Research For Direct Assessment Of Oil Tanker Based On HCSR And CSR-OT

With the frequent occurrence of shipwreck accidents,people are becoming more and more aware of the importance of ship structure safety and the urgency of finding a good solution.Born in this context,the Common Structural Rules(CSR),which has a great impact on the safety of ship structures,has been criticized because of its huge difference in the specification of oil tankers and bulk carriers.In order to solve this problem,and considering the requirements of IMO GBS,IACS has introduced the Harmonized Common Structural Rules for Bulk Carriers and Oil Tankers(HCSR)on the basis of the CSR.However,for the existing mature ship types,whether the HCSR can achieve or exceed the applicability of CSR still needs to be verified by a large number of applications of real ship.The main contents of this paper are as follows:(1)Based on the fourth strength theory,the yield strength analysis methods of HCSR are studied in depth,including the establishment of models,the deduction of corrosion thickness,the setting of loads,the selection of load cases,the application of boundary conditions and criteria,etc.By comparing and analyzing the relevant contents of the Common Structural Rules for Double Hull Oil Tankers(CSR-OT),the difference of yield strength analysis methods among them are summarized.Then,based on the coarse grid yield strength evaluation method,the detailed stress assessment method is studied,and the differences between the two refined mesh analysis models are discussed.(2)The structural stability theory is used as the technical background,and its stability and post buckling characteristics are analyzed respectively.Based on the application of finite element method in buckling analysis,the HCSR method for buckling assessment,the ultimate buckling state and evaluation criteria of hull plate are studied in detail,compared with the CSR-OT requirements for buckling evaluation.(3)Based on the HCSR,the calculation of yield and buckling strength of a 114 thousand ton Tonna oil tanker which meets the requirements of CSR-OT is carried out.The results are compared with the results calculated according to CSR-OT,and the structural area of the target ship which does not meet the requirements of the HCSR is strengthened.The yield,buckling and detailed stress assessment of the strengthened structure are also made.The rationality of the strengthening method is analyzed,and the influence of the HCSR on the original mature ship form is discussed,and reference is provided for its strengthening method to meet the HCSR.