AbstractIn recent years, the π-shape structure, that is, two pile shafts supporting a reinforced concrete beam and its superstructure, is increasingly used for bridge foundations. Considering the construction quality and the requirement of settlement tolerance, the pile lengths of the π-shape structure are sometimes different when passive or active. However, the effect of the unequal pile lengths on the dynamic characteristics of the π-shape structure has not been investigated. Therefore, this paper analyzes the dynamic response of the π-shape structure with unequal pile lengths. A beam–unequal length piles–soil coupled vibrating system is established in the frequency domain considering both pile–beam–pile propagation and pile–soil–pile interaction. In order to account for the pile–soil–pile interaction, a fictitious soil pile model is employed to compensate for the length difference between the piles. The developed model and the analytical results are verified through comparison with the results of rigorous finite-element analysis and a model test. The verified model and its corresponding solutions are then utilized to conduct a comprehensive parametric study. Some conclusions derived from this study can extend the application of the π-shape structure in engineering practice.