Levy型劲性支撑穹顶结构连续倒塌分析

Progressive Collapse Analysis of Levy Type Rigid Bracing Dome

劲性支撑穹顶结构在遭受意外冲击时,可能发生连续倒塌,造成财产损失,甚至人员伤亡,因此分析其连续倒塌性能十分必要。本文依据Levy型劲性支撑穹顶结构的特点,给出杆件阀值系数及其计算公式,提出连续倒塌判别准则及倒塌类型;基于响应差值的损伤系数,给出杆件重要性系数;依据杆件重要性系数对Levy型劲性支撑穹顶结构的杆件重要性进行计算并排序;基于连续倒塌判别准则和杆件重要性分析结果,提出连续倒塌分析方法和流程,分析结构的连续倒塌性能,矢跨比、初始预应力对连续倒塌性能的影响,给出劲性支撑穹顶结构抗连续倒塌的方法。研究表明:Levy型劲性支撑穹顶结构的连续倒塌类型分为无倒塌、局部倒塌和整体倒塌;结构外环杆重要性系数最大,其次是内环杆;外环杆、内环杆和节点发生破坏,结构将发生连续倒塌,其它杆件破坏结构不会发生倒塌;矢跨比越小、初始预应力越大,杆件的重要性越小;加强节点和环向杆件根数可提高结构的抗连续倒塌能力。

When Levy type rigid bracing dome is impacted by unexpected load,its structure may collapse continuously,resulting in property loss and casualties,therefore,it is necessary to analyze its progressive collapse performance.According to characteristics of rigid bracing dome,the threshold coefficients of members and its calculation formula were given,and the discriminant criteria and types of progressive collapse were proposed.Damage coefficient based on response difference was proposed,and importance coefficient of members was given.Member importance of levy type rigid bracing dome were analyzed and sorted based on importance coefficient of members.Based on the discriminant criteria of progressive collapse and the results of importance analysis of members,the method and process of progressive collapse analysis were proposed.Progressive collapse performance of structure was analyzed.The influence of both rise span ratio and initial prestress on the progressive collapse performance was discussed.The method of progressive collapse resistance against rigid bracing dome was proposed.The research showed that the progressive collapse types of levy type rigid bracing dome could be divided into non collapse,local collapse and overall collapse.The outer ring bar obtains the largest importance coefficient,followed by the inner ring bar.The smaller rise span ratio is or the larger the initial prestress,the smaller importance of the member will be.When the outer ring member,inner ring member or node is damaged,the structure will collapse continuously,while other members will not collapse.Strengthening the joints and ring members can improve resistance of structure against progressive collapse.