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Proof loading of existing bridges

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Proof loading of existing bridges

  1. 1. Challenge the future Delft University of Technology Proof loading of existing bridges Recent developments in The Netherlands Dr. ir. Eva Lantsoght, Prof. dr. ir. Dick Hordijk, Dr. ir. Cor van der Veen, Dr. ir. Ane de Boer
  2. 2. 2Proof loading of existing bridges Overview • Introduction • Applied methods • Results • Summary and conclusions Slab shear experiments, TU Delft
  3. 3. 3Proof loading of existing bridges Background (1) Bridges from 60s and 70s The Hague in 1959 Increased live loads common heavy and long truck (600 kN) End of service life + larger loads
  4. 4. 4Proof loading of existing bridges Background (2)
  5. 5. 5Proof loading of existing bridges Background (3) • Replacing all bridges = too expensive => Prioritize efforts! Highways in the Netherlands
  6. 6. 6Proof loading of existing bridges Principle of Levels of Approximation Model Code 2010 (1) • Approach from fib Model Code 2010 • Solution strategy = different levels of approximation • Eg: Shear capacity in Model Code 2010
  7. 7. 7Proof loading of existing bridges Principle of Levels of Approximation Model Code 2010 (2) • For assessment: • LoA 1: Quick Scan • LoA 2: LFEA • LoA 3: NLFEA + probabilistic analysis • LoA 4: Proof loading
  8. 8. 8Proof loading of existing bridges Proof loading of bridges • Apply predetermined load to bridge • Information lacking • Damage due to ASR, … • But: probabilistic analysis • Maximum load? • “Stop criteria”?
  9. 9. 9Proof loading of existing bridges Current codes for proof loading • Europe: DAfStB Richtlinie • North America: • Buildings: ACI 437.2M-13 • Bridges: Manual of Bridge Rating Through Load Testing (1998) • But: stop criteria for cracked structures?
  10. 10. 10Proof loading of existing bridges Research need • Guideline for proof loading of existing bridges for The Netherlands • Flexure + shear • Stop criteria?
  11. 11. 11Proof loading of existing bridges Methods • Proof load tests: • Vlijmen-Oost • Halvemaans Bridge, Alkmaar • Ruytenschildt Bridge • Viaduct in the Zijlweg
  12. 12. 12Proof loading of existing bridges Vlijmen-Oost • Loading: BELFA • Viaduct with ASR • Testing while viaduct was in service • Measurements: • Lasers • Acoustic emissions • LVDTs
  13. 13. 13Proof loading of existing bridges Halvemaans Bridge Alkmaar • Load application: Mammoet • Flexural capacity • Bridge closed for 1 night • Measurements: • Lasers • Acoustic emissions • LVDTs
  14. 14. 14Proof loading of existing bridges Ruytenschildt Bridge (1) • Load application: Mammoet • Measurements: • Lasers • Acoustic emissions (2 teams) • LVDTs • Sawcut for testing • Testing to failure
  15. 15. 15Proof loading of existing bridges Ruytenschildt Bridge (2) • Study cracks and deformations for applied loads • Crack formation: acoustic emissions measurements • Control load process
  16. 16. 16Proof loading of existing bridges Proofloading Ruytenschildt Bridge Existing bridge Partial demolition and building new bridge
  17. 17. 17Proof loading of existing bridges Ruytenschildt Bridge (4)
  18. 18. 18Proof loading of existing bridges Viaduct in the Zijlweg • Loading: Mammoet • Viaduct with ASR • Viaduct closed for 1 week • Measurements: • Lasers • Acoustic emissions • LVDTs
  19. 19. 19Proof loading of existing bridges Results of proof load tests (1) • Load application method: • Hydaulic jacks: allows higher load on wheel prints • BELFA: limited to 90 ton
  20. 20. 20Proof loading of existing bridges Results of proof load tests (2) • Determination of maximum load in test: • Moment due to applied load • = moment due to Eurocode loads • Find critical location • Same procedure for shear • Use LFEA
  21. 21. 21Proof loading of existing bridges Results of proof load tests (3) • Different reliability levels • As prescribed by NEN 8700:2011 • Different requirements for structure • Different partial load factors Case Ptot (kN) Ptot (metric ton) EC 1259 128 RBK Design 1257 128 RBK Reconstuction + 5% 1146 117 RBK Reconstruction 1091 111 RBK Usage 1050 107 RBK Disapproval 1049 107 SLS 815 83
  22. 22. 22Proof loading of existing bridges Results of proof load tests (4) 0 20 40 60 80 100 120 0 50 100 150 Appliedtotalload [tonnes] Time [min] Loading procedure SLS Reconstruction Reconstruction + 5%
  23. 23. 23Proof loading of existing bridges Results of proof load tests (5) • Measurements: experience • Development of aluminum frame • Research on Acoustic Emissions • Necessary for stop criteria • Load cells at jacks LVDT Laser distance finder
  24. 24. 24Proof loading of existing bridges Summary and conclusions • Proof loading: LoA 4 • Research in The Netherlands • Executed load tests • Loading with hydraulic jacks • Measurement and interpretation • Current work: • Determination of maximum load • Stop criteria
  25. 25. 25Proof loading of existing bridges Contact: Eva Lantsoght E.O.L.Lantsoght@tudelft.nl // elantsoght@usfq.edu.ec +31(0)152787449

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