A Self-Learning Manual - Institution of Engineers Mauritius

A Self-Learning Manual
Mastering Different Fields of Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU
22. What is shock transmission unit in bridges? (BS5)
Shock transmission unit is basically a device connecting separate
structural units. It is characterized by its ability to transmit short-term impact
forces between connecting structures while permitting long-term
movements between the structures.
If two separate structures are linked together to resist dynamic loads, it is
very difficult to connect them structurally with due allowance for long-term
movements due to temperature variation and shrinkage effect [54]. Instead,
large forces would be generated between the structures. However, with the
use of shock transmission unit, it can cater for short-term transient loads
while allowing long-term movements with negligible resistance. It benefits
the bridge structures by acting as a temporary link between the structures
to share and transfer the transient loads.
Fig. Shock transmission unit.
23. Should raking piles of a bridge abutment be placed under an
embankment? (BS6)
For a bridge abutment to be supported on raking piles with different
orientations, the movement between the ground and the pile group is
difficult to predict. For instance, if some of the raking piles of the bridge
abutment are extended beneath an embankment, then the settlement of
embankment behind the abutment may cause the raking piles to
experience severe bending moment and damage the piles as
recommended by Dr. Edmund C Hambly (1979).
24. Sometimes the side of concrete bridges is observed to turn black
in colour. What is the reason for this phenomenon?
In some cases, it may be due to the accumulation of dust and dirt. However,
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