Seismic damage characteristics and vulnerability analysis of Tibetan earth-timber structure buildings in the Ms 6.8 earthquake in Tingri, Tibet, China

This paper is based on a field investigation conducted to document the seismic damage and failure mechanisms of traditional Tibetan earth-timber structures, following the Ms 6.8 Tingri earthquake in Tibet, China on 7 January 2025. Seismic damage data from comparable buildings in regions with similar or higher seismic intensity are compiled and analyzed to evaluate the seismic performance and vulnerability characteristics under strong ground motions. The results indicate that typical Tibetan earth-timber buildings are generally constructed without systematic seismic detailing, leading to relatively low structural integrity and lateral stiffness.

These structures are highly sensitive to seismic excitation and exhibit a pronounced threshold effect in damage probability with respect to peak ground acceleration (PGA). They display limited seismic resilience under low-intensity ground motions but are subjected to extremely high collapse risk under moderate-to-strong earthquakes. Owing to differences in wall materials, construction practices, timber frame mechanical behavior, and joint connections, the seismic performance of Tingri buildings is inferior to that of similar vernacular structures in Sichuan and Yunnan, with higher exceedance probabilities at the same PGA. The derived fragility model adequately captures the seismic response of unreinforced traditional buildings. The outcomes provide a scientific basis for seismic retrofitting, cultural heritage preservation, and regional seismic risk assessment, and offer a valuable reference for performance evaluation of similar structures within the Himalayan seismic belt.