Analysis of Vehicle–Bridge Coupled Vibration and Driving Comfort of a PC Beam–Steel Box Arch Composite System for Autonomous Vehicles

To investigate the dynamic characteristics of a PC beam–steel box arch composite bridge when the number of loading lanes for autonomous vehicles changes, the vehicle–bridge coupling motion equation was derived and solved iteratively via the Newmark-β method. Joint simulation software based on ANSYS 17.0 and Easy Language was developed to analyze vehicle–bridge coupling and driving comfort. The results showed that the dynamic response is the largest under single-lane conditions, with suspected vehicle–bridge resonance. For multilane conditions, eccentricity is the main factor when the vehicle weight is low, whereas the vehicle weight dominates when it is large. The dynamic response is positively correlated with eccentricity and vehicle weight. With respect to the dynamic amplification factor (DAF), single-lane conditions yield high DAF values for the main beam, main arch, and boom, whereas the main pier has a greater DAF under multilane conditions. Driving comfort is best under single-lane conditions, followed by dual-lane conditions, and worst under three-lane conditions. Speed is the primary influencer of comfort under single-lane conditions, with comfort reduced at higher speeds. Under multilane conditions, both speed and eccentricity affect comfort, with speed being the dominant factor. The calculated impact coefficient significantly exceeds the standard values, suggesting that separate impact coefficients should be set for each load-bearing component. These findings, combined with driving comfort analysis, provide valuable references for the setting of speed limits and the design and maintenance of such bridges under autonomous vehicle loads.