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

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Amended July 2011, see page 3 Rules for High Speed, Light Craft and Naval Surface Craft, January 2011Pt.3 Ch.3 Sec.5 – Page 27ss Rs-----s Rt 0 and k according to Table B1.B 200 Bending201 The general requirement for thickness of plating subject to lateral pressure is given by:C= actual stiffener spacing (m)= basic stiffener spacing (m)=2100 ( + L)--------------------------1000is not to be taken less than 0.5 or greater than 1.0.Table B1 Values of t 0 and kItem t 0 kBottom, bilge and side to loaded water line 4.0 0.03Shell plating Side above loaded water line 3.5 0.02Bottom aft in way of rudder, shaft brackets etc. 10.0 0.10Strength deck weather part forward of amidships 3.0 0.03Strength deck weather part aft of amidships 2.5 0.02Inner bottom 3.0 0.03Deck and inner bottomCar deck 4.0 0.03platingAccommodation deck 2.0 0.02Deck for cargo 4.0 0.03Superstructure and deckhouse decks 1.0 0.01Collision bulkhead 3.0 0.03Tank bulkhead 3.0 0.03Bulkhead plating Other watertight bulkheads 3.0 0.02Superstructure and deckhouse front 3.0 0.01Superstructure and deckhouse sides and aft 2.5 0.01Other structuresFoundations 3.0 0.08Structures not mentioned above 3.0 0ts Cp= ------------- (mm)σ= correction factor for aspect ratio (= s/l) of plate field and degree of fixation of plate edges given in TableB2.202 The thickness requirement for a plate field clamped along all edges and with an aspect ratio ≤ 0.5:t22.4s p= -------------------- (mm).σB 300 Slamming301 The bottom plating is to be strengthened according to the requirements given in 302 to 303.302 The thickness of the bottom plating is not to be less than:t=22.4k r s P----------------------------- sl(mm)σ slk r = correction factor for curved plates= 1 – 0.5 s r - r = radius of curvature in mP sl = as given in Ch.1 Sec.2DET NORSKE VERITAS AS
Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Amended July 2011, see page 3Pt.3 Ch.3 Sec.5 – Page 28σ sl = 200 f 1 (N/mm 2 ).303 Above the slamming area the thickness may be gradually reduced to the ordinary requirement at side.For craft with rise of floor, however, reduction will not be accepted below the bilge curvature or chine.Table B2 Values of CDegree of fixation of plate edges Aspect ratio < 0.5 Aspect ratio = 1.0σ l σ s σ x σ y σ l σ s σ x σ yClamped along all edges 500 342 75 250 310 310 130 130Longest edge clamped, shortest 500 0 75 250 425 0 140 200edge simply supportedσ l = stress at midpoint of longest edge.σ s = stress at midpoint of shortest edge.σ x = maximum field stress parallel to longest edge.= maximum field stress parallel to shortest edge.σ yC. StiffenersC 100 Bending101 The section modulus of longitudinals, beams, frames and other stiffeners subjected to lateral pressure isnot to be less than:Z=m l 2 sp--------------- ( cm 3 )σm = bending moment factor depending on degree of end constraints and type of loading, see also Sec. 6Table B2.The m-values are normally to be as given in Table C 1.The m-values may have to be increased after special consideration of rotation/deflection at supports or variationin lateral pressure.The m-values may be reduced, provided acceptable stress levels are demonstrated by direct calculations.102 The requirement in 101 is to be regarded as a requirement about an axis parallel to the plating. As anapproximation, the requirement for standard section modulus for stiffeners at an oblique angle with the platingmay be obtained if the formula in 101 is multiplied by the factor:α1-----------cosα= angle between the stiffener web plane and the plane perpendicular to the plating.For α-values less than 12° corrections are normally not necessary.103 When several members are equal, the section modulus requirement may be taken as the averagerequirement for each individual member in the group. However, the requirement for the group is not to be takenless than 90% of the largest individual requirement.104 Front stiffeners of superstructures and deckhouses are to be connected to deck at both ends with aconnection area not less than:0.07a = ----------lsp ( cm 2 )f 1Side and after end stiffeners in the lowest tier of erections are to have end connections.Table C1 Values of mItemmContinuous longitudinal members 85Non-continuous longitudinal members 100Transverse members 100Vertical members, ends fixed 100Vertical members, simply supported 135Bottom longitudinal members 85DET NORSKE VERITAS AS
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RULES DET NORSKE VERITAS (DNV) = STRUCTURES = - Boat Design Net

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