自升式平台整体结构的三维系统可靠性分析

Three-dimensional System Reliability Research of Overall Structure for Jack-up Platform

为使自升式平台整体结构三维系统可靠性计算模型更加贴近实际结构,建立基于空间刚架结构和空间薄壁结构两种系统可靠性分析模型.以三维梁元模拟空间刚架结构,以杂交梁元和加筋板格元模拟空间薄壁结构,并推导加筋板格元的修正刚度矩阵和反向结点力向量,弥补了计算反向结点力向量时采用等剪应力矩形元替代加筋板格元的不足,最后运用改进的分支限界法搜索主要失效路径并结合PNET法计算系统失效概率,通过实例对自存和作业等工况下平台系统可靠性进行计算,对比两种系统可靠性模型的优缺点,给出工程设计建议.

For the accurate calculation of three-dimensional system reliability of overall structure for jack-up platform, two models based on space frame structure and thin-walled space structure are established. Space frame structure model is established by three-dimension beam, and thin-walled space structure model is established by adopting hybrid girder element and SP element. Formulae of reduced member stiffness matrix and opposite sign of equivalent nodal force are educed, to make up accuracy of calculation of opposite sign of equivalent nodal force. The significant failure modes are identified by using advanced branch-and-bound method and the structural system reliability is evaluated by PNET method. Take the calculation of system reliability under different conditions as the example, engineering design proposals are proposed by compared the results between two models.