Journal of Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회논문집)

Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회)
권호 표지
DOI QR코드

DOI QR Code

Uncertainty Analysis of Wave Forces on Upright Sections of Composite Breakwaters

혼성제 직립벽에 작용하는 파력의 불확실성 해석

  • Lee, Cheol-Eung (Department of Civil Engineering, Kangwon National University)
  • Received : 2011.02.19
  • Accepted : 2011.06.13
  • Published : 2011.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

A MCS technique is represented to stochastically analyze the uncertainties of wave forces exerted on the upright sections of composite breakwaters. A stochastical models for horizontal and uplift wave forces can be straightforwardly formulated as a function of the probabilistic characteristics of maximum wave height. Under the assumption of wave forces followed by extreme distribution, the behaviors of relative wave forces to Goda's wave forces are studied by the MCS technique. Double-truncated normal distribution is applied to take the effects of uncertainties of scale and shape parameters of extreme distribution into account properly. Averages and variances of relative wave forces are quantitatively calculated with respect to the exceedance probabilities of maximum design wave height. It is found that the averages of relative wave forces may be decreased consistently with the increases of the exceedance probabilities. In particular, the averages on uplift wave force are evaluated slightly larger than those on horizontal wave force, but the variations of coefficient of the former are adversely smaller than those of the latter. It means that the uncertainties of uplift wave forces are smaller than those of horizontal wave forces in the same condition of the exceedance probabilities. Therefore, the present results could be useful to the reliability based-design method that require the statistical properties about the uncertainties of wave forces.

혼성제 케이슨에 작용하는 파력의 불확실성을 확률론적으로 해석할 수 있는 MCS 기법을 제시하였다. 수평파력 및 양력에 대한 확률론적 산정모형을 파력 산정에 사용되는 최대파고의 확률적 특성의 함수로 수립하였다. 파력이 극치분포를 따른다는 가정하에 Goda 식으로부터 산정된 수평파력과 양력에 대한 상대파력의 개념으로 파력의 거동특성을 해석하였다. 이중절단형 정규분포를 이용하는 MCS 기법을 이용하여 축척모수와 형상모수의 불확실성을 고려하였다. 최대설계파고의 초과확률에 따라 상대파력의 평균과 분산을 정량적으로 산정하였다. 해석 결과에 의하면 초과확률이 커짐에 따라 수평파력 및 양력에 대한 상대파력의 평균은 일정하게 감소된다. 특히 양력에 대한 상대 파력은 그 평균값이 수평파력의 평균보다 크고 변동계수는 작게 산정되었다. 이는 동일조건의 초과수준에서 양력에 대한 불확실성이 상대적으로 수평파력의 불확실성보다 작다는 것을 의미한다. 따라서 본 연구의 결과는 파력의 불확실성에 대한 통계적 거동특성을 요구하는 신뢰성 설계 등에서 유용하게 이용될 수 있다.

Keywords

References

  1. Bruining, J. W. (1994). Wave forces on vertical breakwaters, Reliability of design formula. MSc. Thesis, Delft Univ. of Technology.
  2. Coastal Engineering Research Center. (2006). CEM(Coastal Engineering Manual), US Army Corps Engineers, Washington D.C., USA.
  3. Franco, C., Van der Meer, J. W. and Franco, L. (1996). Multidirectional wave loads on vertical breakwaters. Proc. 25th. Int. Coast. Engrg. Conf., ASCE, 2008-2021.
  4. Goda, Y. (1974). New wave pressure formula for composite breakwaters. Proc. 14th. Int. Coast. Engrg. Conf., ASCE, 1702-1720.
  5. Goda, Y. (2000). Random seas and design of maritime structures. Univ. of Tokyo Press, Tokyo.
  6. Hiroi, I. (1919). On a method of estimating the force of waves. Memoirs of Engrg. Faculty, Imperial Univ., X(1), 19.
  7. Minikin, R. R. (1950). Wind, waves and maritime structures. Charles Griffin and Co., Ltd., London, U.K.
  8. Sainflou, G. (1928). Essai sur les diques maritimes verticales. Annales des Ponts et Chausees, 98(4).
  9. Sarpkaya, T. and Isaacson, M. (1981). Mechanics of wave forces on offshore structures. Van Nostrand Reinhold Co., NewYork.
  10. Takahashi, S., Tanimoto, K. and Shimosako, K. (1994). A proposal of impulsive pressure coefficient for the design of composite breakwaters. Proc. Int. Conf. Hydro- Technical Engrg. for Port and Harbor Constr. (Hydro-Port '94) Yokosuka, 489-504.
  11. Tanimoto, K., Moto, K., Ishizuka, S. and Goda, Y. (1976). An investigation on design wave force formulae of composite-type breakwaters, Proc. 23rd Japanese Conf. Coastal Engrg., 11-16.
  12. Tanimoto, K., Takahashi, S. and Kitatani, T. (1981). Experimental study of impact breaking wave forces on a vertical-wall caisson of composite breakwaters. Rept. Port and Harbor Res. Inst., 20(2), 3-39.
  13. The Overseas Coastal Area Development Institute of Japan. (2009). Technical Standard and Commentaries for Port and Harbour Facilities in Japan, Ports and Harbours Bureau, Ministry of Land, Infrastructures, Transport and Tourism(MLIT),Japan.