• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.189-196
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• 2002

The capacity of CFS piers has not been used to a practical design, because there is no guide of a seismic design for CFS piers. Therefore, the guide of a seismic design value is derived from tests of CFS piers in order to apply it to a practical seismic design. Steel piers and concrete-filled steel piers are tested with constant axial load using quasi-static cyclic lateral load to check ductile capacity and using the real Kobe ground motion of pseudo-dynamic test to verify seismic performance. The results prove that CFS piers have more satisfactory ductility and strength than steel piers and relatively large hysteretic damping in dynamic behaviors. The seismic performance of steel and CFS piers is quantified on the basis of the test results. These results are evaluated through comparison of both the response modification factor method by elastic response spectrum and the performance-based design method by capacity spectrum and demand spectrum using effective viscous damping. The response modification factor of CFS piers is presented to apply in seismic design on a basis of this evaluation for a seismic performance.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.197-204
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• 2002

The resent earthquakes in worldwide have caused extensive damage to highway reinforced concrete bridge piers. It has been observed in the Korean Peninsula that the number of minor or low earthquake motions have increased year by year. Since the concern about the earthquake hazards is increased, the objective of this research is to evaluate the damage of reinforced concrete bridge piers subjected to probable earthquake motions. Experimental investigation was conducted to study the seismic performance of the full-scale specimens in size D=1.2m H=4.8m, which were constructed with different longitudinal lap splice and loading pattern, through the quasi-static test and the pseudo-dynamic test. It is thought that this result could contribute to establish the retrofit decision-making and disaster planning of reinforced concrete bridge piers in earthquake regions. And it could be also possible to quantify the damage of reinforced concrete bridge piers under cyclic loading

• Earthquakes and Structures
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• 제7권6호
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• pp.1001-1024
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• 2014

The size of spread footings was found to be unnecessarily large from some actual engineering practices constructed in Taiwan, due to the strict design provisions related to footing uplift. According to the earlier design code in Taiwan, the footing uplift involving separation of footing from subsoil was permitted to be only up to one-half of the foundation base area, as the applied moment reaches the value of plastic moment capacity of the column. The reason for this provision was that rocking of spread footings was not a favorable mechanism. However, recent research has indicated that rocking itself may not be detrimental to seismic performance and, in fact, may act as a form of seismic isolation mechanism. In order to clarify the effects of the relative strength between column and foundation on the rocking behavior of a column, six circular reinforced concrete (RC) columns were designed and constructed and a series of rocking experiments were performed. During the tests, columns rested on a rubber pad to allow rocking to take place. Experimental variables included the dimensions of the footings, the strength and ductility capacity of the columns and the intensity of the applied earthquake. Experimental data for the six circular RC columns subjected to quasi-static and pseudo-dynamic loading are presented. Results of each cyclic loading test are compared against the benchmark test with fixed-base conditions. By comparing the experimental responses of the specimens with different design details, a key parameter of rocking behavior related to footing size and column strength is identified. For a properly designed column with the parameter higher than 1, the beneficial effects of rocking in reducing ductility and the strength demand of columns is verified.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.93-96
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• 2008

근단층지반운동(NFGM)은 장주기 성분의 펄스 형태를 갖는 지반운동이다. 이들 근단층지반운동은 1994년 미국 Northridge 지진, 1995년 일본 Kobe 지진, 1999년 터키 Izmit 지진 등과 같은 강진 지역에서 관측되었으며 이들 지진의 진앙이 도시 주변에 위치하여 큰 피해를 초래한 바 있다. 강진 지역에서는 원역단층지반운동(FFGM)에 대해 폭넓은 연구가 수행되었으나 비내진 또는 중저진 지역에서는 NFGM에 대한 연구가 미흡한 실정이다. 이 연구는 주철근 겹침이음이 없는 RC 교각을 근단층지반운동에 대해서 해석 연구하는 것이다. 2기의 RC교각은 진동대 실험으로 근단층지반운동을 가력하였다. 추가로 2기의 RC교각은 준정적 실험으로 나머지 2개의 RC교각은 유사동적 실험으로 수행하였다. 이 논문은 횡방향 철근비가 증가 할수록 더 큰 PGA에서 철근이 파괴된다는 것을 보여준다.

• 농업과학연구
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• 제47권4호
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• pp.963-978
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• 2020

Earthquakes can induce a large number of landslides and cause very serious property damage and human casualties. There are two issues in study on earthquake-induced landslides: (1) slope stability analysis under seismic loading and (2) debris flow run-out analysis. This study aims to review technical studies related to the development and application of earthquake-induced landslide models (seismic slope stability analysis). Moreover, a pilot application of a physics-based slope stability model to Mt. Umyeon, in Seoul, with several earthquake scenarios was conducted to test regional scale seismic landslide mapping. The earthquake-induced landslide simulation model can be categorized into 1) Pseudo-static model, 2) Newmark's dynamic displacement model and 3) stress-strain model. The Pseudo-static model is preferred for producing seismic landslide hazard maps because it is impossible to verify the dynamic model-based simulation results due to lack of earthquake-induced landslide inventory in Korea. Earthquake scenario-based simulation results show that given dry conditions, unstable slopes begin to occur in parts of upper areas due to the 50-year earthquake magnitude; most of the study area becomes unstable when the earthquake frequency is 200 years. On the other hand, when the soil is in a wet state due to heavy rainfall, many areas are unstable even if no earthquake occurs, and when rainfall and 50-year earthquakes occur simultaneously, most areas appear unstable, as in simulation results based on 100-year earthquakes in dry condition.

