中文摘要：

目前，对突发性极端荷载作用下海洋平台结构整体倒塌的非线性动力过程研究较少．基于海洋平台结构非线性动力时程分析，研究平台结构由于初始破坏引起的动力放大效应，建立海洋平台局部桩柱失效的等效静力模型，采用瞬时加载法，对局部失效的平台模型进行非线性动力响应分析．分析结果表明：随着DCR（需求能力比）值的增加，失效点的竖向位移增加明显，当DCR值很大时，极端荷载可能造成失效结构响应特性发生改变；失效桩柱节点动力放大系数远大于非失效桩柱节点动力放大系数，当DCR=0．9时桩柱失效动力放大系数最大为2．156；随着DCR值的增加，失效节点动力放大系数增加明显，而非失效桩柱结构的动力放大系数基本上保持不变．

英文摘要：

At present, non-linear dynamic processes research on total collapse in offshore platform structure under sudden and extreme loads is not a common practice. Based on the analysis of nonlinear dynamic time-history in offshore platform, platform structure dynamic magnification effect caused by initial damage is researched. The equivalent static force model of local pile failure in platform is established; and non-linear dynamic response analysis is used in model of local failure platform by instantaneously applied load method. The results show that： With the DCR （demand-capacity ratios） value increasing, the vertical displacement of failure point increases significantly. When DCR value is very large, response characteristics of failure structure may be changed, which is caused by extreme load response. Dynamic magnification factor of failure pile node is much larger than that of the non-failure pile node. When the DCR is 0.9, the maximum dynamic magnification factor of pile failure is 2. 156. With the DCR value increasing, the dynamic magnification factor of failure node increases significantly, while dynamic magnification factor of non-failure pile structure remains unchanged basically.