大跨度斜拉桥钢塔施工阶段振动控制

以南京长江第三大桥为例，进行了斜拉桥钢塔施工阶段的动力特性测试和振动控制．通过环境振动、人力激振和调谐质量阻尼器（TMD）激振的方式测试了代表性施工状态时，钢塔和塔吊结构体系的模态振型、频率和阻尼，结果表明，施工阶段南京三桥钢塔无控阻尼值高于国外（日本）同等规模钢塔阻尼平均值．依据实测的结构动力特性设计了TMD和调谐液体阻尼器（TLD）参数并实现了现场参数调节．为评价制振效果，分别对TMD和TLD工作与非工作状态（无控）时的结构阻尼进行了测试分析，表明安装TMD和TLD提高了结构的阻尼，具有良好的制振效果且满足设计的要求．

Vibration Control of Steel Tower of Large Span Cable-Stayed Bridge Under Construction

Measurement and vibration control of under-constructed steal towers of a large span(cable-stayed) bridge,the 3rd Nanjing Bridge over Yangtze River which adopted steel towers first in mainland China,was carried out. Mode shapes,natural frequencies and damping ratios of the bridge steel tower with tower crane attached at representative erection states were measured through ambient vibration,free vibration of human beings excitation and tuned mass damper(TMD) excitation.It was shown that the tower damping ratio without control was higher than the average values of steel towers built abroad(eg.Japan).Based on the measurement results,parameters of TMD and tuned liquid damper(TLD) were designed and adjusted on site.To evaluate the control effectiveness,structural damping of bridge towers with/without TMD and TLD were measured and the results showed that the structural damping ratio was significantly increased after TMD and TLD were installed,indicating that the control devices were of good performance and able to meet the design requirements.