• 제목/요약/키워드: Hammering test

검색결과 23건 처리시간 0.02초

해상풍력타워 석션기초의 설치시 거동에 대한 모형 시험 연구 (Installation of Suction Caisson Foundation for Offshore Wind Turbine : Model Test)

  • 김동준;김수린;추연욱;김동수;이만수
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2010년도 추계 학술발표회
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    • pp.825-839
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    • 2010
  • The global and domestic market for offshore wind farm is expected to grow fast, and the design and installation of substructure and foundation is getting more important. As for the offshore wind farms located in the shallow(depth < 20m) water, the construction and installation of the substructure and foundation makes up about 1/4 ~1/3 of the offshore wind farm construction cost, and the portion is expected to increase because the turbine capacity is increasing from 2 ~ 3MW to 5MW or larger and the water depth of wind farms is also increasing over 30m. As a foundation for offshore wind turbine, the suction caisson foundation is being considered to be a highly competitive alternative to the conventional monopile or gravity based structure, because it has features suitable for the offshore construction such as quick installation, no heavy equipment for penetration and no hammering noise for driving. In order to study the installation behaviour of the suction caisson, laboratory tests were performed with sand. The pore water pressure and displacement were measured to analyze the suction pressure during penetration, the penetration speed and the amount of heaving.

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랜덤 감쇠기법을 이용한 분할모형의 접수 감쇠계수 추정 (Wet Damping Estimation of the Segmented Hull Model using the Random Decrement Technique)

  • 김유일;박성건
    • 대한조선학회논문집
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    • 제50권4호
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    • pp.217-223
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    • 2013
  • This paper presents the wet damping estimation of the segmented hull model using the random decrement technique together with the continuous wavelet transform. The tested 16 sea states are grouped together based on the speed of the ship in order to figure out the possible influence of the ship speed on the damping ratio. The measured time histories of vertical bending moment for each tested sea state were processed with random decrement technique to derive the free decay signal, from which the damping ratios are estimated. Also, the autocorrelation functions of the filtered signal were calculated and comparison was made with the free decay signal obtained from the random decrement technique. Then the wet damping ratios for each sea state group, as well as precise wet natural frequencies, are estimated by using continuous wavelet transform. It turned out that the wet natural frequencies derived from the measured signal did not show any significant discrepancy compared with those obtained by wet hammering test, whereas the damping ratio did. It was considered that the discrepancy of the damping ratio between in calm and moving water may be attributed to the viscous effects caused by dramatically different flow pattern and relative velocity between the vibrating structure and surrounding fluid particles.

도로시설물 적용 앵커볼트 결함 검출을 위한 비파괴(Ultrasonic) 검사 기법 적용에 대한 연구 (A Study on the Application of Non-destructive (Ultrasonic) Inspection Technique to Detect Defects of Anchor Bolts for Road Facilities)

  • 서동우;김재환;이진혁;조한민;박상기;김민수
    • 한국방재안전학회논문집
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    • 제15권4호
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    • pp.11-20
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    • 2022
  • 국내의 앵커볼트 일반 비파괴 검사법은 육안검사와 타음검사를 적용하고 있으나, 육안검사는 기초에 포함된 부분이나 너트 및 베이스 플레이트가 설치된 부분에서 앵커볼트의 부식이나 피로균열 등을 확인하는 것이 어렵다. 타음검사는 주변 환경과 개인차에 의한 영향을 받기 때문에 객관적인 조사가 어려운 것이 현실이므로 이러한 결함을 정량적으로 추정할 수 있는 비파괴 검사 기술개발이 필요하다. 국내 도로시설물 앵커볼트의 점검은 육안조사를 수행하고 있으며, 교량받침, 낙교방지시설 등의 앵커볼트 중요도가 높으므로 기존 점검방법과 함께 비파괴검사 기술을 개발하여 앵커볼트의 예방정비를 통해 교량 수명연장에 기여할 필요가 있다. 본 기술 개발을 통해 현재 수행하고 있지 않은 앵커볼트의 비파괴검사를 수행함으로 도로시설물 앵커볼트의 선제적/능동적 유지관리가 가능한 기술로 연구개발 및 실용화가 시급하다. 본 논문에서는 비파괴 검사 기법 중 초음파탐상법(Ultrasonic test)을 적용하여 부식, 균열 등 앵커볼트의 결함 검출 가능성 및 실뢰도를 실험적으로 검증하였다. 기술 개발이 완성되면 검사 신뢰성 향상 원천기술 확보로 앵커볼트에 대한 선제적/능동적 유지관리의 실현이 가능할 것으로 기대된다.