Numerical Analysis on Buffeting Performance of a Long-Span Four-Tower Suspension Bridge Using the FEM Model

The multi-tower suspension bridge (MTSB), which is a considerable choice for the cross-river and even cross-sea bridges, has attracted intensive attentions by researchers in recent years. However, the static and dynamic performance of the MTSB becomes more complicated due to its super long spans and the multiple middle towers. The wind-induced vibration becomes the critical issue when constructs the MTSBs due to their low rigidity. In this work, a finite element model (FEM) of a MTSB with four towers and three spans is presented. Several major parameters such as the stiffness of the main girder and the middle towers, the sag-to-span ratios, the self-excited forces, and the spectral model of turbulence are selected to investigate their effects on buffeting performance of the MTSB. Results show that the rigid main girder can decrease the buffeting displacements in lateral and torsional directions, while the vertical buffeting displacement significantly decreases with the increasing stiffness of middle towers. In addition, the buffeting displacements of the main girder increase with the decreasing sag-to-span ratio. Besides, it can be concluded that the self-excited forces should be considered and the turbulent power spectrum should be carefully chosen in analyzing buffeting responses of the MTSB.