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The
Rama IX is the World's longest single plane cable-stayed
bridge crossing the Chao Phraya River connecting the eastern
and western sides of Bangkok. The bridge was opened in
1987. The total length of the bridge is 782 meters, comprising
of a 450 meter main center span and two 166 meter side
spans.
The
eastern side concrete pier of the side span was found
to have a visible continuous vertical cracks and secondary
cracks running branching off from the vertical cracks.
To determine the crack depth and overall structural integrity
of the bridge, IMMS had provided several types of Non
Destructive Testing (NDT). Impact echo method was used
to determine the concrete soundness and crack depth, and
Half-cell potential method was also used to evaluate the
corrosion on reinforcing steel rebars of the pile caps.
In
2002, IMMS was assigned by The Expressway and Rapid
Transit Authority of Thailand (ETA) to evaluate
the overall structural integrity of the RAMA IX
bridge as following;
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Evaluate tension forces in cables,
total of 68. |
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Evaluate dynamic properties
of 16 tune mass dampers. |
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Determine cable's damping ratio
and verify damping properties of cable dampers.
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Perform Finite Element Analysis
(FEM) of the bridge structure by making use
of the parameters measured in the field. Loading
assigned in FEM model was in compliance with
AASHTO and DIN code requirements. |
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Calculate factors of safety
of the cables due to section loss |
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Calculate allowable elongation
of cables by structural compatibility and
stability analysis. |
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