Mechanism and Influencing Factors of Central Longitudinal Cracking in the Small Wild Goose Pagoda

The Small Wild Goose Pagoda in Xi’an is a Tang-dynasty square multi-eave brick pagoda that has repeatedly experienced longitudinal cracking during historical earthquakes. To investigate the mechanism of recurrent central longitudinal cracking, a three-dimensional numerical model of the reconstructed fifteen-story pagoda was established as the baseline. Modal analyses were performed for the reconstructed fifteen-story baseline model and four comparative geometric configurations to characterize their global dynamic properties. Nonlinear static pushover analyses and comparative geometric models were then used to examine the effects of loading direction, arched openings, pagoda height, slenderness, and the present thirteen-story configuration. The results show that the response is governed mainly by tensile damage. Under east–west loading, damage initiates near the arched openings and propagates upward to form a central longitudinal cracking path broadly consistent with the historical damage pattern. The arched openings control crack initiation by interrupting wall continuity, whereas height and slenderness mainly affect crack propagation. The present thirteen-story configuration changes the upper-level damage distribution but does not alter the basic central longitudinal cracking path. These results provide a mechanical explanation for the recurrent longitudinal cracking of the Small Wild Goose Pagoda and a reference for the assessment and conservation of similar masonry pagodas.