RULES DET NORSKE VERITAS (DNV) = STRUCTURES = - Boat Design Net

Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Amended July 2011, see page 3Pt.3 Ch.3 Sec.5 – Page 26SECTION 5PLATING AND STIFFENERSA. GeneralA 100 Introduction101 In this section the general requirements for plate thicknesses and local strength of panels of aluminiumalloy are given.102 Buckling strength requirements are related to longitudinal hull girder stresses. Panels subjected to othercompressive, shear or biaxial stresses will be specially considered.Table A1 Allowable bending stressesItem Plate Stiffener(N/mm 2 )Bottom, slamming load 200 f 1 180 f 1Bottom, sea load 180 f 1 160 f 1Side 180 f 1 160 f 1Deck 180 f 1 160 f 1Flat cross structure, slamming load 200 f 1 180 f 1Flat cross structure, sea load 180 f 1 160 f 1Bulkhead, collision 180 f 1 160 f 1Superstructure/deckhouse front 160 f 1 140 f 1Superstructure/deckhouse side/deck 180 f 1 160 f 1Bulkhead, watertight 220 f 1 200 f 1Tank bulkhead 180 f 1 160 f 1A 200 Definitions201 Symbols:t = rule thickness of plating in mmZ = rule section modulus of stiffener in cm 3s = stiffener spacing in m, measured along the platingl = stiffener span in m, measured along the top flange of the member.The depth of stiffener on crossing panel may be deducted when deciding the span.For curved stiffeners l may be taken as the chord lengthp = design pressure in kN/m 2 as given in Ch.1 Sec.2σ = nominal allowable bending stress in N/mm 2 due to lateral pressure (see Table A1)f 1 = see Sec.l A202τ = nominal allowable shear stress in N/mm 2 .A 300 Allowable stresses301 Maximum allowable bending stresses in plates and stiffeners are to be according to Table A1.B. PlatingB 100 Minimum thicknesses101 The thickness of structures is in general not to be less than:tt 0 + kL= ----------------fs---- (mm)s Rf =σ fσ-------- f240= yield stress in N/mm 2 at 0.2% offset for unwelded alloy.σ f is not to be taken greater than 70% of the ultimate tensile strengthDET NORSKE VERITAS AS