Structural Design and Response in Collision and Grounding

• Improved modeling of longitudinal extent ofdamage including the effect of transverse websand transverse bulkheads.• Application and comparison of models in caseswhere the struck ship has forward speed.• Application of models to other designs andassessment of damage length, beam and depthscalability with struck ship principalcharacteristics.• Struck ship design-parameter sensitivityanalysis.• Probabilistic analysis using scenario descriptionsdiscussed in the next section of this paper.• Modeling and application of a deformablestriking ship bow.6 COLLISION AND GROUNDING DATATwo basic types of data are required to support the goalsof this panel:1. Data for developing pdfs for grounding and collisionscenarios.2. Data for grounding and collision model validation,particularly for double hull damage.6.1 COLLISION AND GROUNDING SCENARIOSAs illustrated in Figure 2, probabilistic descriptions ofgrounding and collision scenarios are required to developprobabilistic descriptions of grounding and collisiondamage.The following data are required to define groundingscenarios:• Bottom or obstacle description• Depth of water• Grounding ship displacement, trim, draftand speed• Location of the obstacle relative to the ship'scenterlineA longer list is required for collision:• Striking ship• Speed• Displacement• Draft• Bow height• Bow shape• Collision angle• Strike location• Struck ship• Speed• DisplacementThe pdfs for these variables are not independent. Possiblerelationships for the collision variables are illustrated inFigure 28. Given the struck ship design and requirement:1. Since specific struck ships trade in specific ports onspecific routes, it is expected that they will encountera related subset or distribution of other ships (strikingships) that may not be a distribution representing allships in worldwide trade.2. A specific struck ship with known designcharacteristics in a specific trade will also haverelated distributions for draft, trim and speed. Note:this speed is the speed at the moment of the collision,and not necessarily operating speed.3. Given a specific type and tonnage of striking ship, itsother characteristics will also be related includingdisplacement/mass, bow half entrance angle, bowheight, draft, bow stiffness or structural design andspeed. Again, this is speed at the moment ofcollision, not operating speed.4. When two ships are maneuvering to avoid a collision(in-extremis), the resulting collision angle and strikelocation are expected to be related.Collision AngleStruck ShipDesign241Struck ShipSpeedStruck ShipTrimStruck ShipDraftStrike LocationStriking ShipTypeStriking ShipDwt3Striking ShipBow HEAStriking ShipBow HeightStriking ShipBow StiffnessStriking ShipLBP, B, DStriking ShipDisplacement,Mass,Draft,TrimStriking ShipSpeedFigure 28. Collision Scenario Variable RelationshipsThe data necessary to establish these relationships is verylimited. Collection and analysis of this data is ongoing.15