井架在风荷载作用下的可靠性分析

AN ANALYSIS ON TOWER DERRICK UNDER THE ACTION OF WIND LOAD

通过对克拉玛依油田地区多年气象资料的统计分析，求得年最大风速的概率分布。依此，对塔形井架在最大风荷载等两种工况下结构体系的可靠度进行计算。利用分枝限界法计算原理，结合启发式寻找技术，作为寻找主要失效模式的方法，采用Ｄｉｔｌｅｖｓｅｎ窄界限，对结构体系失效进行区间估算。并用ＪＣ法对井架在最大风荷作用下的整体抗倾覆进行了可靠度计算。经可靠性分析、计算，井架在两种工况下结构体系的可靠指标都达到了规定的要求；

Based on statistical analysis of late years' meteorological data in the Kelamayi oil field,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 reliability 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 overturned under the extreme wind load.