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
react with sulphates to form calcium sulphoaluminate and gypsum that
cause expansion and crack the concrete structure.
However, for marine concrete sulphate-resisting cement should not be
used because tricalcium aluminate has high affinity for chloride ions. This
is based on the possible reaction of chloride ions and tricalcium aluminate
to form calcium chloroaluminate hydrate as suggested by P. Kumar Mehta
(1991) and the reduction of which may increase the rate of chloride attack
to the concrete marine structure and result in faster corrosion of steel
reinforcement in marine structures.
10. What is heeling during vessel berthing?
When a vessel berths on a fender system at a pier, the point of contact of
the berthing ship may be above or below the centre of gravity of the ship.
During the berthing operation, some kinetic energy is dissipated in work
done to heel the ship i.e. the work done to bring the ship an angle of heel.
This energy is normally a small fraction of total berthing energy and
therefore it is normally not considered in design. However, designers
should pay attention to the possible hitting of the berthing structure by the
vessels in case the contact point is well above water level [19].
11. What is the difference in application of surface-protecting fenders
and energy-absorbing fenders? (F1)
Surface-protecting fenders are fenders that induce high reaction forces to
berthing structures for the energy absorbed while energy-absorbing
fenders are fenders which transmit low impact to berthing structures for the
energy absorbed (Carl A. Thoresen (1988)). In fact, the principal function of
fenders is to absorb the berthing energy and transmit a force to the
structures without damaging them. Therefore, in open berth structures, it is
desirable to use energy-absorbing fenders to reduce the loads acting on
the relatively flexible structures. On the other hand, for solid berth
structures the usage of surface-protecting fenders is adequate because
they are capable of taking up large berthing loads.
12. What is the difference between weight chain, shear chain and
tension chain in fender system? (F1)
The weight chain is used to sustain the weight of face and frontal panel.
Shear chain help protect the fender from damage while the fender is in
shear deformation and they are orientated at 20 - 30° to the horizontal.
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