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Design Of the Alfords Pt Bridge Duplication

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Design Of the Alfords Pt Bridge

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DESIGN OF THE ALFORDS POINT BRIDGE Prepared 17/08/08 Duplication 1 M1
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 2
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE The existing bridge is a twin concrete box girder, built by erecting precast segments erected on falsework trusses and 100 mm wide wet joints poured between segments. It was prestressed longitudinally and transversely. 3
DESIGN OF ALFORDS POINT BRIDGE Existing Bridge • Opened to traffic in 1973 • Designed for HS20-44 truck and lane loading in accordance with NAASRA Highway Bridge Design Specification 1970. • Designed by Guyon, Schere, Harris & Sutherland in London • Constructed by John Hollands • Provision made for future duplication by construction of piles, pilecaps and spread footings and Abutments for future bridge • A condition assessment and structural assessment of the bridge was carried out. 4
DESIGN OF ALFORDS POINT BRIDGE Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Section capacity envelope 5
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Under-estimation of long term creep and shrinkage mean the fingers of the deck joint no longer overlap, even in summer 6
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE The starter bars of the existing pile caps were protected by a low strength hollow concrete stub. 7
DESIGN OF ALFORDS POINT BRIDGE Concept Design • Alternative superstructure types and construction methods evaluated • Wider carriageway layout • Single cell box girder vs twin box girder • Incrementally launched twin concrete box girder was the preferred solution 8
DESIGN OF ALFORDS POINT BRIDGE Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE General Arrangement Spans 33.93, 9@41.910 and 34.020 m 9
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Existing bridge Traffic carriageway 11.580 m Footway 1.200 m Box depth 2286 mm New Bridge Traffic carriageway 10.750 m Shared path 3.365 m Box depth 2600 mm 10
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Box girder cross section 11
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Piers 12
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Pier columns 13
DESIGN OF ALFORDS POINT BRIDGE Detail Design Parameters • Bridge designed to AS 5100 for SM 1600 traffic loading. • Crack control during launching – No de-compression of the box girder due to self weight effects during launching – Max tensile stress of 0.5√ f’c during launching when considering additional effects of differential temperature and bearing level tolerances • Shear and torsion design in accordance with the AASHTO LRFD Bridge Design Specification but with AS 5100 capacity reduction factors • Combination of transverse bending of the cross section and shear • 12.5ºC reduction in temperature of the box girder assumed during any one launching cycle 14
DESIGN OF ALFORDS POINT BRIDGE Foundation Evaluation • Detailed evaluation of the existing bridge foundations to support the heavier superstructure and higher traffic loadings was undertaken. • New Pier columns hollow to match the existing and reduce weight • New bore holes drilled and the bore logs correlated to the original bore log descriptions. 15
DESIGN OF ALFORDS POINT BRIDGE Detail Details • The drawings included schematic details for the casting yard and launching system – spline beam support assumed under casting yard. • It included a end frame to allow final launching of end segment • Launching over elastomeric bearings – bearings detailed in launching and in-service configuration. • Design parameters for launching nose 16
DESIGN OF ALFORDS POINT BRIDGE Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 17
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 18
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 19
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 20
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Concentric Prestress 21
DESIGN OF ALFORDS POINT BRIDGE Launching • Bridge straight but located on sag curve between grades of -4.17% and 6.7% • Longitudinal grade at launching Abutment 6.5% and at Abutment A -2.3%. • Superstructure launched from the southern (Menai end) due to larger working area and it allowed construction traffic to merge back into the traffic flow at the top of the hill. • Launching system consists of 2 pairs of heavy lift jacks travelling along two fixed tendons between the Abutment and the casting yard. • A pair of launching noses assumed for design 22
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Vertical curve 23
DESIGN OF ALFORDS POINT BRIDGE Launching • Coefficients of 0% and 4% used to determine maximum launching and braking force. • During downhill launching the force on the pier = slope component of vertical force – friction. • However, during casting of each new segment it is imperative that the end of the constructed superstructure be fixed close to the end of the casting bed. • Launching over elastomerics has the advantage the force required to fix the end of the superstructure during thermal contraction is reduced. 24
DESIGN OF ALFORDS POINT BRIDGE 2200 2200 Fully launched PUSHING -5350 -3135 -2215 Fully launched -5600 -2300 -3300 Launching Nose at Pier 2 Total Force (kN) Force due to 12.5ºC thermal contraction (kN) Force due to bearing slope (kN) BRAKING Launching Forces 25
