Coupling Effect and Structural Response of Ancient Chinese Timber Structures with High-Platform

High-platform timber structures represent a typical structural form in ancient Chinese architecture, where the platform and the upper timber structure constitute a mechanically coupled system with interacting mechanical properties and response behaviors. However, a systematic understanding of their global coupling mechanism and its impact on structural response remains unclear. This study investigates a representative high-platform timber structure, i.e., Xi’an Bell Tower, to analyze the static and dynamic response characteristics of the platform–superstructure system using in situ dynamic testing and finite element simulation. The results indicate that the simulated first two natural frequencies align well with in situ measurements, validating the model’s rationality. The global coupling effect alters the system’s mass and stiffness distribution, leading to an overall lengthening of the structural natural periods. Structural self-weight is identified as the dominant factor inducing vertical deformation under serviceability conditions, with significant deformation observed at the platform’s edges and corners. Under lateral loads, deformations concentrate in the second story of the timber superstructure, with seismic actions exerting a more pronounced influence than wind loads. Under rare earthquake conditions, the maximum inter-story drift ratio reaches 1/70. Local tensile stresses at the joints, architrave ends, and the Dou-Gong layer exceed the timber’s tensile strength parallel to the grain, identifying these components as the weak links in the structure’s seismic performance.