DOI: 10.57237/j.cear.2026.01.002 ISSN: 2996-1491

Causal Analysis of the Jianzha Yellow River Grand Bridge Collapse Using a Hierarchical Fault Tree

Hou Wenyan, Zhao Fengxia, Guo Zhengting
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Based on the facts established in the official investigation report, this study applies a hierarchical qualitative fault tree analysis to reconstruct the structural failure, management-barrier failures, and casualty consequences of the August 22 major collapse of the temporary cable-stayed fastening system at the Jianzha Yellow River Grand Bridge on the Xining-Chengdu Railway. The results show that the distribution-beam splice simultaneously contained high-strength bolts with substandard mechanical properties and fabrication and installation defects. Their interaction substantially reduced the load-carrying capacity of the joint. The cable force during the second-stage tensioning of No. 4 fastening cable did not exceed the design control value and therefore represented a normal construction condition. Nevertheless, the maximum construction load over the entire erection cycle triggered failure of the already defective joint, which progressed through bolt shear, distribution-beam fracture, failure of the cable-stayed fastening system, and collapse of the arch rib. Material and detailing defects were thus the primary causes, whereas the peak construction load was a failure trigger rather than the root cause. Consecutive failures of procurement, incoming inspection, retesting, fabrication qualification, process inspection, and final acceptance barriers allowed the defects to escape detection. Inadequate control of personnel exposure, warning, and evacuation further increased the casualties. On the basis of these causal paths, this study proposes lifecycle risk controls covering source quality assurance for critical connectors, physical inspection of temporary steelwork, joint acceptance before tensioning, and casualty reduction during high-risk operations. The findings provide a reference for identifying and controlling construction risks in temporary load-bearing systems for long-span arch bridges.

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