新型自复位不锈钢管中管混凝土-钢组合导管架海洋平台结构冰振性能与设计优化研究

Jacket offshore platform structures are complex, large, and expensive. Their surrounding ocean environment is complicated and harsh.The collapse accidents of ocean platform happened many times in recent years because of sea ice load in Bohai sea, and caused huge economic losses and casualties.Therefore,the safety of ocean platform is very important.Self -centering structure is a newly-developed structural system in recent years and able to reduce the seismic effect and structural damage. It can be used after earthquake with less repair or even without repair. This project proposes a novel self-centering corrosion-resistant concrete-filled stainless double steel tubular and steel hybrid jacket ocean platform structure system, in which prestressed stainless steel tension rod technology is used from outer to inner. The “outer” is that the prestressed stainless steel tension rods are used in outside jacket offshore platform to vibration reduction, the “inner” is that the jacket is concrete-filled stainless steel tubular filled with stainless steel tension rod. Theoretical analysis together with experimental study will be used to investigate (1) the self-centering pretressed concrete-filled stainless double steel tubular jacket’s construction for offshore platform in marine environment,(2) to study design method of novel concrete-filled stainless double steel tubular and steel hybrid self-centering ocean platform based on prestressed tension rods subjected to sea ice load, (3) to study ice-induced mechanical behaviors of the new systems,(4)to optimize this self-centering structure system, and (5) to propose design methods of self-centering corrosion-resistant concrete-filled stainless double steel tubular and steel hybrid jacket ocean platform structure system. It is anticipated that the results of this project will promote the application of the new offshore platform structure, and provide technical support and security for China's offshore oil and gas resources’ sustained, steady development in shallow sea. In summary, this project is important and significant in practical applications.

导管架海洋平台体积庞大、构造复杂、造价昂贵，所处海洋环境十分恶劣。近年来渤海湾发生过多次海洋平台被海冰推倒事故，造成了重大的经济损失，因此海洋平台的安全防护至关重要。预应力自复位结构是最近几年兴起的结构形式，可减少结构的破坏，使其震后稍加修复或不需修复即可投入使用。本项目提出新型自复位耐腐蚀不锈钢管中管混凝土-钢组合导管架海洋平台结构体系，将采用理论分析和试验研究相结合的方法，“由外到内”采用预应力技术，“由外”为在平台体外采用预应力拉杆进行减振，“到内”为导管采用预应力不锈钢管中管混凝土。研究预应力不锈钢管中管混凝土导管，研究基于预应力拉杆的抗冰海洋平台设计方法，研究该新型平台冰振受力性能，对该体系进行优化，建立自复位不锈钢管中管混凝土-钢组合导管架平台设计方法。本课题的研究将对新建导管架海洋平台提出了新的思路，为我国浅海海洋油气资源开发的持续稳步发展提供技术支撑，具有重要实际意义。

冰荷载作为渤海地区导管架海洋平台主要控制荷载，有效控制海洋平台冰激振动对保证平台安全性和耐久性至关重要。增强海洋平台刚度或直接减小所受冰力，均是控制平台冰激振动的有效途径。基于该研究思路，提出了不锈钢钢管混凝土-钢组合导管架海洋平台结构体系（简称组合海洋平台），重点从不锈钢-混凝土-碳素钢中空夹层钢管混凝土（Stainless Steel-Concrete-Carbon Steel (SCC) Double-Skin Tube (DST)，简称SCC DST）导管腿的受剪、轴压、抗冲击性能、组合节点和组合海洋平台抗冰激振动几个方面进行研究，具体内容如下：.（1）为研究组合海洋平台的抗冰性能，首先从构件层面研究SCC DST导管腿的抗冰剪切性能，着重研究外钢管材料、空心率、剪跨比和混凝土强度对试件抗剪承载力的影响。在参数分析的基础上，根据蔡绍怀提出的极限平衡计算方法，考虑剪跨比对SCC DST导管腿抗剪承载力的影响，得到抗剪计算公式，为SCC DST导管腿在海洋平台中的应用提供理论支持。.（2）通过分析空心率、混凝土强度和径厚比等参数对轴压承载力的影响，得到了试件轴压承载力与空心率、混凝土强度和径厚比有关；空心率与径厚比的减小和混凝土强度的提高，试件承载力得到了提高。.（3）研究SCC DST导管腿在横向冲击荷载下的动力响应，主要研究冲击后的受力和破坏模态，结果表明SCC DST导管腿在横向冲击荷载作用下塑性变形发展充分，抗冲击性能较好；不锈钢导管腿在单次冲击下承受的能量最高，承受的冲击次数最多。.（4）为解决新型海洋平台桩腿截面形式改变后，下部SCC DST导管腿与上部钢管间非等径异截面的连接问题，设计了过渡件节点、隔板加劲肋节点和法兰节点三种新型节点型式并优化。加强后的过渡件节点和隔板加劲肋节点承载力都显著提升，其中法兰节点承载力最高，隔板加劲肋节点延性最好。.（5）对海洋平台冰荷载确定、结构选型和材料选择、静力设计和冰力设计等方面进行综合考虑分析，提出了组合海洋平台设计方法。基于该方法，设计了某组合海洋平台，验证本文所提设计方法的可行性和有效性。