Section 2 Nomenclature and design factors
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Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 1 Ship Structures - Part 7 Enhanced Structural Assessment (Provisional) - Chapter 2 Total Design Loads - Section 2 Nomenclature and design factors

Section 2 Nomenclature and design factors

Parent topic: Chapter 2 Total Design Loads

2.1 Nomenclature

2.1.1 The nomenclature used in this Chapter to describe the loads applied to or reacted by the structure and local dimensional characteristics, e.g. breadths and spans, is based on the following format:

  1. A Suffix

where

The letter A is the load type or dimension letter and is one of the following:

Load types

P = denotes an applied normal pressure load, i.e. normal to the plate.
P = denotes an applied impulse or impact pressure load.
F = denotes an applied point load due to gravity and mass inertial effects.
LV = denotes an internally generated load acting in the predominantly vertical direction as a consequence of applied forces and pressures, e.g. pillar bulkhead compressive loads.
LT = denotes an internally generated load acting in the predominantly transverse direction as a consequence of applied forces and pressures, e.g. transverse deck compressive loads.
QV = denotes a shear force due to local load considerations acting in the predominantly vertical direction.
QT = denotes a shear force due to local load considerations acting in the predominantly transverse direction.
σ = denotes a direct stress to apply as a consequence of hull girder bending.
τ = denotes a direct shear stress to apply as a consequence of hull girder shear forces.

Dimensions

B = breadth, in metres, of an area of supported plate or dimension of a structural member. B is always measured in the transverse direction.
S = length of an area of supported plating or dimension of a structural member. S is always measured in the longitudinal direction.
H = height of an area of supported plating or dimension of a structural member. H is always measured in the vertical direction.

Suffix is either of the following:

Lower case = to denote a local load value which was derived in accordance with Vol 1, Pt 5, Ch 3 Local Design Loads
Upper case = to denote a resultant load value that is applied to the structural item under consideration.

2.1.2 The symbols used in this Chapter for loads are given below:

Local load or pressure components

P w = shell envelope hydrodynamic pressure, see Vol 1, Pt 5, Ch 3, 3.3 Hydrostatic pressure on the shell plating, Ph
P bi = bottom impact pressure, see Vol 1, Pt 5, Ch 3, 4.2 Bottom impact pressure, IPbi
P bf = Bow flare or above waterline impact pressure, see Vol 1, Pt 5, Ch 3, 4.3 Bow flare and wave impact pressures, IPbf
P in = pressure on internal deck, see Vol 1, Pt 5, Ch 3, 5.3 Pressure on internal decks, Pin
P ra = pressure on ramps or lifts, see Vol 1, Pt 5, Ch 3, 6.2 Loads for ramps and lifts, Pra

Design loads and pressures for structural components

P BS = design pressure for bottom structure.
P SS = design pressure for side shell structure.
P DK = design pressure for deck structure.
P WD = design pressure for weather deck.
= design pressure for interior deck.
= design pressure for inner bottom.
P LB = design pressure for longitudinal bulkheads.
P FL = design pressure for bottom floors and transverses.
P DH = design pressure for deckhouse, bulwarks and superstructures plating.
P DT = design pressure for deep tank bulkheads.
P WT = design pressure for watertight bulkheads.
L PI = design load carried by pillars.
L PB = design load carried by pillar bulkheads.
P CD = design pressure to be applied to cargo decks.
F CD = design load due to discreet mass items to be applied to decks.
= design pressure for decks subject to impulsive loads.
= design pressure for deckhouse and superstructure windows.
QT DK = local shear force for deck plating.
QT FL = local shear force for floors.
QV BG = local shear force for bottom girders.

NOTE

[F] = denotes a force matrix, i.e. a group of forces which are applicable to the structural item under consideration.

2.1.3 Other symbols and definitions applicable to this Chapter are defined below or in the appropriate sub-Section:

  1. T and L R are defined in Vol 1, Pt 3, Ch 1, 5.2 Principal particulars

2.1.4 The units for pressures are in kN/m2 and the units for loads and forces are in kN. Stresses are in N/mm2. Positive loads and stresses are tensile, negative are compressive.

2.1.5 The design pressure, p, used in scantling formulae in Vol 1, Pt 7, Ch 3, 2 Structural resistance is to be taken as the appropriate pressure value defined in this Chapter.

2.1.6 For a direct calculation using finite element (FE) analysis, only loads and pressures with a load type letter of P, P or F are normally to be applied to the FE structural model. Load type letters σhg and τhg may need to be applied as global bending moments and shear forces, i.e. M D and Q D, depending on the extent of the FE structural model.

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