Analysis of the damper diseases for controlling the longitudinal displacement between the tower and main girder of a long-span suspension bridge

Abstract

Taking a suspension bridge across Yangtze River as an engineering background, the disease mechanism and treatment measures of longitudinal damper of this bridge were analyzed in detail based on field observation and monitoring data. Firstly, the paper describes the disease of the dampers in detail, e.g., bolt fracture, pin slip-out and ear plate fracture. Afterwards, the cause of the damper disease is analyzed based on the measured transverse and vertical relative displacements between the tower and main girder. On that basis, the improvement design and replacement of the new dampers are carried out. Finally, according to the longitudinal relative displacement between the tower and main girder recorded by the bridge health monitoring system, the movement condition of the main girder before and after the damper is compared and analyzed. Results show that the maximum transverse and vertical relative displacements between the tower and main girder can reach 25mm and 60mm. The large relative displacement between the tower and main girder makes the stress on the two side ears of the longitudinal damper unbalanced, which leads to the diseases such as pin slip-out and ear plate failure of the damper. Improvement of damper includes structural measures and strength measures, mainly including optimization of baffle, ear plate and pin shaft, etc. The improved and optimized damper is in good service condition.