Development Island Vehicle Access

Transcription

1 Elizabeth Quay Water Front Development Island Vehicle Access Bridge Small Bridges Conference - 23 rd November 2015

2 Presentation Outline Project Overview Key Challenges Description of Island Vehicle Access Bridge Design Vehicle Design Issues and Construction Staging Diaphragm Walls Architectural Fascia Panels Deck Units Deck Slab Steel Edge Beams Earthworks Miscellaneous Acknowledgments 2

3 Project Overview Elizabeth Quay is development being delivered by the Metropolitan Redevelopment Authority (MRA) on behalf of the State Government of Western Australia. Aim is to revitalise the city of Perth and return the city s focus to the Swan River. Development covers nearly 10 hectares of riverfront land with a 2.7 hectare inlet surrounded by a split level promenade. 3

4 Project Overview Managing Contractor: Leighton Broad Lead Architect: ARM Architecture Lead Structural Engineer: Arup Sub-Contractor: Civmec Sub-Contractor: GFWA 4

5 Project Overview 5

6 Project Overview 6

7 Project Overview 7

8 Project Overview 8

9 Key Challenges Novated to Managing Contractor Architectural shape of bridge Garden bed on bridge Determination of the vehicle loading Services Construction in either the wet or dry B2 exposure classification for underside of deck Changing the substructure of the bridge (Perimeter edge inlet wall) 9

10 Island Vehicle Access Bridge The curved profile of the bridge deck required careful consideration be given to the form of the bridge. In-situ concrete post tensioning and steel beams composite with a deck slab were considered. Prestressed deck units with an in-situ deck slab was adopted. Unknown if bridge would be constructed in the wet or the dry. Thus precast deck units were considered the most appropriate construction form as they offered a safer and more efficient construction option over water. Deck slab cantilever varied on each side of the bridge to a maximum of 2.58m. 10

11 Island Vehicle Access Bridge Allow kayak access under the bridge 1.2m clearance above HAT. Arup initially engaged by ARM Architecture to undertake the design of the vehicle bridge. The original design of the inlet perimeter wall, by others, was a sheet pile and anchor solution. The design of the substructure of the vehicle bridge was a continuation of this wall type. A corrosion allowance was used in the design along with cathodic protection. Architectural fascia reinforced concrete panels with in fill concrete between the sheet piles and fascia panels was proposed. 11

12 Island Vehicle Access Bridge Upon Leighton Broad being award the Managing Contractor s role, Arup were novated to Leighton Broad to complete the design of the vehicle bridge. As part of a value engineering exercise steel sheet piles and anchors were deemed too expensive and brought with it associated problems in relation to anchoring into the zone of potential future building piles and a complex anchor layout. Future maintenance of the anchors was also seem as problematic as too the cathodic protection system required for the sheet piles. Other options were explored, including contiguous flight auger (CFA) secant piled walls and diaphragm walls. 12

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17 Island Vehicle Access Bridge 17

18 Island Vehicle Access Bridge 18

19 Design Vehicle Rubbish truck, ambulance, fire trucks and utility vehicles were required to access the island M18 vehicle AS tonne vehicle - two axles 19

20 Design Vehicle 20

21 Diaphragm Walls GFWA were awarded the sub-contract for the design and construction for the inlet perimeter wall. Diaphragm walls are commonly used for sea walls. Have the benefit of a high control of verticality due to the bucket and guide wall system. Walls were typically 600mm thick with a maximum panel length of approx. 6m. Shear keys with a water stop between adjacent wall panels. Glass fibre reinforced plastic (GFRP) reinforcement was used on the inlet face of the walls without architectural fascia panels for durability purposes (fascia panels at vehicle access bridge). 21

22 Diaphragm Walls Lateral deflection a significant design consideration. Two conditions were outlined in the performance specification for the inlet wall. First condition permitted a deflection of δ/h of 0.75%. Wall deflecting upon completing the backfill behind the wall and excavation in front of the wall. Second condition permitted a deflection of δ/h of 0.25%. Wall deflection which occurs in response to applying the settlement sensitive pavement structure and the design surcharge loading behind the wall. 22

23 Diaphragm Walls 23

24 Architectural Fascia Panels Architectural fascia panels were located facing the majority of the diaphragm walls. Typically 150mm thick with patterned protrusions. Moulds were fabricated of the patterned protrusions. Panels were constructed at Civmec s fabrication yard in Henderson, WA. High quality finish achieved. Visual inspections undertaken and repair work undertaken to the protrusions where required. 24