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Casting Yard - Layout 26
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Segment launching 27
DESIGN OF ALFORDS POINT BRIDGE Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Launching jacks 1 28
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Launching system 29
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Heavy lifting jacks bearing on braking pin 30
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Braking pin 31
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Auxiliary braking device 32
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Launching over elastomeric bearings 33
DESIGN OF ALFORDS POINT BRIDGE Contractor’s design modifications – Permanent works • Single launching nose on inside web of each box • Re-design of Pier 1 with new piles, pile cap and solid column • Insitu parapets replaced with parapet shells filled with insitu concrete 34
DESIGN OF ALFORDS POINT BRIDGE Contractor’s design modifications – Temporary Works • Polyurethane wheels for side guides • Discrete supports in the casting yard • Single launching nose 35
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Stiffened end of box girder to use single launching nose 36
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Casting yard 37
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Side Guides 38
DESIGN OF ALFORDS POINT BRIDGE Design Team • Concept and Detail Design undertaken by Bridge Engineering • Proof Check carried out by Taylor & Herbert • Contractors design modifications undertaken by Maunsells 39
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification 40
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Modified abutments stabilized with a couple of rock anchors 41
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Pier 10 column reinforcement 42
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Blister for continuity prestressing 43
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Box girder reinforcement 44
The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Staggered prestressing tendons 45
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Diaphragm reinforcement 46
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Stressing continuity tendons 47
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Long nose jack 48
DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Final bearing configuration 49
The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE PTFE/Stainless steel sliding interface installed on top of elastomeric bearings at ends of bridge where shear deflection capacity of bearings is inadequate. 50

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Design Of the Alfords Pt Bridge Duplication

  • 1. DESIGN OF THE ALFORDS POINT BRIDGE Prepared 17/08/08 Duplication 1 M1
  • 2. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 2
  • 3. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE The existing bridge is a twin concrete box girder, built by erecting precast segments erected on falsework trusses and 100 mm wide wet joints poured between segments. It was prestressed longitudinally and transversely. 3
  • 4. DESIGN OF ALFORDS POINT BRIDGE Existing Bridge • Opened to traffic in 1973 • Designed for HS20-44 truck and lane loading in accordance with NAASRA Highway Bridge Design Specification 1970. • Designed by Guyon, Schere, Harris & Sutherland in London • Constructed by John Hollands • Provision made for future duplication by construction of piles, pilecaps and spread footings and Abutments for future bridge • A condition assessment and structural assessment of the bridge was carried out. 4
  • 5. DESIGN OF ALFORDS POINT BRIDGE Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Section capacity envelope 5
  • 6. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Under-estimation of long term creep and shrinkage mean the fingers of the deck joint no longer overlap, even in summer 6
  • 7. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE The starter bars of the existing pile caps were protected by a low strength hollow concrete stub. 7
  • 8. DESIGN OF ALFORDS POINT BRIDGE Concept Design • Alternative superstructure types and construction methods evaluated • Wider carriageway layout • Single cell box girder vs twin box girder • Incrementally launched twin concrete box girder was the preferred solution 8
  • 9. DESIGN OF ALFORDS POINT BRIDGE Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE General Arrangement Spans 33.93, 9@41.910 and 34.020 m 9
  • 10. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Existing bridge Traffic carriageway 11.580 m Footway 1.200 m Box depth 2286 mm New Bridge Traffic carriageway 10.750 m Shared path 3.365 m Box depth 2600 mm 10
  • 11. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Box girder cross section 11
  • 12. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Piers 12
  • 13. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Pier columns 13
  • 14. DESIGN OF ALFORDS POINT BRIDGE Detail Design Parameters • Bridge designed to AS 5100 for SM 1600 traffic loading. • Crack control during launching – No de-compression of the box girder due to self weight effects during launching – Max tensile stress of 0.5√ f’c during launching when considering additional effects of differential temperature and bearing level tolerances • Shear and torsion design in accordance with the AASHTO LRFD Bridge Design Specification but with AS 5100 capacity reduction factors • Combination of transverse bending of the cross section and shear • 12.5ºC reduction in temperature of the box girder assumed during any one launching cycle 14
