中文摘要：

利用Plackett Copula分别构造波高、风速及流速的二维及三维概率分布,并用单变量设计法、条件分布众值及均值法及三维联合重现期法获得三个荷载变量的不同组合,计算导管架平台的基底剪力,利用三维概率分布估计变量组合的联合重现期。对结果比较分析可知,单变量设计法所得剪力值远远大于其他方法所得剪力值,其独立分布所得重现期远远大于联合变量的重现期。条件分布所得剪力值的大小取决于主变量的选择。计算表明,波高对剪力的影响最大,当以波高为主值利用条件分布进行计算时,其剪力值最大。以风速、流速为主值的工况,所得平台基底剪力小。利用三维Plackett Copula构造三维联合分布进行平台设计参数的估计,考虑了变量之间的相关性,与传统的单变量法相比,所得设计环境条件数值减小,将使平台建设成本降低,适用于边际油田的开发。

英文摘要：

The bivariate and trivariate distributions of wave height, wind velocity and current velocity are constructed with Plackett Copula, respectively. Different load combinations for these three variables are obtained in three ways： single variable design method, conditional distribution method（including both mode and mean value cases） and the trivariate joint distribution method. The base shearing force of a jacket platform is calculated and the joint return periods of different combinations are estimated. Results show that the computed base shear forces by the first method are obviously larger than others, and the corresponding return periods are larger than the joint return period. The results by the second method change with the choice of the predominant variable. Wave height contributes much more than both wind velocity and current velocity to the product of the platform base shear force. In the cases of considering current velocity or wind velocity as a predominant factor, the platform base shear is relatively smaller. The trivariate distribution constructed with Plackett Copula, considering the correlations among variables, can be used to estimate the design parameters of ocean environmental conditions. Compared with the single variable design method, the estimated design parameters can decrease and lead to lower platform construction cost, which will be suitable for the exploitation of a marginal oil field.