基于结构易损性理论的网壳失效模式分析初探

Failure scenarios analysis of single-layer latticed domes based on structural vulnerability theory

结构鲁棒性反映了结构系统抵抗外部环境干扰和内部不确定性因素影响而能保持稳定工作的能力。然而,对于结构鲁棒性评价指标尚未形成统一的理论方法和依据。易损性是鲁棒性的对立面,研究结构易损性可以从另一方面揭示结构缺乏鲁棒性的原因。Blockley等提出的结构易损性理论,通过分析不同初始破坏对结构几何拓扑关系的影响识别其薄弱部位。根据结构的节点连接性能将结构划分成不同层次的结构簇形成结构层级模型,利用结构层级模型找出结构的薄弱单元,从而确定结构内部存在的薄弱部位。将该理论应用于网壳结构倒塌模式分析,编制了相应的分析程序,以文献算例验证了分析程序的正确性。而后将易损性理论应用于星型网壳,说明基于易损性理论分析网壳等大跨空间结构倒塌模式的可行性。通过与地震作用下的倒塌模式相比较,表明结构易损性分析基本能够有效反映结构的最薄弱部位。失效模式的评价参数"相对损伤需求Dr"和"易损性指数φ"可以科学反映失效模式发生的容易性和造成后果的严重性,即相对损伤需求越小,发生该模式的可能性就越大于其他失效模式;易损性指数越大则表示该失效后果的越不成比例性。

The vulnerability theory was used to analyze the failure scenarios of single layer-latticed domes.A computer program was written to perform vulnerability analysis and its accuracy was verified with an example existing in the literature.The numerical failure scenarios analysis of a 24-members space frame dome was carried out.It is shown that the failure scenarios of long-span single layer-latticed dome can be obtained by the structural vulnerability analysis.The real failure scenario of the 24-members space frame dome subjected to earthquake motion was compared with the result of vulnerability analysis,indicating an effective way to know the weakness of the structure.The damage demand and the vulnerability index are two variables in the evaluation of failure scenarios.The damage demand is the measure of the effort required to damage a member and the vulnerability index indicates the ＂disproportionateness＂ of the damage consequence.