基于振动响应的导管架平台极限承载能力分析

为评估到达一定服役期限的导管架平台结构安全性能,提出基于振动响应的平台时变极限承载能力分析方法。以东海某气田导管架平台为对象开展振动监测研究,采集不同海况下平台上部组块的加速度响应,通过随机减量法对平台振动响应数据进行特征函数提取,分别采用时序分析法和复指数法对预处理数据进行动力学参数识别。借助有限元分析建立不同损伤状态下平台固有频率数据库,通过与模态参数识别数据对比识别出平台结构健康状态。应用时域分析法进行平台非线性动力学分析,并结合极限承载能力评估准则建立动力极限承载能力分析方法。结果表明,基于振动监测分析结果的平台修正模型能较准确地反映在役平台结构健康状态,可实现平台的结构抗力的精确评估,得到不同服役期导管架平台结构时变抗力变化规律。

Ultimate bearing capacity analysis of jacket platforms based on vibration response

In order to assess the safety of the jacket platform which has served for many years, ultimate bearing capacity analysis method based on vibration monitoring was proposed. Vibration monitoring was carried out at CEP jacket platform of a gas field in the East China Sea, and the acceleration responses of top side module were collected under different sea conditions. The characteristic function of platform vibration response was extracted using random decrement technique. Furthermore, time series analysis and complex exponential method were used to identify the dynamic parameters for the characteristic function. The frequency databases of different damage modes were established by finite element analysis of the platform under various damaged conditions. Health conditions of platform structure were recognized by comparing identification results of modal parameter with frequency database. Nonlinear dynamics analysis was conducted by time domain analysis method, and dynamic ultimate bearing capacity analysis method was established. Field application results show that the updating model based on vibration monitoring can reflect real health status of platform structure, and the structural resistance can be assessed accurately by conducting the ultimate bearing capacity analysis of model updating method, which leads to time-varying structural resistance of platform.