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船体梁极限强度英文文献和中文翻译(5)

时间:2020-10-24 10:51来源:毕业论文
The yield stress of HST and mild steel is 315Mpa and 235 Mpa respectively. The scantlings of longitudinals are listed in table 5. Table 1 : Principal dimensions of 34,000 ton bulk carrier Length overa


The yield stress of HST and mild steel is 315Mpa and  235 Mpa respectively. The  scantlings  of longitudinals are listed in table 5. Table 1 : Principal dimensions of 34,000 ton bulk carrier Length overall    200.00m Length between perpendiculars  191.00m Breadth  23.50m Depth  14.90m Draft  10.68m Block coefficient  0.8619 Frame spacing  0.80m Table 2: The scantlings of longitudinals   Stiffener No Type  Dimensions (mm) Yield stress(Mpa) 1  Angle bar  350x100x12/17  315 2  Angle bar  300x90x13/17  315 3  Angle bar  250x90x12/16  235 4  Angle bar  250x90x10/15  315 5  Flat bar  200x20  235 6  Flat bar  120x11  235 7  Flat bar  220x11  235 8  T bar  180x12/100x16  235 9  T bar  150x12/100x16  235 For the  purpose  of  representing the actual damage scenario, the location and extent  of structural  damage should in principle be defined either by real information from the accident or by using statistical data from past casualties.  Fig. 4: cross section of 34,000 ton bulk carrier amidship Every accident is different. The  resulting  damage also varies. Accidents require many parameters  to  describe the damage a ship sustains after an  accident. A comprehensive description can easily fill a couple  of pages or more, even though not all of  the data is necessary for calculating hull girder strength. There exist some assumptions with regard to damage extents. In the ABS Guide(1995) for assessing  hull-girder residual strength, a grounding damage includes bottom girders attached to the damaged bottom shell to a certain depth; collision damage includes deck stringer plate and slope bulkhead plating  attached  to damaged side  shell plating  for a specified extent. Paik, et al.(1998)  define collision and grounding damages according to this ABS Guide. For  sensitivity studies, they analyzed 0.8 to 1.2 times the specified damage extents described in the ABS Guide. For simplicity, the following damage definitions, which are convenient for calculation but retain the main characteristics of accident damages, are given: For a grounding, it is assumed that the bottom shell and the attached  bottom longitudinals are lost.  No girders are assumed to  be damaged after  grounding. In this study, a broader range of bottom loss, up to 80% of ship breadth, to simulate minor to severe grounding damages are investigated. At the same time, the damaged bottom structures are studied  both symmetrically and asymmetrically. For each type, some cases are analyzed. The following Table 3 and 4 give the detail information on the damaged structure induced by grounding.
For a collision, it is assumed that the side shell and the attached longitudinals are lost. The damage starts from the deck at the side and extends downward. The  deck stringer  plate is also assumed to be  damaged. A broad range  of side  shell, ranging  from 5% to 40%  of ship depth, is considered.    With  regard to this bulk carrier, the deck stringer  plate with the breadth  of  1100mm is assumed to  be damaged. The following collision cases listed in Table 5 are analyzed: Table 3: Damage extent of bottom caused by the grounding symmetrically Case  Range of damaged bottom symmetrical about center line (b) Ratio of b to breadth (b/B) 1  2960 mm  0.126 2  7400 mm  0.315 3  14800 mm  0.629 4  18000 mm  0.766 Table 4: Damage extent of bottom caused by the grounding asymmetrically Case Range of damaged bottom from the bilge (b) Ratio of b to breadth(b/B) 1  2750 mm  0.117 2  4350 mm  0.185 3  6750 mm  2.87 4  10270 mm  0.437 Table 5: Damage extent of side caused by the collision    Case Range of damaged side from deck (d) Ratio of d to depth (d/D) 1  745 mm  0.05 2  1500 mm  0.1 3  3000 mm  0.2 4  4850 mm  0.325 5  5960 mm  0.4 The residual resistances of damaged ship hull girder are analyzed  both  in hogging and sagging condition when the damage scenarios listed in the Table 3 to Table 5 are considered. The part  of result  curves of moment—curvature and the corresponding curves  of central position of  cross section—curvature are presented in Fig. 5 to Fig. 8. The Fig. 9 to Fig. 10 show the relationship of the residual strength index, which is the ratio of ultimate strength of damaged hull girder to that of intact hull girder,  and the damage extent in hogging and sagging states.   Fig. 5: Moment—Curvature curve(grounding symmetrically, Hogging)  Fig.6: Central position—Curvature curve(grounding symmetrically, Hogging)  Fig. 7: Moment—Curvature curve(collision, Hogging)  Fig.8: Central position—Curvature curve(collision, Hogging) For the  purpose of residual strength assessment, the residual strength index is to be introduced, which is the ratio of ultimate strength of damaged hull girder to that of intact hull girder as following formula: ) () () (Intact MDamaged M RIF index strength residualuu=  The  Fig. 9  and 10 give  the relationship of residual strength index (RIF) and the damage range curve.  Fig. 10: Relationship between Residual Strength Index and Damage Extent due to Collision 船体梁极限强度英文文献和中文翻译(5):http://www.751com.cn/fanyi/lunwen_63528.html
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