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.6 – Page 34of the edge exceeds:0.06 t t (m)t t = thickness in mm of tripping bracket.The area of the stiffening is not to be less than:10 l t (cm 2 )l t = length in m of free edge.The tripping brackets are to have a smooth transition to adjoining longitudinals or stiffeners exposed to largelongitudinal stresses.Table B4 Spacing between tripping bracketsGirder typeS T (m)Bottom and deck transverses0.02 bStringers and vertical webs in generalfmaximum 6Longitudinal girders in generalLongitudinal girders in bottom and strength deck for L > 50m within 0.5 L amidships0.014 bStringers and vertical webs in tanks and machinery spacesfmaximum 4Vertical webs supporting single bottom girders and transversesIf the web of a strength member forms an angle with the perpendicular to the ship’s side of more than 10°,S T is not to exceed 0.007 b f .b f = flange breadth in mmS = distance between transverse girders in m.B 600 Girder web stiffeners601 The web plate of transverse and vertical girders are to be stiffened where:h w > 75 t w (mm)t w = web thickness in mm,with stiffeners of maximum spacing:s = 60 t w (mm)within 20% of the span from each end of the girder and where high shear stresses.Elsewhere stiffeners are required when:h w > 90 t w (mm)with stiffeners of maximum spacing:s = 90 t w (mm)For girders supporting other girders, the end requirements may have to be applied all over the span.602 Stiffeners are to be fitted along free edges of the openings parallel to the vertical and horizontal axis ofthe opening. Stiffeners may be omitted in one direction if the shortest axis is less than 400 mm and in bothdirections if length of both axes is less than 300 mm. Edge reinforcement may be used as an alternative tostiffeners.DET NORSKE VERITAS AS