Multiscale Damage Evolution and Load-Transfer Mechanisms of a Millennium-Old Stone Arch Bridge: A Case Study of the Guanyin Bridge

Ancient stone arch bridges are a significant scientific challenge for cultural heritage preservation worldwide, with the core difficulty lying in the fact that, over the course of centuries, they have been subjected to damage from numerous unpredictable factors. Taking a millennium-old stone arch bridge as an example, this paper employs a comparative analysis of a load-damage model developed under multi-factor and multi-constraint conditions and a three-dimensional finite element simulation model—covering both global and local aspects—to reveal the energy transfer patterns of the bridge’s overall and local mortise-and-tenon structures, as well as the intrinsic characteristics of deformation and stress propagation. Research data indicate that, under the action of overall external loads, stress in stone arch bridges is primarily concentrated at the abutments; for individual mortise-and-tenon structures, the regions of maximum stress are concentrated at the abutments of the main arch rings on the north and south sides; the energy transfer pathways within both structures differ from theoretical calculations, and abrupt changes in local stress occur. The comprehensive analysis results are generally consistent with the on-site damage observed in the stone arch bridges. Multiple sets of samples collected from the damaged areas were subjected to microscopic testing and analysis, which further confirmed that long-term environmental erosion is also a contributing factor to the deterioration of stone arch bridges. This study conducted a detailed investigation ranging from theoretical modeling to finite element simulation and microscopic testing. The research models and data obtained will provide a scientific basis for the preservation of millennia-old cultural relics and offer strong support for preventive restoration efforts.