25 Architectural Fascia Panels Two methods used to install the fascia panels. Strong back beams. Cantilever rigging frame used where access to the front of the inlet wall was constrained. Ferrules cast into the back face of the wall. L-shape starter bars to be threaded in to provide a connection between the fascia panel and the in-situ concrete cast in the void between the back of the fascia panel and the front of the diaphragm wall. Extended to 0.5m below LAT and generally installed in the dry. 25

26 Architectural Fascia Panels 26

27 Architectural Fascia Panels 27

28 Architectural Fascia Panels 28

29 Architectural Fascia Panels 29

30 Architectural Fascia Panels 30

31 Architectural Fascia Panels 31

32 Architectural Fascia Panels 32

33 Deck Units Prestressed precast concrete constructed at Delta Corporation s fabrication yard in Herne Hill, WA. Cross section of the bridge consisted of 9 x 500mm deep deck units. 7 x 596mm deck units. 2 x 1192mm deck units at each end with the large deck slab cantilevers. Connected to the headstock cast on the diaphragm wall via a dowel, which was then grouted up. Serviceability was the governing limit state B2 exposure classification AS

34 Deck Units This required the underside of the deck units to be in compression under a serviceability limit state load combination that comprised permanent effects plus 50% of the serviceability live load. During the detailed design the stressing bed which had previously been advised as being available and now unavailable. Thus a stressing bed with a reduced capacity was required to be used which didn t have sufficient prestress to satisfy the B2 exposure classification of AS It was advised that the bridge deck would be constructed in the dry thus there was an opportunity to prop the deck units during the construction of the deck slab. 34

35 Deck Units Once the deck slab has reached sufficient strength and the deck units had become composite with the deck slab the props could be removed. This solution meant that the deck units did not have to support the self weight of the wet deck slab concrete and thus meant the amount of prestress could be reduced to within the stressing capacity of the available stressing bed. 35

36 Deck Units 36

37 Deck Units 37

38 Deck Units 38

39 Deck Units 39

40 Deck Units 40

41 Deck Slab - Services 1 x 200 OD conduit for fire 1 x 150 OD for irrigation 1 x 125 OD for gas 1 x 110 OD for sewer 1 x 110 OD for water 1 x 50 OD for irrigation 3 x 110 OD for power 1 x 110 OD spare for power 1 x 110 OD for NBN 1 x 110 OD spare for comms 1 x 110 OD spare for A/V 1 x 50 OD for CCTV 1 x 50 OD for comms 41

42 Deck Slab - Services Divided into two service corridors 1100mm wide each. Deck slab was thickened at the service corridors and the deck units removed at these locations. The thickened deck slab spanned between adjacent deck units. Punching shear was checked as the service corridors ran along the path of the M18 design vehicle. 42

43 Deck Slab 43

44 Deck Slab 44

45 Deck Slab 45

46 Steel edge beams fabricated at Alltype Engineering at Naval Base, WA. Installation on site used a small crane to hold the steel edge beams in place over the chemically anchored permanent hold down bolts. Small crane was also used to confirm the positioning of the steel edge beams. Temporary hold down bolts were used to ensure the locality of the steel edge beam before the permanent chemically anchored hold down bolts were constructed. 46

47 Steel Edge Beam The detail on the inside face incorporated a steel mesh which acts to prevent debris from falling into the inlet below whilst allowing water to drain into the inlet. No hand railing was proposed for the bridge which was consistent with the remainder of the promenade, however the connection was designed such that one could be installed on top in the future if required. 47

48 Steel Edge Beam 48

49 Steel Edge Beam 49

50 Steel Edge Beam 50

51 Steel Edge Beam 51

52 Steel Edge Beam 52

53 Steel Edge Beam 53

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55 Steel Edge Beam 55

56 Earthworks Significant earthworks required for Elizabeth Quay. A sea bund was constructed to facilitate the construction of the man made island. The inlet was flooded before the island construction had been completed to enable construction of the maritime infrastructure such as the floating walkway and mooring and berthing facilities. 56

57 Earthworks 57

58 Earthworks 58

59 Miscellaneous Garden bed located on the bridge by ARM Architects. A drainage cell was detailed along with the cross fall and longitudinal fall of the bridge served to transport water from the garden bed off the bridge and protect the deck waterproofing. Waterproofing under the garden bed Bituthene Concrete upstands. Removable bollards. Bike racks. Paving. 59

60 Miscellaneous 60

61 Miscellaneous 61

62 Acknowledgements Acknowledgements: - Arup - Leighton Broad - ARM Architecture - GFWA - Civmec - Delta Corporation - Alltype Engineering - MRA - WGE 62

63 Island Vehicle Access Bridge Questions? 63