Dynamic characteristic analysis of continuous rigid-frame bridges with short piers considering different pile-soil interaction models

Taking a long-span continuous rigid-frame bridge with short piers as a case study, finite element models were developed in MIDAS Civil to account for both the presence and absence of pile-soil interaction. A comparative analysis was performed to evaluate the influence of pile-soil interaction on the dynamic characteristics of the structure. The results indicate that pile-soil interaction exerts a considerable influence on the vibration modes and natural frequencies of the bridge, with its impact being particularly significant for lower-order vibration mode frequencies. The directly embedded foundation model tends to overestimate the overall stiffness of the bridge, neglecting the flexibility effects of the pile group foundation. The equivalent embedded foundation approach can effectively simulate pile-soil interaction within a reasonable parameter range. However, for bridges with unfavorable geological conditions, large spans, and complex structural forms, it is recommended to adopt the m-method for pile group simulation to obtain accurate and realistic dynamic characteristic results.