- 學位論文
自錨式吊拉組合橋地震反應特性之探討
An Investigation into the Seismic Response Characteristics of Self-Anchored Cable-Stayed Suspension Bridge
摘要
自錨式吊拉組合橋是一種全新的結構體系，由主梁、橋塔、主纜、斜拉索及垂直吊索所組合而成的新式橋梁，兼具了自錨式懸索橋和斜張橋的許多優點。相較於自錨式懸索橋，具有較高的抗風穩定性；又相較於自錨式斜張橋，則具有較低的橋塔高度，所以在大跨度橋梁中具有很大的發展空間。 本文針對自錨式吊拉組合橋的地震反應特性進行分析模型建立與分析探討比較，文中利用ANSYS套裝軟體，以反應譜法及歷時法，進行在堅硬、普通、軟弱及台北盆地等四種不同地質條件的自錨式吊拉組合橋於順橋向及垂直向之地震反應分析，藉以瞭解位處四種不同地質條件的自錨式吊拉組合橋之地震反應特性；另外，亦進行具有不同子結構勁度或不同幾何形狀的自錨式吊拉組合橋之地震反應分析，藉以瞭解不同子結構勁度與不同幾何形狀的自錨式吊拉組合橋之地震反應特性。研究成果顯示，斜拉索子結構勁度變化對順橋向地震反應之影響最大；主纜子結構勁度變化對垂直向地震反應之影響最大。另外幾何形狀變化中，以矢跨比變化對地震反應影響最大。 最後以歷時方法分析探討裝設金屬耗能減震器對自錨式吊拉組合橋地震反應之影響比較，以及子結構勁度變化及幾何形狀變化對此種橋梁順橋向地震反應之影響。研究成果顯示，金屬耗能減震器在地震時可以消耗大量的地震能量，減少主梁及橋塔的變位，亦可有效減少斜拉索及主纜的內力之情形發生。
並列摘要
A self-anchored cable-stayed suspension bridge, which includes stayed cables and possesses, combines merits of both a self-anchored suspension bridge and a cable-stayed suspension bridge, which forms a totally renewed structure mechanism. When compared to a self-anchored suspension bridge, this type of bridge gives better wind-resisting stabilities; and when compared to a cable-stayed suspension bridge, this type of bridge requires a lower tower height and does not require huge anchor bases. Hence, it is more adaptable to complex and weak geological conditions, and is therefore expected to have a more extensive developing room in the category of large-span bridges. This research has established the numerical models and performed the detailed analysis to investigate the characteristics of earthquake response of self-anchored cable-stayed suspension bridge. By using ANSYS program and both of response spectrum analysis method and time history analysis method, this research performs the longitudinal and vertical earthquake response analysis in four different geological conditions in order to realize the characteristics of earthquake response of self-anchored cable-stayed suspension bridge in different geological condition. In addition, the influences of geometric changes and the changes in the stiffness of substructures on the earthquake response of self-anchored cable-stayed suspension bridge are also studied. The analysis results indicate that the change in the stiffness of slant cables has the largest influence on the longitudinal earthquake response, and the change in the stiffness of main cables has the largest influence on the vertical earthquake response. Moreover, the change of rise-span ratio has the largest effect in influences of geometric changes. Finally, through time history analysis, the earthquake response of cable-stayed suspension bridge, after the installation of the metal dampers, has been analyzed and studied in this research. In addition, the influences of geometric changes and the changes in the stiffness of substructures on the earthquake response of this bridge are also studied. As a result, the device of the metal dampers can effectively reduce the energy of earthquake, joint displacement of main girder and tower, internal force of slant cables and main cables, etc.