Study on dynamic responses and impact factors of long span deck type CFST arch bridge under vehicle loads

The long span deck type concrete filled steel tube (CFST) arch bridge encounters considerable safety risks under intricate traffic loads because to its extensive span, elevated columns, and pronounced dynamic sensitivity.This study utilizes the Wujiang Bridge, the world's longest span at 504 m, to elucidate the significant impacts of vehicle velocity, eccentric loading, and boom rigidity on both the overall and local dynamic responses of the bridge, employing finite element modeling (MIDAS) and vehicle-bridge coupling dynamics analysis. The findings indicate that the standard impact coefficient significantly underrepresents the dynamic effect. The impact coefficient for the lateral displacement of the end column is 0.426, significantly exceeding the standard value of 0.05. The velocities of 20 m/s and 28 m/s represent the crucial points of dynamic response; eccentric loading considerably enhances the torque effect on arch ribs (difference of 0.236).The study underscores the deficiencies of current codes in assessing local components and presents urgent recommendations: enhance bridge deck maintenance standards to minimize irregularities, enforce vehicle speed segment control, reinforce the dynamic design of critical elements such as tall columns and short booms, and develop a multi-parameter collaborative optimization model to enhance life safety. The findings offer theoretical backing and practical direction for the meticulous design, specification modification, and secure operation and maintenance of long span arch bridges.