| Offshore jacket platform is the most common structure of offshore oil exploiting and producting in our country.At present some achievements have been acquired on the study of offshore jacket platform structure system.But the most of them are the static dynamical analysis ,safety assessed and deterministic optimum design ,which are the single side study. Considering the fuzziness of constraint boundary and analyzing the structural reliability in the paper,a model of reliability 梑ased structural fuzzy optimum design of offshore jacket platforms is established According to the characteristics of offshore jacket platforms , the tolerance coefficient of the constraint boundary is determined with the fuzzy optimization method. The optimum level cutset 2*,which is the intersection of the fuzzy constraint set and fuzzy goal set ,is determined with bound search method,and the fuzzy optimum solutions of fuzzy optimization problem are obtained.The suizhong 36-1 centre offshore platfom and chengbei No. 11 ~ offshore platform which lies in the shengli oil field is designed with the reliability-based fuzzy optimum model , deterministic optimum model and frizzy optimum model Structural optimum subrutines are formed. Through the results of the reliability-based fuzzy optimum are compared with the deterministic optimum design results and fuzzy optimum design results,we know that the deterministic optimum design and fuzzy optimum design all can make the value of objective function much lower than tbrmer. But the two methods don抰 consider the structural reliability,which results in the reliability distribute of structure aren抰 reasonable and the whole reliability of structure reduce. The results of example show that the reliability-based fuzzy optimum design is stable and reliable,which provided a new idea and method fbr the large complicated stucture optimum design. |
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