臺灣博碩士論文加值系統

近來隨著大跨度橋梁不斷增加、橋梁採用材輕質強更具氣動力效應的斷面
，使得橋梁對風的靈敏性大幅增加，而且橋梁振態耦合效應更容易發生。
為抑制橋梁受風擾動而產生過大的振幅，影響橋梁安全性及行車舒適性，
本文將使用調質阻尼器來減低橋梁的振幅，並探討大跨度橋梁裝置TMD後
受風影響之氣動力行為並分別考慮振態耦合與振態無耦合兩種情況，以數
值分析來預測橋梁在設置前後結構之動態位移反應。

在考慮振態耦合時，將以單一調質阻尼器包括垂直向、扭轉向TMD及雙TMD
作為分析模型，分別推導各模型的運動方程式與轉換函數，以散漫振動理
論求得橋梁裝置TMD後的動態位移反應值，分析時取結構垂直向基本振態
與扭轉向基本振態來參與結構位移反應。

本文中採用了簡支梁例題一、例題二與斜張橋例題，當考慮振態耦合與無
耦合兩種情況時，在不同模型時設置TMD橋梁制振折減率的比較。在垂直
向TMD制振效果並無明顯差別；但在扭轉向TMD則會有明顯差別，並可發現
TMD對橋梁的制振折減率與有效阻尼有關。雙TMD是可同時抑制垂直向與扭
轉向振動的裝置，其垂直向在低風速有效，當高風速時垂直向制振效果降
低時，在扭轉向則會有制振效果。此結果亦與結構受風引發氣動力勁度與
氣動力阻尼改變有關。

The number of long-span bridges has increased vastly during the
post decades .To reduce the bridge weight , lighter materials
and more slender sections are used in long-span bridges .Hence ,
the susceptibility of this type of bridges to wind excitation
becomes more significant , and the effect of aerodynamic
coupling on the structural respons? g also more important
.Because the large buffeting response could lower down the
safety and serviceability of the bridge , this dynamic response
should be controlledby some devices . Among these devices tuned
mass dampers have been installed in some structures and proven
to be effective .

In this study , an analytical model is presented to examine the
performance of tuned mass dampers for suppressing the buffeting
response of long-span bridges and the effect of aerodynamic
coupling on the bridge-TMD system is investigated. Three types
of tuned mass dampers are examined in this study , these are a
single TMD for controlling vertical response , a single TMD for
controlling torsional response and the double TMDs for
suppressing vertical and torsional response simultaneously . To
account for theaerodynamic coupling , the fundamental modes in
vertical and torsional directions are adopted in the
formulations . Based on the analytical model , the equations of
motion can be derived . then , the transfer functions and the
dynamic response can be calculated by using of the theory of
random vibration.

Three examples are used to examine the performance of TMDs , the
first two are a simple-supported beam with different flutter
derivatives and the third is a cable-stayed bridge . The results
show that the aerodynamic coupling is not significant for
suppressing vertical , but it is very important for suppressing
torsional response especially when the wind velocity approaches
the flutter velocity . The double TMD system is as effective as
a single TMD for suppressing vertical is as effective as a
single TMD for suppressing vertical response and also performs
well for suppressing torsional response at high wind velocity .