Theoretical strength assessment of unstiffened bilge shell plating and some considerations on rule prescriptions

Tetsuo Okada, Takashi Toyama, Yasumi Kawamura

Abstract

In ship hull structures, bilge part is often composed of unstiffened radiused plating, for which the harmonized CSR stipulates required scantlings, locations of the longitudinals adjacent to the bilge radius, and so on. In recent years, under the increased demand for rational structural design, larger radius than ever is sought, expecting reduction of hull steel weight and welding lengths, thus contributing to the reduction of production cost of structures. However, structural problems arising from the larger bilge radius and associated structural arrangement around the bilge shell are not yet sufficiently identified. In these circumstances, the authors developed theoretical formulae, assuming radiused plating connected to continuous stiffened flat plating with regular stiffener spacing. The results of the theoretical calculations are compared with the results of finite element analysis, and it was found that the derived theoretical formulae well explain the complicated phenomena of the curved shell plating connected to the flat stiffened panels. Utilizing the derived theoretical formulae, parametric studies were carried out with regard to the radius of the bilge shell plating, the distance between the position where the curvature of the bilge plate starts and the adjacent longitudinal, and so on. As a result of the calculations, it was found that large bilge radius exceeding current usual practice is feasible, on the condition that the location of the longitudinals is well controlled to reduce bending stresses on the shell plate, and the buckling strength is satisfied. In such case, the stipulation in the harmonized CSR is not always rational, and the authors propose modified structural design methodologies around the unstiffened bilge shell plating.

Original languageEnglish
Pages (from-to)1-16
Number of pages16
JournalJournal of Marine Science and Technology (Japan)
DOIs
StateAccepted/In press - 2016 Jun 9

Fingerprint

shell
hull
buckling
welding
production cost
curvature
spacing
steel
methodology

Keywords

  • Bilge shell plating
  • Harmonized CSR
  • Structural rules

ASJC Scopus subject areas

  • Ocean Engineering
  • Mechanics of Materials
  • Mechanical Engineering
  • Oceanography

Cite this

@article{390cc96c5eba4e09b40ba65c6eb3f323,
title = "Theoretical strength assessment of unstiffened bilge shell plating and some considerations on rule prescriptions",
keywords = "Bilge shell plating, Harmonized CSR, Structural rules",
author = "Tetsuo Okada and Takashi Toyama and Yasumi Kawamura",
year = "2016",
month = "6",
doi = "10.1007/s00773-016-0392-z",
pages = "1--16",
journal = "Journal of Marine Science and Technology (Japan)",
issn = "0948-4280",
publisher = "Springer Japan",

}

TY - JOUR

T1 - Theoretical strength assessment of unstiffened bilge shell plating and some considerations on rule prescriptions

AU - Okada,Tetsuo

AU - Toyama,Takashi

AU - Kawamura,Yasumi

PY - 2016/6/9

Y1 - 2016/6/9

N2 - In ship hull structures, bilge part is often composed of unstiffened radiused plating, for which the harmonized CSR stipulates required scantlings, locations of the longitudinals adjacent to the bilge radius, and so on. In recent years, under the increased demand for rational structural design, larger radius than ever is sought, expecting reduction of hull steel weight and welding lengths, thus contributing to the reduction of production cost of structures. However, structural problems arising from the larger bilge radius and associated structural arrangement around the bilge shell are not yet sufficiently identified. In these circumstances, the authors developed theoretical formulae, assuming radiused plating connected to continuous stiffened flat plating with regular stiffener spacing. The results of the theoretical calculations are compared with the results of finite element analysis, and it was found that the derived theoretical formulae well explain the complicated phenomena of the curved shell plating connected to the flat stiffened panels. Utilizing the derived theoretical formulae, parametric studies were carried out with regard to the radius of the bilge shell plating, the distance between the position where the curvature of the bilge plate starts and the adjacent longitudinal, and so on. As a result of the calculations, it was found that large bilge radius exceeding current usual practice is feasible, on the condition that the location of the longitudinals is well controlled to reduce bending stresses on the shell plate, and the buckling strength is satisfied. In such case, the stipulation in the harmonized CSR is not always rational, and the authors propose modified structural design methodologies around the unstiffened bilge shell plating.

AB - In ship hull structures, bilge part is often composed of unstiffened radiused plating, for which the harmonized CSR stipulates required scantlings, locations of the longitudinals adjacent to the bilge radius, and so on. In recent years, under the increased demand for rational structural design, larger radius than ever is sought, expecting reduction of hull steel weight and welding lengths, thus contributing to the reduction of production cost of structures. However, structural problems arising from the larger bilge radius and associated structural arrangement around the bilge shell are not yet sufficiently identified. In these circumstances, the authors developed theoretical formulae, assuming radiused plating connected to continuous stiffened flat plating with regular stiffener spacing. The results of the theoretical calculations are compared with the results of finite element analysis, and it was found that the derived theoretical formulae well explain the complicated phenomena of the curved shell plating connected to the flat stiffened panels. Utilizing the derived theoretical formulae, parametric studies were carried out with regard to the radius of the bilge shell plating, the distance between the position where the curvature of the bilge plate starts and the adjacent longitudinal, and so on. As a result of the calculations, it was found that large bilge radius exceeding current usual practice is feasible, on the condition that the location of the longitudinals is well controlled to reduce bending stresses on the shell plate, and the buckling strength is satisfied. In such case, the stipulation in the harmonized CSR is not always rational, and the authors propose modified structural design methodologies around the unstiffened bilge shell plating.

KW - Bilge shell plating

KW - Harmonized CSR

KW - Structural rules

UR - http://www.scopus.com/inward/record.url?scp=84976314696&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84976314696&partnerID=8YFLogxK

U2 - 10.1007/s00773-016-0392-z

DO - 10.1007/s00773-016-0392-z

M3 - Article

SP - 1

EP - 16

JO - Journal of Marine Science and Technology (Japan)

T2 - Journal of Marine Science and Technology (Japan)

JF - Journal of Marine Science and Technology (Japan)

SN - 0948-4280

ER -