【作者】 王瑜；

【导师】 杨树耕；

【作者基本信息】 天津大学 ， 船舶与海洋结构物设计制造， 2009， 硕士

【摘要】 桁架腿以其透空式结构,有效降低了结构重量和波流载荷,成为自升式平台最为常见的桩腿结构型式。对现有平台结构分析表明,桁架腿的拓扑型式、结构形状和构件尺寸设计对平台的结构响应有重要影响。因此,优化技术必将成为改进桩腿结构设计的重要工具。本文研究了桁架腿结构选型优化设计的理论与数值方法,建立了复杂环境下桁架腿结构的多约束条件的设计模型,并深入研究了在复杂海洋环境作用下的桁架腿自升式平台结构响应的分析技术以及大规模优化设计问题的模型和求解方法。首先,本文对自存工况下的某自升式平台进行了静力分析,并根据规范对桁架腿结构进行了校核。结果表明,构件的强度和稳定性均满足要求,而且有较大储备,对桁架腿结构进行优化设计是可行且必要的。在静力分析基础上,本文利用APDL语言建立了K型、X型和inv-K型三种型式桁架腿参数化设计模型,并根据规范给出了强度、刚度、稳定性等约束在ANSYS优化中的合理描述形式。优化过程中,针对两层设计变量耦合困难的问题,采用了分层优化方法。为验证优化模型和方法的可靠性,本文对某自升式平台桁架腿进行了选型优化设计。从优化结果来看,可以得出最优的桩腿型式和尺寸,而且位移响应也相对合理。综上表明,本文所采用的优化模型和方法简单实用,优化效果显著,为自升式平台桁架腿的概念设计提供了一种有效工具。更多还原

【Abstract】 As the light weight and low hydrodynamic loads obtained from its openwork structure, Truss-type leg is applied to more and more jack-up units. Analysis of existing jack-up units indicates that the topology pattern, configuration dimensions and cross section dimensions of components have an important influence on the structure’s stiffness and intensity. Therefore, the application of advanced design optimization technology can effectively raise the design quality.The theoretical and numerical methods of structural design optimization for truss-type leg are studied in this thesis. A design optimization model of truss-type leg with multiple constraints is established. The numerical calculation methods of static analysis of structural response under the action of complex ocean environment are presented, and the formulation and solving methods of layout, shape and size optimization for large scale structures are studied.Static analysis of an existing jack-up unit under survival load case is performed. According to Rules for Building and Classing Mobile Offshore Drilling Units, the stress and displacement of the components satisfied the requirements and have a long way to reach the limit of the codes, which means design optimization for truss-type leg is feasible and necessary.The parameter models of K-bracing, X-bracing and inv-K bracing truss-type legs are established. Constraints such as stress and displacement are given rational descriptions in ANSYS. The optimization process is divided into two steps to avoid the coupling problem of two kinds of variables. To validate the feasibility of the optimization, a example is performed. The results indicate that the best design can be obtained and the structure response is also relatively smaller after optimization. Therefore, it is convinced that models and methods of optimum lectotype in this thesis are effective and can be a useful tool in the concept design of the jack-up truss-type leg.更多还原