Analysis Of Ultimate Strength And Sensitivity For Bulk Carriers Based On IACS Common Rules

In the modern ship construction design research realm, people pay more and more attention to the ultimate strength of ship hull girders. This is because that the perfect construction design is closely neted the true strength store of the ship girders. However, in order to understand the actual strength store of ship hull girders, we must have a right assessment of the ultimate strength of ship hull girders.Recently, classification societies started to develop rules for the structural design of bulk carriers and double hull tankers several years ago which after adoption by all member societies of the IACS will be mandatory for all classification societies.The goal of the Common Structural Rules is eliminating the competition for minimised scantling dimensions and steel weight to the detriment of ships' safety between the ship classification societies. The members in the societies can share the experience by implementing the same rules.And the rules aim at satisfying the requirement of building stronger, more durable and suitable ship.This thesis used along the relationship of the ship section element stree-strain by Common Structural Rules for bulk carriers(JBP).The Rules enter into force on 1st April 2006.A program is developed by using the Progressive callopse analysis method to calculate the ultimate strength of bulk carriers.Progressive callopse analysis method is also named Smith method. Firstly, it needs to separate the girder hull into many elements-pulled one and pushed one. Secondly, when the ship is in hogging or sagging, you should assume one curvature value so you can get the moment value of every element at this curvature. And then you may add up all the moment of every element. Thirdly, you must judge whether the moment is the ultimate moment. If not, increase the curvature, and redo the above steps until get the ultimate strength. These procedures can be realized by one circulation. In every step, the curve of stress-strain is modified, so the result is more precise. On base of the above research contents, a program is developed in FORTRAN language by using this simplified method to analyse the ultimate strength of ship hull girders. In comparison with the results from some famous experts of International Ship&Offshore Structures Congress. This simplified method has engineering accuracy and can be used in the pre-phase of design. Finally, this thesis discuss the sensitivity about several parameters which influence the ultimate bending moment of bulk carriers.