Damage Mechanism and Health Diagnosis for Marine Structures

①海底管线在地震作用下的破坏机理研究。

      基于多点地震输入模型，结合海底悬跨管道振动台模型试验结果，提出三维地震输入下海底悬跨管道的动水作用力模型，并进行了考虑管材和土体等材料非线性、和几何非线性的有限元时程反应分析，研究了影响海底管道动力特性的影响因素。
Based on the proposed multi-support excitation model and the model test results on the underwater shaking table, a hydrodynamic force model of submarine pipeline was built under the three-dimensional (3D) seismic excitations. By taking consideration of nonlinear constitutional relationships of pipe steel and soil, and geometry nonlinearity, the time history analysis was carried out and the factors that affect the dynamic responses of the submarine pipeline were studied. 

           
地震作用下的动水作用力模型
Hydrodynamic Force Model of Submarine Pipeline under Seismic Excitations

②海底管线的腐蚀破坏机理研究。

      根据数值分析结果提出如下适用于相邻双点腐蚀的相互作用准则；基于全截面塑性状态假设和管道材料理想弹塑性假设，推导了任意腐蚀形状的无限长腐蚀缺陷管道在内压－轴力－弯矩联合作用下的极限承载力的广义解。
According to the numerical simulations of the corroded pipelines, the interaction criterion of the neighboring two-pit corrosion was developed. Based on the plasticity assumption of the whole cross-section and the ideal elastoplasticity assumption of the pipe material, the generalized solution of limit load-carrying capacity for the infinite distance pipeline with corrosive defects was obtained in the case of the combination loads of the internal pressures, axial forces and the bending moments.

           
多点腐蚀相互作用分析模型和计算结果
Interaction Model of the Multi-pit Corrosion and Numerical Results of the Submarine Pipelines

③海底管线健康诊断的理论和方法研究。

      基于动力观测数据，建立了悬跨海底管线状态识别的统计模式识别方法，解决了实际运行中未知海底管线结构状态的问题。提取了环境荷载作用下海底管线的损伤敏感特征，发展了适用于在线监测的海底管线损伤识别方法。
The novel algorithm of the statistical pattern recognition with the dynamic measurements, which identifies the structural states in the real operation, was proposed for free spanning submarine pipeline, The damage-sensitive features of the submarine pipelines under the environmental loads was extracted, and the on-line algorithm of the damage identification was built.

           
海底管线状态和损伤识别
Condition and Damage Identification of the Free Spanning Submarine Pipelines

④海洋平台健康诊断研究。

      采用时频联合分析技术，对动态测试信号进行处理，确定导管架平台的基频、阻尼比和振型，得到结构的基本“指纹”。
The fundamental frequency, damping ratio and mode shape of the offshore jacket platform was identified by using of the jointly time-frequency analysis technique. The “finger printer” was obtained to monitor the structural state of the offshore platform.

           
海洋平台的“指纹”识别
Signature Analysis of the Offshore Platform