Effects of moving vehicles and running lane on the dynamic response of a long-span floating suspension bridge

Long-span floating bridges are not as robust as bottom-fixed bridges under moving vehicle loads due to weaker foundation stiffness. Understanding the effect of vehicles on the vehicle-induced dynamic response is essential for structural and operational safety assessments. This paper developed a dynamic analysis framework for floating bridges under moving vehicles, including different running lanes. The effects of moving vehicle speed, weight, running lane, vehicle number, spacing in the fleet, and vehicle fleet arrangement on the dynamic response of the example floating suspension bridge were investigated. The primary research outcomes include the following: 1) The developed framework can efficiently compute the dynamic response of the example floating bridge under moving vehicles. Compared with the bottom-fixed bridge scheme, the floating bridge under the same moving vehicle has larger dynamic responses, especially the lateral vibration response of the girder. 2) The vertical response of the floating bridge is mainly affected by the vehicle weight. The offset distribution of vehicle running lanes exaggerates the lateral vibrations of the bridge, of which the magnitude is similar to the vertical response. 3) Increasing the vehicle spacing in the fleet and implementing two-way opposing fleet traffic can effectively reduce the vehicle-induced lateral vibrations of the long-span floating suspension bridge. The design of the floating bridge can benefit from a better understanding of its dynamic response under moving vehicles.