A novel quantitative evaluation method for seismic safety of ancient Chinese timber arch lounge bridges

Timber arch lounge bridges, as an important architectural heritage, face challenges such as insufficient research on seismic performance, incomplete evaluation indicators, and uncertain evaluation methods. Existing seismic evaluation methods are primarily qualitative analyses based on modern bridges, which fail to fully consider the structural characteristics and mechanical behaviors of timber arch lounge bridges. This study proposes a novel quantitative evaluation framework that systematically integrates site conditions, seismic-resistant construction, material deterioration, and structural responses to enable rapid and accurate seismic safety evaluations. The improved analytic hierarchy process (IAHP) is developed by incorporating component importance analysis (CIA), which considers multi-directional seismic actions. The Wenxing Bridge is taken as a case study to demonstrate the evaluation process. The results show that the king columns, penta-segment oblique members, and tri-segment oblique members are not only vulnerable components under seismic actions, but their failure also significantly impact s the structural integrity. The seismic safety of Wenxing Bridge under the design basis earthquake action is Grade II, indicating moderate damage. The proposed method exhibits generalizability and can provide a scientific basis for seismic evaluation and preventive conservation of ancient timber arch lounge bridges.