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The
Rama 6 bridge is the Thailand's longest steel truss bridge
crossing the Chao Phraya River located in Non Thaburi.
The bridge was destroyed by airplane bombing in 1942 during
the World War II. The bridge reconstruction was later
on completed in 1953. The bridge is the main rail route
connecting the central part to the southern part of Thailand.
The bridge is 442 meter long, 10 meter wide comprising
of 5 span trusses, 2 simple spans and 2 anchor spans that
support a suspended span through a pin and a link connection.
The
link connection of the suspended span is supposed to be
able to move freely as a so called "roller" per structural
design concept. However, the link was moved from the center
of the horizontal guide and become "locked" at one end
of the guide, which can not be moved freely as it should
be. As a result of this "locked" link, the bridge behavior
has been changed from its original design concept, which
may cause numerous problems in the future.
It
is necessary to 1) determine the cause of the link "locking"
at one end of the horizontal guide 2) reset the bridge
so that the link can move back to the center position
3) perform further study and evaluate the bridge safety.
To
achieve the objectives, IMMS had undertaken following;
| (1) |
A complete bridge inspection.
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| (2) |
A structural analysis. |
| (3) |
A residual stress determination
of the structure. (this was done to determine
the force and reaction of all supports). |
| (4) |
Structure monitoring on the
bridge movement. (this was done over a two
year period using GPS, tilt meter, etc). |
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(5) |
Bridge resetting. |
| (6) |
Non destructive testing of
fatigue prone and of load-carrying capacity
of critical members (the pin an the link connections).
Ultrasonic and Acoustic Emission ware the
Non destructive testing method being used. |
| (7) |
Dynamic magnification to evaluate
the impact effect of the train to the structure. |
| (8) |
Bridge capacity evaluation.
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