LONG-TERM PREDICTIONS OF WAVE BENDING MOMENT (PART I AND PART II)

It has become possible lately to predict the long-term distribution of wave bending moment induced on a ship hull by using the statistical wave data collected on the world sea areas and routes. Investigations were made, in Part I, to establish tentatively the standard family of wave spectra for the short- and long-term predictions of wave bending moment in ocean waves based on such wave statistics. The theoretical formulations of wave spectrum originally proposed by Neumann, Darbyshire, Roll-Fischer and Pierson- Moskowitz were modified so as to fit the observed sea state and compared with one another. Further, the comparative investigations were carried out on the standard deviations of wave bending moment for two ships in rough seas, which were obtained by using those modified wave spectra and the calculated response operators of wave bending moment. According to those investigations, it was concluded that the modified Pierson-Moskowitz wave spectrum (ISSC spectrum) would be appropriate for the purpose of the short- and long-term predictions of wave bending moment and might be acceptable as an interim proposal for the family of wave spectra. In Part II, the long-term predictions of wave bending moment were carried out on three kinds of hull forms, where the similar ships having the different lengths were assumed for each hull form in order to investigate the relationship between the ship size and the wave bending moment. In the first place, the standard deviations of wave bending moment induced on the ship hulls in short-term irregular seas were evaluated based on the linear superposition method by using the modified Pierson-Moskowitz wave spectra (ISSC spectra) and the calculated response operators of wave bending moment. Then, the long-term distributions of wave bending moment were predicted by utilizing the long- term wave data on the North Atlantic. According to the predicted results, there were found the trends of extreme wave bending moment. That is, the effective wave height corresponding to the extreme wave bending moment amidships increases generally with increase of ship length but takes on unexpectedly large values for small ships of about 100 meters length and holds nearly constant for large ships longer than about 300 meters.

• Corporate Authors:

  Society of Naval Architects of Japan

  23 Shiba-kotohiracho, Minato-ku
  Tokyo 135,   Japan 
• Authors:
  • Fukuda, J
• Publication Date: 1970

Media Info

• Pagination: p. 35-55
• Serial:
  • Selected Papers, J of Soc of Naval Arch of Japan
  • Volume: 5
  • Publisher: Society of Naval Architects of Japan

Subject/Index Terms

• TRT Terms: Bending moments; Hulls; Hydrodynamics; Loads; Technology; Wave measurement; Waves
• Old TRIS Terms: Hull bending moments; Wave force analysis; Wave induced loads
• Subject Areas: Design; Hydraulics and Hydrology; Marine Transportation;

Filing Info

• Accession Number: 00035076
• Record Type: Publication
• Source Agency: Society of Naval Architects of Japan
• Files: TRIS
• Created Date: Oct 27 1972 12:00AM