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Challenge the future
Delft
University of
Technology
Determination of loading protocol and stop
criteria for proof loading ...
2Determination of loading protocol and stop criteria for proof loading with beam tests
Overview
• Introduction
• Why proof...
3Determination of loading protocol and stop criteria for proof loading with beam tests
Why load testing? (1)
Bridges from ...
4Determination of loading protocol and stop criteria for proof loading with beam tests
Elements for load testing
• Target ...
5Determination of loading protocol and stop criteria for proof loading with beam tests
Existing Guidelines for proof loadi...
6Determination of loading protocol and stop criteria for proof loading with beam tests
Research need
•Stop criteria for fl...
7Determination of loading protocol and stop criteria for proof loading with beam tests
Experiments (1)
• Beams P804 and P5...
8Determination of loading protocol and stop criteria for proof loading with beam tests
Experiments (2)
Test a
(mm)
dl
(mm)...
9Determination of loading protocol and stop criteria for proof loading with beam tests
Experiments (3)
P804A1 P804A2
P804B...
10Determination of loading protocol and stop criteria for proof loading with beam tests
Recommendations (1)
• Cyclic loadi...
11Determination of loading protocol and stop criteria for proof loading with beam tests
Recommendations (2)
Existing flexu...
12Determination of loading protocol and stop criteria for proof loading with beam tests
Summary and conclusions
• Proof lo...
13Determination of loading protocol and stop criteria for proof loading with beam tests
Contact:
Eva Lantsoght
E.O.L.Lants...
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Determination of loading protocol and stop criteria for proof loading with beam tests

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Proof loading of existing bridges is an interesting option when insufficient information about a bridge is available. To safely carry out a proof loading test, high loads are placed on the bridge. To avoid permanent damage to the structure, a controlled loading protocol needs to be described, and the measurements need to be closely monitored to identify the onset of distress. The criteria from existing codes and guidelines to evaluate the measurements, called stop criteria, are not universally applicable. To develop recommendations for proof loading of reinforced concrete solid slab bridges, beam experiments were analysed. The beams were heavily instrumented to evaluate the existing stop criteria, and possibly develop new stop criteria. The result of these experiments is the development of a standard loading protocol for the proof loading of reinforced concrete slab bridges. Recommendations for the use of the stop criteria are also formulated. These insights are used to develop a new guideline for the proof loading of reinforced concrete slab bridges in the Netherlands.

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Determination of loading protocol and stop criteria for proof loading with beam tests

  1. 1. Challenge the future Delft University of Technology Determination of loading protocol and stop criteria for proof loading with beam tests Eva Lantsoght, Yuguang Yang, Cor van der Veen, Ane de Boer, Dick Hordijk
  2. 2. 2Determination of loading protocol and stop criteria for proof loading with beam tests Overview • Introduction • Why proof loading? • Stop criteria? • Overview of existing guidelines • Lab experiments • Results • Recommendations • Summary and conclusions Slab shear experiments, TU Delft
  3. 3. 3Determination of loading protocol and stop criteria for proof loading with beam tests Why load testing? (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. 4Determination of loading protocol and stop criteria for proof loading with beam tests Elements for load testing • Target load • Loading protocol • Stop criteria: • Further loading not permitted • Failure near • Irreversible damage near MSc Thesis W. Vos
  5. 5. 5Determination of loading protocol and stop criteria for proof loading with beam tests Existing Guidelines for proof loading • DAfStB Stop criteria for flexure • Concrete strain • Steel strain • Crack width and residual crack width • Residual deflection • ACI 437.2M-13 Acceptance criteria for flexure: • Residual deflection • Permanency ratio • Deviation from Linearity Index • No stop criteria for shear
  6. 6. 6Determination of loading protocol and stop criteria for proof loading with beam tests Research need •Stop criteria for flexure and shear •Loading protocol for field testing
  7. 7. 7Determination of loading protocol and stop criteria for proof loading with beam tests Experiments (1) • Beams P804 and P502 cast in lab: plain bars • Cyclic loading protocol • Number of cycles • Loading speed • Tests: Failure in shear and flexure • Measurements: • Lasers: deflection of beam • LVDTs: crack opening + horizontal deformation • Acoustic emission sensors in shear span Flexural failure, P804A1 Shear failure, P804A2
  8. 8. 8Determination of loading protocol and stop criteria for proof loading with beam tests Experiments (2) Test a (mm) dl (mm) fcm (MPa) Pshear (kN) Pmoment (kN) Ppred (kN) FMpred Pu (kN) FM P804A1 3000 755 63.5 273 199 199 F 207 F P804A2 2500 755 63.5 219 248 219 S 232 S P804B 2500 755 63.5 219 248 219 S 196 S P502A2 1000 465 71.5 150 154 150 S/F 150 F
  9. 9. 9Determination of loading protocol and stop criteria for proof loading with beam tests Experiments (3) P804A1 P804A2 P804B P502A2
  10. 10. 10Determination of loading protocol and stop criteria for proof loading with beam tests Recommendations (1) • Cyclic loading protocol • Constant loading speed • Four load levels • After SLS: use small steps to go to interim and target level
  11. 11. 11Determination of loading protocol and stop criteria for proof loading with beam tests Recommendations (2) Existing flexural cracks? Failure mechanism Uncracked Cracked Flexural failure εc < 0.8 ‰ – εc0 wmax ≤ 0.5 mm wres ≤ 0.1 mm wres < 0.3wmax Stiffness reduction ≤ 25 % Deformation profiles Load-displacement graph εc < 0.8 ‰ – εc0 wmax ≤ 0.3 mm wres ≤ 0.1 mm wres < 0.2wmax Stiffness reduction ≤ 5 % Deformation profiles Load-displacement graph Shear failure εc < 0.8 ‰ – εc0 wmax ≤ 0.3 mm Stiffness reduction ≤ 5 % Deformation profiles Load-displacement graph εc < 0.8 ‰ – εc0 Stiffness reduction ≤ 5 % Deformation profiles Load-displacement graph
  12. 12. 12Determination of loading protocol and stop criteria for proof loading with beam tests Summary and conclusions • Proof loading to approve existing bridges • Existing guidelines: • Only flexure • Precracked structures? • Laboratory testing • Loading protocol • Cyclic, constant loading speed • Proposal with 4 levels • Stop criteria • Based on ACI and DAfStB • Effect of cracking • Difference between flexure and shear Viaduct Zijlweg, tested in summer 2015
  13. 13. 13Determination of loading protocol and stop criteria for proof loading with beam tests Contact: Eva Lantsoght E.O.L.Lantsoght@tudelft.nl // elantsoght@usfq.edu.ec +31(0)152787449

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