ssc - 419 supplemental commercial design guidance for fatigue ship ...

Structural Design of the Ship Hull Girderbe calculated by direct calculation, although the rules do not provide the procedure for thecalculation. For locations other than the deck and bottom, and for ships where A r d k is less than70 m 2 , m s is equal to 1.0.γ 0 = 1.40 – 0.2 α L 0.2 for 130 < L ≤ 305 m= 1.54 – 0.245 α 0.8 L 0.2 for L > 305 mwhereα =1.0 for deck structures0.93 for bottom structures0.86 for side shell and longitudinal bulkhead stiffeners0.80 for side frames, vertical stiffeners on longitudinal bulkhead and transversebulkheadsA r d k is defined in Section 5/6A.3.6.2 of the Rules. A r is the maximum value of a bowflare shapeparameter, A ri , calculated for the first 4 hull stations in the forebody. d k is a nominal half deckwidth based on the hull stations in the forebody.A ri = (b Ti /H i ) S [b j 2 + s j 2 ] 1/2 , j – 1, n n ≥ 4dk=40.2∑bTi1b ti and s i are illustrated in Figure 2.2.The long-term distribution parameter, γ, is the Weibull distribution shape parameter, andas can be seen from the foregoing, increases with the length of the ship and with the propensityfor bow flare slamming.The guides for fatigue strength assessment of tankers, bulk carriers and for containercarriers are similar. The tables of permissible stress range for classes of structural details as afunction of the long-term distribution parameter are identical. Between bulk carriers andcontainer carriers, the definition of γ 0 is the same except that the lower limit for length is 150meters for bulk carriers, compared to 130 meters for container carriers. The definition of m s issimilar between bulk carriers and container carriers, except the definition of the bow flareparameter is different between the two ship types. For tankers, the long-term distributionparameter, γ, is a function of length only, and that definition is different from that of bulk carriersand container carriers.2-14