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
To aid in providing adequate resistance to the overturning moment by the
berthing load, the soil resistance above bedrock contributes to stabilizing
moment. For commonly adopted marine piling type, i.e. driven steel tubular
piles with reinforced concrete infill, driven piles can at most be founded on
top of rockhead surface. In case the rockhead level is shallow, then the
little soil cover may result in insufficient lateral resistance to the berthing
load.
3. Why are high and narrow beams not desirable in concrete piers?
(P2)
Based on past experience in other countries (Carl A. Thoresen (1988)),
high and narrow beams after several years of construction showed signs of
serious deterioration at the bottom of the beams. However, the
deterioration of pier slabs was not significant when compared with that of
the deep beams. The main reason to account for this is due to the close
proximity of the deep beams to the sea level. To avoid these problems,
either beamless slab or wide with shallow beams are normally designed.
4. Shall a layer of wearing course or additional thickness be designed
on the surface of piers? (P2)
In the design of piers, consideration should be given to the effect of
wearing action caused by passengers, other traffics and even sometimes
vehicles. In maritime environment, the durability and integrity of concrete is
detrimental to the servicing life of piers because it acts an essential barrier
to chloride attack. However, in view of these gradual wear and tear
generated by the loading traffic, some forms of surface protection should
be provided on top of pier surface like wearing course or additional
increase in concrete cover.
5. In mooring of vessels, wire ropes or fibre ropes are commonly
used for tying the vessels to mooring system. It is not recommended
to use them together in mooring. Why?
Mooring lines are provided by vessel while the shore provides the mooring
points.
Wire ropes provide a more rigid mooring system than fibre ropes. When a
high degree elastically is required, fibre ropes would be a better choice.
The mixed usage of wire ropes and fibre ropes is not recommended
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