漂浮体系悬索桥拟静态纵向运动特性及其控制

营运状况下漂浮体系悬索桥加劲梁纵向运动产生的过大累积行程会引起伸缩缝和塔梁纵向阻尼器等连接构件的性能退化和疲劳损坏.探索加劲梁纵向运动过大累积行程的成因,并找出降低累积行程的控制措施是确保悬索桥健康运营的关键.首先,以江阴长江大桥实测位移时程数据为基础,对不同频谱特性的位移成分进行分解,并统计了不同位移成分的循环次数和...

Characteristics of quasi-static longitudinal motion and its mitigation for floating-type suspension bridges

The excessive cumulative longitudinal movement stroke of stiffening girders of floating-type suspension bridges under operation condition will lead to performance degradation and fatigue damage of connecting components such as expansion joints and longitudinal dampers between tower and girders. The key to ensure the normal and safe operation of suspension bridge is to explore the causes of excessive cumulative longitudinal movement stroke of stiffening girders and find out the control measures to reduce them. Firstly,based on the measured displacement time history data of Jiangyin Yangtze River Bridge,the displacement components with different spectral characteristics were decomposed,and the cycle numbers and cumulative stroke of different displacement components were calculated. The results show that the quasi-static displacement components contribute most of the cumulative stroke. Then,based on the finite element model,the cause of quasi-static longitudinal motion was analyzed,and the time history of equivalent vertical concentrated force was obtained by curve fitting. Finally,based on the time history of equivalent vertical concentrated force,the control measures of quasi-static longitudinal motion were studied. Results show that the longitudinal displacement of stiffening girder in suspension bridge can be divided into three different components according to the causes and spectrum characteristics:temperature change induced elongation and shortening deformation,quasi-static longitudinal motion and the longitudinal resonance. The quasistatic longitudinal motion contributes more than 70% of cumulative stroke,thus the longitudinal motion control can’t ignore its influence. The generation of quasi-static longitudinal motion of the stiffening girder is related to the unbalanced vertical concentrated force brought by the vehicle load. The unbalanced vertical concentrated force moves on the bridge deck for the whole length of the stiffening girder and completes a complete longitudinal motion cycle. This mechanism is the fundamental reason for the generation of quasi-static motion. Based on the generation mechanism of quasi-static longitudinal motion,the equivalent vertical concentrated force can be obtained by curve fitting,which can effectively reconstruct decomposed quasi-static longitudinal displacement. The equivalent vertical concentrated force can be used to conveniently evaluate the control performance of various control devices on quasi-static longitudinal motion. The combination of velocity-dependent damper and friction damper can effectively suppress the quasi-static longitudinal motion of stiffening girders.