关键词: 井架, 风荷载, 可靠性, 结构体系, 安全裕度, 主要失效模式

Abstract: Based on statistical analysis of late years' meteorological data in the Kelamayi oil fie1d, the probability distribution and statistical characteristic of recent years' extreme wind velocity were acquired.Reliability of the tower derrick was analyzed for derrick subjected to extreme wind load and operating load in which the rcliability of resisting overturn was estimated by using JC method.The computer program was revised to consider non-normal distribution of the basic variables and the relations of those variables.The dominant failure modes were determined by branch-bound method combining with some newly developed improving measures.The failure probability of structural systems were estimated by using Ditlevsen's bounds based on the dominant failure modes and revision of the upper bound by discarded failure paths.The result shown that the reliability indexes of derrick itself came up to the stipulated requirements, but the weakest point was the overturning stability.If the anchoring force were greater than the calculated value, the derrick would not be ovcrturned under the extreme wind load.

Key words: derrick, wind loading, reliability, structure system, safety margin, dominant mode of failure