Dynamic Behaviors and Vibration Control of Steel Tower of Long Span Cable-Stayed Bridges under Construction

摘要

Using the 3rd Nanjing Bridge over Yangtze River as an example, the dynamic characteristics of steel towers of the cable-stayed bridge under construction were monitored and Tuned Mass Dampers (TMD) and Tuned Liquid Dampers (TLD) were applied for suppressing the tower vibration due to wind load. Mode shapes, natural frequencies and damping of representative erection states of towers with tower crane attached were calculated based on measurements of ambient vibration or vibration excited by human beings or TMD. To evaluate the effectiveness of TMD and TLD in the tower vibration control, structural damping of bridge towers was analyzed. It is shown that the inherent structural damping of the steel tower is higher than the average values of damping of steel towers constructed in Japan, and the structural damping is increased with the installation of TMD or TLD, which indicates that the control devices have good performance and can meet the design requirements.