| Author | Ueong, Yeong-sheng |
| Call Number | AIT Thesis no. ST-88-27 |
| Subject(s) | Bridges, Cable-stayed
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | The effect of cable deterioration and cable failure on the dynamic
characteristics of Rama IX cable-stayed bridge in Bangkok and Erskine
cable-stayed bridge in the United Kingdom is investigated. The analysis is
carried out in the frequency domain using the mode superposition method. The
two bridges are modelled as plane frame systems and the harmonic ground
acceleration in vertical direction is used as excitation. Second order effects
in towers and deck are disregarded and linear-elastic material behaviour is
assumed . Different cable failure scenarios are examined.
The analysis reveals that the Fourier amplitude spectrum changes
significantly in the frequency range covering the first mode while only small
changes on the higher modes could be observed. Among the eigenfrequencies, t he
first eigenfrequency decreases up to 2% due to failure of any of the cables
of Rama IX bridge and 30% in the case of Erskine bridge.
In a symmetric bridge subjected to symmetric loads, the antisymmetric
modes do not contribute to the dynamic response. Therefore , whenever
eigenfrequencies of antisymmetric modes are measured in the center of a
symmetrical bridge, a more detailed investigation should be performed, because
asymmetry is an indicator of deterioration.
Furthermore, ambient vibration measurements at midspan of Rama IX bridge
before the bridge was opened to traffic were carried out . The results show
that the first few flexural eigenfrequencies of the finite element model of
the bridge coincide very well with the measured ones.
Based on this investigation an engineer should be capable to judge to
what extent bridge deterioration can be monitored by dynamic vibration
measurements and where instruments shall be placed. |
| Year | 1988 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Wireland, Martin
|
| Examination Committee(s) | Gupta, Satyendra P. ; Sritawat Kitipornchai ;Panitan Lukkunaprasit
|
| Scholarship Donor(s) | The Government of Republic of China |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1988 |