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.10 – Page 52σ aσ c = -----ηK J − 0 = according to Fig.1h w = height of web in mm.b f=3.5 lσ------------ c(mm)K J – 0---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---E 300 Web and flange buckling301 The σ el -value required for the web buckling mode may be taken as:σ el 3.8E t w----- 2 =( N ⁄ mm 2 )h wt w , h w = web thickness and height in mm.302 The ideal elastic buckling stress of flange of angle and tee stiffeners may be calculated from thefollowing formula:= flange thickness in mm= flange width in mm for angles, half the flange width for T-sections.303 The critical buckling stress σ c found from A102 is not to be less than as given in 202.t fb fGuidance note:σ el 0.38 E t f---- 2 =( N ⁄ mm 2 )b f— Web thickness, see plating with stiffener in direction of compression stress, D103.— Flange width from web:140b f < t f----------------- (mm)σ------------ cK J – 0σ c = according to 202K J − 0 = according to Fig.1---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---F. Stiffeners Perpendicular to Direction of CompressionF 100 Moment of inertia of stiffeners101 For stiffeners supporting plating subject to compressive stresses perpendicular to the stiffener directionthe moment of inertia of the stiffener section (including effective plate flange) is not to be less than:lst= span in m of stiffener= spacing in m of stiffeners= plate thickness in mmI=0.81σ aσ el l 4 s-------------------------------- ( cm 4 )tσ el =σ------------ cK J – 0DET NORSKE VERITAS AS