| Summary: | 碩士 === 淡江大學 === 土木工程學系 === 85 === Title of Thesis: Total
Page:111 Section Model Experiments of Cable Stayed
BridgesName of Institute: Graduate Institute of Civil
Engineering Program, Tamkang
UniversityGraduate Date: June, 1997 Degree
Conferred: MasterName of Student: Bo-Sheng Wang
Adviser: Dr. Chii-Ming Cheng 王柏盛
鄭啟明 博士 Dr.
Yuh-Yi Lin
林堉溢 博士Abstract: Suspended bridges, especially cable
stayed bridges, have been built widely around the world
nowadays. Because it is more flexible than other bridges, the
dynamic behaviors caused by wind have to be carefully studied.
The most significant aerodynamic phenomenon for cable stayed
bridges are flutter instability and buffeting effects. Several
factors influence these aerodynamic phenomenon. Besides
structural features ( mass, stiffness, damping), flutter
derivatives and wind force coefficients are the most important
ones. In this research project, section model was used
to study the effects of bridge deck shape and wind attack angle
on the flutter derivatives and wind force coefficients. Three
deck geometry: plate section, box section and one similar to
Kao-Pin-Hsi bridge, were used while the wind attack angle were
varied from -6 to +6 at 2 interval. Experimental results
indicate that the plate girder type, which possess asymmetric
shape and prone to flow separation, has higher value of force
coefficients and most unstable flutter derivatives. On the other
hand, the box girder type has a better symmetric shape and
fairing to weaken flow separation, therefore, exhibits lower
value of force coefficients and more stable flutter derivatives.
As for the wind attack angle, negative attack angle tends to
cause aerodynamic instability, positive attack angle will
stabilize bridge.The flutter derivatives and force coefficients
were then applied to estimate flutter velocity and buffeting
response of a cable stayed bridge with similar structural
characteristics as Kao-Ping-Hsi bridge. Results indicate that
considering the mode coupled flutter derivatives will reduce
critical velocity and increase bridge dynamic responses.
Keywords: suspended bridges, attack angle, flutter derivatives,
force coefficient.
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