基于改进模态推覆法的导管架平台弹塑性抗震性能

Elastic-Plastic Seismic Performance for Jacket Platform Based on Improved Modal Pushover Method

针对强震下海洋导管架平台的弹塑性失效问题,提出一种基于性能设计的海洋导管架平台改进模态推覆抗震分析法,获得强震下平台结构的弹塑性抗震性能及其失效模式,解决强震下海洋导管架平台的弹塑性抗震性能评估难题.通过对比分析设防和罕遇烈度8度地震下平台结构弹塑性地震响应的差异性,探讨平台结构的参振振型、振型形状向量以及地震动不确定性对平台结构弹塑性抗震性能的影响.研究结果表明:高阶振型和振型形状向量对导管架平台弹塑性抗震性能的影响较大,需考虑前9阶或9阶以上的模态振型及振型形状向量变化的影响;设防和罕遇烈度8度地震下,平台结构弹塑性抗震薄弱环节均位于导管架顶部,需重点关注;具有相同峰值加速度的不同地震时程下的平台结构地震响应表现出明显的离散性和差异性,建议采用改进模态推覆法评估强震下平台结构弹塑性抗震性能.

In connection with the elastic-plastic failure problem of offshore jacket platform subjected to a powerful earthquake,an improved modal pushover method based on performance design is proposed.The elastic-plastic seismic performance and failure modes of the jacket platform are obtained to solve the problem of elastic-plastic performance evaluation of the offshore jacket platform in strong earthquakes.The elastic-plastic seismic responses of the platform in 8-degree seismic fortification and rare intensity are calculated by using different methods,and the differences between these responses are compared.Besides,the influences of combined modes,mode shape vectors,and uncertainties of seismic are discussed.The results show that the high-order vibration modes and mode shape vectors have a great influence on the elastic-plastic seismic performance of the platform.The first 9 or higher order modes and mode shape vectors should be adopted.The seismic-resistant weak links are located at the top of the platform in 8-degree seismic fortification and rare intensity,which should be paid more attention to.The seismic responses of the platform show significant differences and discreteness in different seismic activities,which have the same peak seismic acceleration.The improved modal pushover method is suggested to be used to evaluate the elastic-plastic seismic performance of jacket platform.