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在突发事件的直接影响下,结构的局部构件可能首先发生初始破坏并进一步导致结构的连续性倒塌。与框架结构或承重墙体系相比,大型公共建筑中普遍采用的桁架体系具有冗余度较低的特点,为提高其结构鲁棒性,必须在详细分析基础上采用不同的设计策略。该文以钢屋架体系为例,通过连续性倒塌过程的数值分析,研究了内力重分布过程、动力效应和主要破坏模式等问题;根据局部杆件失效后的结构特性,归纳出转动铰机制、滑移面机制和长压杆机制等三种基本的局部内力重分布机制;结合简化数学模型的理论分析,阐述了敏感构件和关键构件的概念,为该类结构的安全性评价提供了一种简便的尺度。
Under the direct influence of emergencies, the local components of the structure may first damage and further lead to the collapse of the continuity of the structure. Compared with the frame structure or load-bearing wall system, the truss system commonly used in large-scale public buildings has the characteristics of low redundancy. To improve the structural robustness, different design strategies must be adopted based on detailed analysis. Taking steel truss system as an example, the problems of internal force redistribution process, dynamic effect and main failure mode are studied through the numerical analysis of continuous collapse process. According to the structural characteristics after the failure of partial bars, the rotating hinge mechanism is concluded, Sliding surface mechanism and long-bar mechanism of the three basic local internal force redistribution mechanism; combined with simplified mathematical model of the theoretical analysis of the sensitive components and key components of the concept for the safety evaluation of such structures provides a Simple scale.