Time-frequency domain analysis of the dynamic response for the deck arch bridge based on classical vehicle-bridge coupling theory

This paper focuses on the dynamic response problem after replacing the girder of the deck-arch bridge. Based on a simple vehicle-bridge coupled model, the load is simplified to a constant force moving at a constant speed by Midas software. The working conditions were considered that the vehicle weight was 63.8t, and the speed was 60km/h, 80km/h, and 100km/h. A finite element model of the bridge was established to calculate the dynamic response under vehicle load, then the result was performed domain and frequency domain analysis. The results show that the stiffness of the beam is softer than the arch. Under the same conditions, the dynamic response of the beam is more obvious than the vault position. The amplitude of the dynamic response in the key sections is concentrated in the range of 0Hz to 15Hz. The main frequency was around 1.6 Hz, 3.7 Hz, and 8.6Hz corresponding to the second, fifth, and eighth natural frequencies of the bridge. As the vehicle speed increases, the influence of the second-order frequency was gradually increased to the dynamic characteristic of the bridge. When the vehicle frequency was close to the natural frequency of the bridge, the phenomenon of resonance was easy to occur