  • 15. DESIGN OF ALFORDS POINT BRIDGE Foundation Evaluation • Detailed evaluation of the existing bridge foundations to support the heavier superstructure and higher traffic loadings was undertaken. • New Pier columns hollow to match the existing and reduce weight • New bore holes drilled and the bore logs correlated to the original bore log descriptions. 15
  • 16. DESIGN OF ALFORDS POINT BRIDGE Detail Details • The drawings included schematic details for the casting yard and launching system – spline beam support assumed under casting yard. • It included a end frame to allow final launching of end segment • Launching over elastomeric bearings – bearings detailed in launching and in-service configuration. • Design parameters for launching nose 16
  • 17. DESIGN OF ALFORDS POINT BRIDGE Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 17
  • 18. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 18
  • 19. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 19
  • 20. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE 20
  • 21. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Concentric Prestress 21
  • 22. DESIGN OF ALFORDS POINT BRIDGE Launching • Bridge straight but located on sag curve between grades of -4.17% and 6.7% • Longitudinal grade at launching Abutment 6.5% and at Abutment A -2.3%. • Superstructure launched from the southern (Menai end) due to larger working area and it allowed construction traffic to merge back into the traffic flow at the top of the hill. • Launching system consists of 2 pairs of heavy lift jacks travelling along two fixed tendons between the Abutment and the casting yard. • A pair of launching noses assumed for design 22
  • 23. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Vertical curve 23
  • 24. DESIGN OF ALFORDS POINT BRIDGE Launching • Coefficients of 0% and 4% used to determine maximum launching and braking force. • During downhill launching the force on the pier = slope component of vertical force – friction. • However, during casting of each new segment it is imperative that the end of the constructed superstructure be fixed close to the end of the casting bed. • Launching over elastomerics has the advantage the force required to fix the end of the superstructure during thermal contraction is reduced. 24
  • 25. DESIGN OF ALFORDS POINT BRIDGE 2200 2200 Fully launched PUSHING -5350 -3135 -2215 Fully launched -5600 -2300 -3300 Launching Nose at Pier 2 Total Force (kN) Force due to 12.5ºC thermal contraction (kN) Force due to bearing slope (kN) BRAKING Launching Forces 25
  • 26. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Casting Yard - Layout 26
  • 27. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Segment launching 27
  • 28. DESIGN OF ALFORDS POINT BRIDGE Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Launching jacks 1 28
  • 29. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Launching system 29
  • 30. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Heavy lifting jacks bearing on braking pin 30
  • 31. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Braking pin 31
  • 32. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Auxiliary braking device 32
  • 33. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Launching over elastomeric bearings 33
  • 34. DESIGN OF ALFORDS POINT BRIDGE Contractor’s design modifications – Permanent works • Single launching nose on inside web of each box • Re-design of Pier 1 with new piles, pile cap and solid column • Insitu parapets replaced with parapet shells filled with insitu concrete 34
  • 35. DESIGN OF ALFORDS POINT BRIDGE Contractor’s design modifications – Temporary Works • Polyurethane wheels for side guides • Discrete supports in the casting yard • Single launching nose 35
  • 36. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Stiffened end of box girder to use single launching nose 36
  • 37. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Casting yard 37
  • 38. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Side Guides 38
  • 39. DESIGN OF ALFORDS POINT BRIDGE Design Team • Concept and Detail Design undertaken by Bridge Engineering • Proof Check carried out by Taylor & Herbert • Contractors design modifications undertaken by Maunsells 39
  • 40. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification 40
  • 41. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Modified abutments stabilized with a couple of rock anchors 41
  • 42. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Pier 10 column reinforcement 42
  • 43. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Blister for continuity prestressing 43
  • 44. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Box girder reinforcement 44
  • 45. The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Staggered prestressing tendons 45
  • 46. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Diaphragm reinforcement 46
  • 47. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Stressing continuity tendons 47
  • 48. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Long nose jack 48
  • 49. DESIGN OF ALFORDS POINT BRIDGE The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE Final bearing configuration 49
  • 50. The existing box type Abutments needed significant modification Prepared 17/08/2008 DESIGN OF ALFORDS POINT BRIDGE PTFE/Stainless steel sliding interface installed on top of elastomeric bearings at ends of bridge where shear deflection capacity of bearings is inadequate. 50