10. OBoat Hire - RPEQ Design Report

3.3 Design Basis
3.3.1   Durability and Design Life
The design life of the piles are 25 years. Steel pile is encased in a 12mm thick HDPE liner that is
terminated 2000mm below the seabed to ensure corrosion protection for the Atmospheric zone
through to the embedded zone. For the remainder of the pile not covered by the HDPE liner, due
to the lack of oxygen below the seabed it is anticipated that the levels of corrosion will be negligible
however a sacrificial allowance of 2mm per face over the 25 year design life has been allowed for
(Pile Design and Construction Practice Sixth Edition, 2014, M. Tomlinson, J. Woodward, P509,
Section 10.4.2 – Steel Piles for Marine Structures).

It is proposed to utilise FRP (fibre reinforced polymer) bars to the concrete decks in lieu of
traditional steel reinforcement. As this product is not susceptible to corrosion, a minimum cover to
the exposed side can be reduced to 25mm (AS3600 - Table 4.10.3.2).

Refer to TJS Maintenance and Operations Manual for time until first maintenance for various
elements of proposed pontoon system.


3.3.2   Design Loadings and Criteria
A summary of the design loadings and criteria applicable to this pontoon is given below:

Design Service Life

25 years (piles)

25 years (pontoons)


Storm Surge and Tidal Flow

Design Ultimate tidal flow velocity                    1.0m/s (AS3962 – Clause 4.8.4.2)

Assumed Debris Loading                                 10 kN/m (AS4997 – Clause 5.6)



Waves

Horizontal Wave Load                                   2 kN/m (AS3962 - Clause 4.8.4.3)



Wind

Importance level 2 (AS1170.0 - Table 3.1)

Design average recurrence Interval 250 years (AS1170.0 - Table 3.1)

Region B (AS1170.2 - Fig. 3.1 (A))

Terrain Category 1.5 (AS1170.2 - Clause 4.2.1)

250-year ARI regional wind speed 53.0m/s (AS1170.2 – Table 3.1)




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