Jeong-Gon Ha

Soil-Rounding Effect on Embedded Rocking Foundation via Horizontal Slow Cyclic Tests

AbstractThe rocking behavior of a shallow foundation of a bridge pier has emerged as an effective mechanism for reducing the seismic load on the superstructure during a strong earthquake. However, ...

Comparison between cyclic and dynamic rocking behavior for embedded shallow foundation using centrifuge tests

Designs allowing the rocking behavior of the foundation during earthquake have been introduced to reduce the seismic load on the superstructure and the ductility demand on the structural column. In addition, several studies have been conducted on rocking foundation based on the slow cyclic and dynamic tests by assuming the structure as a rigid oscillator. However, when structural bending is included, the rocking behaviors of the foundation for the slow cyclic and dynamic tests are different. Therefore, a clear description of each method and how each behavior is different should be investigated by considering structural bending motion. To fill the gap between cyclic and dynamic rocking behaviors, embedded foundation models with various slenderness ratios of the systems were investigated using horizontal slow cyclic tests and dynamic tests in a centrifuge. Test results show that the rocking foundation was affected by structural bending. The overturning moment in the dynamic test determined by the conventional method was different compared with results obtained from the slow cyclic test due to the structural bending motion. Finally, the overturning moment was re-evaluated by considering structural net displacement, and the re-evaluated dynamic overturning moment matched the results from the slow cyclic tests.

Overview on Standards for Soil－Structure Interaction Analysis used in Design of Infrastructure

현행 국내 내진 성능 평가 기준에서 사용하고 있는 필댐의 동적 상세 해석에 대한 안전성 평가 기준은 지진 하중 조건에의해 발생되는 댐마루 연직방향, 횡방향 최대 변위가 정적하중에 의한 변위를 포함하여 제체 높이의 1% 이하로 규정하고 있다. 그러나 이는 이론적 근거가 부족하여, 평가 기준에 대한 합리성 검토가 필요하다. 중약진 지역에 속하는 국내 지진학적 특성상 지진시 댐 계측 데이터로 근거를 마련하기가 어려운 실정으로, 본 연구에서는 국외 계측 데이터 D/B 등 다양한 자료를 바탕으로 안전성 평가 기준을 검토하였다. 추가적으로 원심모형시험과 수치해석을 함께 수행하여, 변형 기준을 검토하였다. 또한, 수치시뮬레이션을 통하여 매개 변수 분석을 수행하고, 댐체의 횡방향 변위와 침하에 대한 영향을 분석하고 변형 기준과 비교, 검토하였다.

Seismic Bearing Capacity of Shallow Foundation Supporting Single-Degree-of-Freedom Structures

규사모래지반에 대하여 동적원심모형 시험과 3차원 시간영역 양해법을 적용한 수치해석을 이용하여 단자유도 얕은 기초 구조물의 지진시 지지력 평가를 수행하였다. 수치해석은 동적원심모형 시험의 원형스케일로 시행되었다. 수치해석결과는 실험 계측결과와 매우 일치하는 해석결과를 나타내었다. 본 논문에서는 검증된 수치해석결과로 부터 기초면 하 접지압을 획득하여 지진시...

Simulation of Dynamic in-situ Soil Properties for the Centrifuge Test (Hualien Site in Taiwan)

The simulation of the field dynamic soil properties for soil modeling in the centrifuge test is important. In this study, the process of soil modeling based on the shear wave velocity profile is developed. From the resonant column test in each confining pressure, the shear wave velocity profile is expected and the modeling condition is determined by comparing it with that in the field. During the dynamic centrifuge test, the bender element test is performed for measuring the in-flight shear wave velocity profile, and the applicability of the proposed method was verified. This modeling method is applied to the centrifuge test of the Hualien Large-Scale Seismic test.