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Assessment of slab bridges through proof loading in the Netherlands

Presentation of ACI Fall Convention 2017

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Assessment of slab bridges through proof loading in the Netherlands

  1. 1. Assessment of slab bridges through proofAssessment of slab bridges through proof loading in the Netherlandsloading in the Netherlands Eva Lantsoght, Cor van der Veen, Ane de Boer, Dick Hordijk
  2. 2. OverviewOverviewOverviewOverview • Introduction • Pilot proof load tests • Laboratory experiments • Recommendations • Preparation of proof load tests • Execution of proof load tests • Analysis of proof load tests • Summary and conclusions Slab shear experiments, TU Delft
  3. 3. Why load testing?Why load testing? 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. Safety philosphy of proof load testingSafety philosphy of proof load testing • Safety philosophy • Stop criteria: •Further loading not permitted •Failure near •Irreversible damage near MSc Thesis W. Vos
  5. 5. Research needResearch needResearch needResearch need Guideline for proof loading of existing (RC slab) bridges for the Netherlands Flexure + shear
  6. 6. TU Delft Proof Load TestsTU Delft Proof Load Tests • Proof load tests: •Heidijk 2007 •Medemblik 2009 •Vlijmen-Oost 2013 •Halvemaans Bridge 2014 •Ruytenschildt Bridge 2014 •Viaduct Zijlweg 2015 •Viaduct De Beek 2015 TU Delft proof load tests
  7. 7. Laboratory testingLaboratory testingLaboratory testingLaboratory testing • Ruytenschildt beams • Cyclic loading protocol • Analysis of stop criteria • Beams with plain bars • Effect of number of cycles • Effect of loading speed • Load levels • Analysis of stop criteria Beams RSB01 after failure (Yang, 2015) Yang, Y. (2015). "Experimental Studies on the Structural Behaviours of Beams from Ruytenschildt Bridge," Stevin Report 25.5-15-09, Delft University of Technology, Delft, 76 pp. Beams RSB02B after failure (Yang, 2015)
  8. 8. Preparation steps (1)Preparation steps (1) • Preliminary inspection and rating • Dimensions and material properties • Live load: lane load + design tandem • RBK load levels •Different β •Different load factors •γsw = 1.1 for proof load testing
  9. 9. Preparation steps (2)Preparation steps (2) • Critical position •Bending moment: largest moment •Shear: 2.5d from support • Required proof load •Same shear or bending moment as with load combination •Value → considered safety level
  10. 10. Preparation steps (3)Preparation steps (3) • Sensor plan: •Deflection profiles in longitudinal and transverse direction •Deflection at supports •Strain on bottom of cross-section •Reference strain measurements to correct for T •Opening existing cracks •Opening new cracks •Applied load => load cells •Acoustic emission measurements (current research)
  11. 11. Execution steps (1)Execution steps (1) • Cyclic loading scheme •Check linearity and reproducibility of measurements •Baseline load level • Load levels ≈ safety levels CC3 RBK: • Low level to check instrumentation • SLS • Intermediate level • Target proof load
  12. 12. Execution steps (2)Execution steps (2)
  13. 13. Execution steps (3)Execution steps (3)Execution steps (3)Execution steps (3)
  14. 14. Analysis StepsAnalysis Steps • Data analysis •Correct for T •Correct for support displacements •Make final plots for report
  15. 15. Summary and conclusionsSummary and conclusions • Proof loading to approve existing bridges, also for shear • Pilot proof load tests in the Netherlands + laboratory tests • Current recommendations • Further laboratory testing on slabs in shear is necessary Ruytenschildt Bridge
  16. 16. Contact: Eva Lantsoght // +31(0)152787449