Ultimate Strength and Chain-Reaction Failure of Hangers in Tied-Arch Bridges
Ultimate Strength and Chain-Reaction Failure of Hangers in Tied-Arch Bridges
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DOI：
10.1080/10168664.2020.1775537
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发表时间：
2020-07-23
影响因子：
1.1
通讯作者：
Miyachi, Kazuhiro
中科院分区：
文献类型：
--
作者：
Nakamura, Shunichi;Miyachi, Kazuhiro
这项研究的动机是最近倒塌的一个分支拱肋系拱桥。一辆重型卡车过桥时，吊架接连断裂。本文对系拱桥的极限强度、吊索断裂原因及吊索链式破坏模拟进行了研究。非线性有限元分析表明，该桥梁模型具有足够的极限强度。吊架布置方式对极限强度有显著影响。支吊架分布均匀的模型具有较高的极限强度，支吊架张力平衡良好。钢丝的腐蚀疲劳会导致悬挂绳断裂。二次弯曲应力、不同的安全系数、质量控制不合理的吊架张力、移动车辆引起的冲击因素以及其他车辆的影响都会进一步放大应力幅值。由于锈蚀钢索的疲劳强度显著降低，估计的应力幅值可能导致吊架断裂。当吊架断裂时，死载荷和活载荷都是脉冲工作，它们被等效的静载荷所取代。载荷被重新分配到破碎悬挂器旁边的悬挂器上，导致悬挂器发生连锁反应失效。这种模拟方法阐明了桥梁坍塌的机理。
This study was motivated by the recent collapse of a tied-arch bridge with branched arch ribs. Hangers were successively broken when a heavy lorry crossed the bridge. In this article, the ultimate strength of tied-arch bridges, causes of hanger rope breakage and simulation of chain-reaction failure of hangers are studied for tied-arch bridges. Nonlinear finite element method analysis has clarified that this bridge model has sufficient ultimate strength. The hanger arrangement significantly affect the ultimate strength. The model with uniformly distributed hangers has higher ultimate strength and the hanger tensions are well balanced. Corrosion fatigue of wires could cause hanger rope breakage. The stress amplitude would be further amplified by secondary bending stresses, different safety factors, improper hanger tensions due to poor quality control, impact factors induced by moving vehicles, and effects of other vehicles. As the fatigue strength of corroded strands is significantly decreased, the estimated stress amplitude could cause hanger breakage. When a hanger breaks, the dead and live loads work impulsively, which are replaced by the equivalent static loads. The load is redistributed to the hanger next to the broken hanger, which induces the chain-reaction failure of hangers. This simulation method clarifies the mechanism of the bridge collapse.