Safety Improvements of Fijian Jetties. Authors Tim Morrison MWH Christchurch, NZ Nigel Beatson MWH Nelson, NZ Mandar Panvelkar MWH Sydney

Transcription

1 Safety Improvements of Fijian Jetties Authors Tim Morrison MWH Christchurch, NZ Nigel Beatson MWH Nelson, NZ Mandar Panvelkar MWH Sydney

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3 Poor construction materials and practices and lack of maintenance left many jetties in an unsafe condition

4 Outline Fijian Government response The process of assessment categorisation emergency repair Detailed assessment Repair Replacement Measures to improve safety

5 2012 Fijian Government recognised the need to a significant shift in the management of Roads Bridges Jetties RoRo jetties River landings The infrastructure 10,000km of roads 1,000 bridges 44 jetties The FRA was formed in 2013 to replace the old Department of National Roads

6 The Jetties and river landings

7 Inspection planning logistics

8 Cultural issues Sevusevu Presentation of gift of kava Ask permission to visit the island Source of valuable anecdotal information Cyclone effects Construction history Local preferences Shipping frequency Kava ceremony to conclude

9 Types of jetties Small river jetties Piled suspended deck

10 Infilled sheet piled

11 Infilled sheet piled

12 RoRo operation

13 What did we find? Corrosion to the soffit of suspended slabs Impact damage to piles and beams

14 Severe corrosion of primary beam reinforcing

15 Sheet piled jetties with no rear sheet piled wall following Tropical Cyclone Winston

16 Settlement of fill in infilled sheet piled type structures, bollard damage Fender damage

17 Severe corrosion on ladders on dolphins General corrosion

18 Things we couldn t explain Discontinuities in piles

19 The inspections done, we started a series of Emergency repairs Closures of jetties to vehicles Prioritisation of repair and replacement Multi Criteria Aanalysis Detailed investigation Scoping and Feasibility report followed by Concept report Consultation local residents shipping companies Maritime Safety Authority of Fiji (MSAF) Government Shipping Services itaukei Land Trust Board Ministry of Works, Transport & Public Utilities Divisional Commissioner Provincial Council The Department of Environment The Ministry of Fisheries Reporting to FRA

20 The significant safety issues were Concrete corrosion Severe beneath suspended structures Not evident from above Corroded strand in U beams beneath Heavily used Jetty

21 Unrepaired concrete damage Jetties located in exposed marine environment Berthing damage almost inevitable No regular inspection and maintenance regime Jetty missing pile and next pile not attached to beam

22 The inevitable collapse of Jetty following berthing impact

23 Impact damage

24 Causeway damage Rock armour inadequate to resist the design wave Repair is accepted as a consequence FRA skilled at this repair Cyclone damage Causeway damage Exposed unprotected rear of jetty Permitted fill within sheet piled structure to be scoured out Partial collapse of slab Jetty Repair at another jetty

25 Examples of actions taken Temporary repairs and temporary steel overlay

26 New temporary steel overlay and piles

27 New temporary concrete overlay

28 New bollards installed to prevent vehicular traffic onto unsafe sections of jetty

29 Concrete durability Temperature affects Rate at which chlorides migrate into the concrete The quantity of chloride ions necessary to initiate corrosion NZ 0.40% Fiji 0.21%

30 Modelled 3 mixes 30% fly ash 65% ground granulated blast furnace slag A mix incorporating 8% amorphous silica Found The mix containing 8% amorphous silica is not sufficiently durable The slag mix is adequately durable provided a cover of 55mm is maintained The 30% FA provides the best durability The durability is very sensitive to cover These recommendations were incorporated into a FRA Design Guide developed by MWH

31 To address the safety issues we developed the FRA Design Guide 100 year design life Fiji specific seismic loads GNS studies Seismic hazard map for Fiji Exposure classifications different to Australian or NZ classifications Deemed to comply concrete mixes Testing requirements for alternative concrete mixes Classifications/stress grades of common Fijian timbers for use in AS1720 Design standards to be adopted AS4997 Wave actions based on various papers Fender design methodology Ramp geometry Waiting shed performance specs

32 Thank you Questions? New jetty construction