• 한국지반환경공학회 논문집
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• 제24권2호
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• pp.13-24
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• 2023

Tunnels may undergo a larger or a smaller response compared with the free-field soil. In the pseudo-static procedure, the response of the tunnel is most often characterized by a curve that relates the racking ratio (R) with the flexibility ratio (F), where R represents the ratio of the tunnel response with respect to the free-field vibration and F is the relative stiffness of the tunnel and the surrounding soil. A set of analytical and empirical curves that do not account for the depth and the aspect ratio of the tunnel are typically used in practice. In this study, a series of dynamic analyses are conducted to develop a set of F-R_m relations for use in a frame analysis method. R_m is defined as an adjusted R where the rocking mode of deformation is removed and only the racking deformation is extracted. The numerical model is validated against centrifuge test recordings. The influence of aspect ratio, buried depth of tunnel on results is investigated. The results show that R_m increases with the increase of the buried depth and the aspect ratio. The widely used F-R relations are highlighted to be different compared with the obtained results in this study. Therefore, the updated F-R_m relations with proposed equations are recommended to be used in practice design. The rocking response decreases with either the decrease of the difference of stiffness between surrounding soil and tunnel or the larger aspect ratio of the tunnel section.

• 한국군사과학기술학회지
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• 제17권6호
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• pp.844-852
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• 2014

PBX simulant is known to exhibit highly nonlinear behaviors of deformation such as the stress softening, hysteresis under cyclic loading, residual strain after unloading, and aging. This paper proposes a new pseudo-elastic model for PBX simulant considering stress softening and residual strain. Uniaxial loading and unloading tests at quasi-static states were carried out in order to obtain the mechanical properties of the PBX simulants. And then the Dorfmann-Ogden model is modified to make it consistent with the test result of PBX simulants. Prediction with the new model shows a good correspondence to the experimental data demonstrating that the model properly describes stress softening and residual strain of PBX simulants.

• 한국지진공학회논문집
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• 제6권5호
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• pp.53-58
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• 2002

최근, 콘크리트 충전 강교각은 신속한 시공과 뛰어난 연성능력으로 인해 도심지에서 철근 콘크리트 교각의 대안이 되고 있다. 이러한 콘크리트 충전 강교각은 내진 설계에서도 훌륭한 성능을 발휘할 수 있으나 내진 설계의 가이드가 없어 내진 설계시 그 성능을 모두 반영하지 못하고 있는 상황이다. 이에 실제 적용을 위해 콘크리트 충전 강교각 실험으로부터 얻어진 실험치로부터 내진 설계에 지침이 될 수 있는 가이드를 제시하고자 한다. 콘크리트 충전 강교각과 일반 강교각의 연성 능력을 평가하기 위해 준 정적 반복 재하 실험을 수행하고, 지진 거동을 검증하기 위해 고베 지진을 입력 데이타로 한 유사 동적 실험을 수행한다. 콘크리트 충전 강교각은 일반 강교각에 비해 만족할 만한 연성도와 강도를 보이고, 동적 거동은 상대적으로 큰 이력감쇠를 증명한다. 실험으로 얻어진 데이터를 근거로 하여 콘크리트 충전 강교각의 내진 성능을 정량화 하고, 탄성응답 스펙트럼에 의한 지진응답 수정계수법과 유효 점성 감쇠를 이용한 성능 곡선 및 요구 스펙트럼에 의한 성능기초 설계법의 비교를 통하여, 콘크리트 충전 강교각과 일반 강교각의 내진 성능을 평가한다. 이러한 내진 성능 평가를 기초로 하여, 일반 강교각과 더불어 내진 설계에 적용할 수 있는 콘크리트 충전 강교각의 지진응답 수정계수를 제시한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.93-96
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• 2008

이 논문은 근단층지반운동(NFGM)하에서 내진성능을 평가하기 위한 RC교각의 진동대, 준정적, 유사동적 실험을 다룬다. 5개의 실험체가 수행되었다. 축소 모형을 제작하고 상부구조물의 중량 에 의한 축력의 효과는 프리스트레스에 의해 구현하였다. 지진이 발생할 때 상부 구조물의 횡방향 관성력은 진동대의 제한된 용량 때문에 교각 실험체에 연결한 질량 프레임으로 모사하였다. 특히, 진동대 실험에서 질량 모사 프레임이 교각 모델과 같은 변위로 움직이면서 마찰 효과를 최소화할 수 있도록 고려하였고 이에 대한 검증을 실시하였다. RC교각의 축소 계수를 4.25로 설정 하였다.

• 한국가구학회지
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• 제25권4호
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• pp.331-337
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• 2014

The purpose of this paper is to evaluate the moment resistance of glulam post-to-base connections by applying quasi-static cyclic loads. The connectors consisted of inserted plates and drifted pins according to the load direction. The connection types employed in this study were total three including two unidirectional types (H, V) and the multi-directional type (M). The moment resistance of 8 mm-plate M-type is compared to 6 mm plate. Total four types of Post-to-base connection are prepared and tested under pseudo-static reversed cyclic loading. Test results showed that the yield moment of multi-directional connection is about 2 times higher than that uni-directional connections. The ductility ratio of multi-directional connection determined by EEEP was higher that that of uni-directional connection. It was becoming higher as the thickness of plate is increased. The Finite Element Analysis was conducted to estimate the stress distribution behavior of tested connections. Results showed the failure of multi-directional type were caused by the split of pined hole and the shear failure of lifted part of post.