle section. Moreover, the bending moment at the corner points was much larger than that at middle point, and the bending moment was greatly affected by both input accelerations and seismic wave types. The opposite direction of shear deformation on the top and bottom slabs presented a rotation trend of the model structure.

• 한국공간구조학회논문집
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• 제22권2호
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• pp.29-37
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• 2022

The collapse of reinforced concrete (RC) frame buildings is mainly caused by the failure of columns. To prevent brittle failure of RC column, numerous studies have been conducted on the seismic performance of strengthened RC columns. Concrete jacketing method, which is one of the retrofitting method of RC members, can enhance strength and stiffness of original RC column with enlarged section and provide uniformly distributed lateral load capacity throughout the structure. The experimental studies have been conducted by many researchers to analyze seismic performance of seismic strengthened RC column. However, structures which have plan and vertical irregularities shows torsional behavior, and therefore it causes large deformation on RC column when subjected to seismic load. Thus, test results from concentric cyclic loading can be overestimated comparing to eccentric cyclic test results, In this paper, two kinds of eccentric loading pattern was suggested to analyze structural performance of RC columns, which are strengthened by concrete jacketing method with new details in jacketed section. Based on the results, it is concluded that specimens strengthened with new concrete jacketing method increased 830% of maximum load, 150% of maximum displacement and changed the failure modes of non-strengthened RC columns.

• 한국지진공학회논문집
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• 제8권6호통권40호
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• pp.45-54
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• 2004

최근 강구조물의 장경간화 및 고층화로 인하여 고강도강재의 사용이 점차 증가하고 있다. 고강도강재(POSTEN60, POSTEN80)가 적용된 강구조물의 정확한 내진설계를 위해서는 반복하중 작용시 발생하는 대변형 및 비선형반복거동을 구현할 수 있는 해석기법이 필요하다. 본 연구에서는 고강도강재의 단조재하실험 및 반복하중실험을 기초하여 반복소성모델을 제안하였다. 제안된 소성모델과 유한변위이론을 적용한 3차원 탄소성 유한변위해석기법을 개발하였으며 이를 실험값과 비교하여 검증하였다. 검증된 3차원 탄소성 유한변위해석을 이용하여 고강도 원형강교각의 내진해석을 수행하였다. 또한, 고강도 원형강교각의 지름-두께비에 따른 내진성능을 명확히 하였다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.157-162
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• 2007

Geophysical survey has been conducted on the continental margin off the South Shetland Islands aboard R/V Onnuri of KORDI in 1992/1993. About 800-line km of 96-channel reflection data have been acquired. On the seismic section, BSR with strong reflectivity and negative polarity has been found at 700 ms below the sea bottom. BSR is considered as the base of gas hydrates and AVO analysis was performed to study physical properties along BSR. True amplitude recovery and surface consistence amplitude were applied to seismic data and angle gathers were obtained. AVO gradient and AVO intercept are calculated on every CDP gather. Section of AVO intercept show strong reflectivity and negative polarity on BSRs and stronger continuity of BSR than stacked section. Cross plot of intercept-gradient indicates that the lower layer below BSR is filled with free gas.

• 한국지진공학회논문집
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• 제25권5호
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• pp.191-199
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• 2021

In seismic design, hollow section concrete columns offer advantages by reducing the weight and seismic mass compared to concrete section RC bridge columns. However, the flexure-shear behavior and spirals strain of hollow section concrete columns are not well-understood. Octagonal RC bridge columns of a small-scale model were tested under cyclic lateral load with constant axial load. The volumetric ratio of the transverse spiral hoop of all specimens is 0.00206. The test results showed that the structural performance of the hollow specimen, such as the initial crack pattern, initial stiffness, and diagonal crack pattern, was comparable to that of the solid specimen. However, the lateral strength and ultimate displacement of the hollow specimen noticeably decreased after the drift ratio of 3%. The columns showed flexure-shear failure at the final stage. Analytical and experimental investigations are presented in this study to understand a correlation confinement steel ratio with neutral axis and a correlation between the strain of spirals and the shear resistance capacity of steel in hollow and solid section concrete columns. Furthermore, shear strength components (V_c, V_s·, V_p) and concrete stress were investigated.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.619-627
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• 2005

An initial member sections of steel structures is selected by experience of expert building structural designers. And appropriate member section is designed by repeat calculation through structural analysis. Therefore an initial assumption of member section is necessary for saving the time for structural design and is important to acquire safety of building structures. Also brace damper are generally used to prevent or decrease structural damage by its hysteretic behavior in building structures subjected to strong earthquake. Based on plastic design, the initial section of members for architectural steel structures with brace hysteretic dampers is presented and seismic effect of structural behavior by the ratio of damper stiffness to structural story stiffness is estimated in this paper.

• 한국지진공학회논문집
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• 제21권4호
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• pp.189-195
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• 2017

In the seismic design of building structural members, due to the complexity of the placement of PC steels in prestressed concrete members, it is necessary to review and define the definition of member damage in comparison with reinforced concrete members. In this study, the results of past experiments compared with the calculation results by 'section Analysis Method', with the aim of reviewing the precision of calculation results when member damage evaluation is performed using the section analysis method. Furthermore, it is also compared with the calculation results by the 'split Element Method'. In addition, parametric studies were carried out, and the influence of the difference between the amount of PC steels and reinforced bar on the residual strain was examined.

• 지구물리와물리탐사
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• 제12권3호
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• pp.255-262
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• 2009

가스하이드레이트 개발 시 중요한 요소 중의 하나인 가스하이드레이트 부존층의 정확한 심도를 얻기 위해서는 일반적으로 고해상도 정보를 주는 VSP 탐사가 많이 수행되어왔다. 본 연구에서는 가스하이드레이트 부존지역인 울릉분지 지역의 UBGH09 시추공에서 국내 최초로 삼성분 지오폰을 사용하여 획득한 제로오프셋 VSP 탐사자료로부터 구간속도를 추출하고 corridor 중합단면도를 생성하여 지표탄성파탐사 자료와 비교해 보았다. 먼저 Phase rotation을 통하여 삼성분 지오폰으로 기록된 신호들이 실제 수직 및 두 개의 수평성분 자료들이 되도록 변환 시키고, 파동장 분리과정을 통하여 직접파와 반사파를 분리하였다. 제로오프셋 VSP 자료의 직접파로부터 추출한 구간속도를 음파검층의 구간속도와 비교한 결과 두 구간속도 모두 비슷한 양상을 나타냈다. BSR 상부의 하이드레이트 층에서는 빠른 속도를 보이고 BSR 하부에서 속도가 급격히 떨어지는 것으로 보아 BSR 하부에 유리가스가 집적되어 있는 것으로 보인다. 제로오프셋 VSP 반사파 자료로부터 corridor 중합단면도를 생성하여 지표탄성파탐사의 CMP 중합단면도와 비교한 결과 대부분의 반사이벤트들이 잘 부합하였으며, phase rotation을 적용한 결과가 phase rotation을 적용하지 않았을 경우보다 더 잘 부합하였다.또한 transverse 성분을 이용하여 만든 corridor 중합단면도와 지표탄성파 CMP 중합단면도를 비교한 결과 지표탄성파 CMP 중합 단면도 내의 모오드 변환된 PS 반사파들을 확인할 수 있었다.