Proof loading of bridges is an option to study existing bridges when crucial information is lacking. When proof loading is chosen, the question arises which maximum load should be attained during the test to demonstrate sufficient capacity, and which criteria, the “stop criteria”, based on the measurements during the test, would indicate that the test needs to be aborted before reaching the maximum desired load. A review of the literature identifies the stop criteria in currently used codes and guidelines. Beams sawn from the Ruytenschildt bridge were tested in a controlled way in the laboratory and analyzed with regard to the stop criteria from the literature. Recommendations are given for the future development of stop criteria for flexure and shear. These recommendations will form the basis for a guideline on proof loading of existing concrete bridges that is under development in The Netherlands.

1. Challenge the future
Delft
University of
Technology
Development of Stop Criteria for
Proof Loading
Eva Lantsoght, Yuguang Yang, Rik Tersteeg, Cor van der Veen, Ane de Boer

2. 2Development of Stop Criteria for Proof Loading
Overview
• Introduction
• Why proof loading?
• Stop criteria?
• Overview of existing guidelines
• Lab testing for analysis
• Recommendations
• Summary and conclusions
Slab shear experiments, TU Delft

3. 3Development of Stop Criteria for Proof Loading
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. 4Development of Stop Criteria for Proof Loading
Why load testing? (2)

5. 5Development of Stop Criteria for Proof Loading
Stop criteria
• Safety philosophy
• Stop criteria:
• Further loading not permitted
• Failure near
• Irreversible damage near
MSc Thesis W. Vos

6. 6Development of Stop Criteria for Proof Loading
Proof load testing of bridges
• Apply predetermined load to
bridge
• Information lacking
• Damage due to ASR, …
• Proof load testing
• Immediate approval of bridge
• Recalculate updated β

7. 7Development of Stop Criteria for Proof Loading
Existing Guidelines for proof loading
• Europe: DAfStB Richtlinie
• Stop criteria
• Concrete strain
• Steel strain
• Crack width and residual
crack width
• Residual deflection
• For flexure
• Structures with large
existing cracking?

8. 8Development of Stop Criteria for Proof Loading
Existing Guidelines for proof loading
• North America:
• Buildings: ACI 437.2M-13
• Bridges: Manual of Bridge
Rating Through Load
Testing (1998)
• ACI 437.2M-13 stop criteria:
• Residual deflection
• Permanency ratio
• Deviation from Linearity
Index

9. 9Development of Stop Criteria for Proof Loading
Research need
• Guideline for proof loading of existing bridges for the
Netherlands
• Flexure + shear
• Stop criteria?

10. 10Development of Stop Criteria for Proof Loading
Lab testing for analysis (1)
• Beams from Ruytenschildt Bridge
• Cyclic loading protocol
• Tests: Failure in shear and flexure
• Measurements:
• Lasers: deflection of beam
• LVDTs: crack opening
• Acoustic emission sensors
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)

11. 11Development of Stop Criteria for Proof Loading
Lab testing for analysis (2)
RSB 01F 02A 02B 03F 03A
d (mm) 503 515.5 520 521 515
Ac (m2) 0.290 0.297 0.307 0.596 0.537
Rebar 4Ø22
4Ø19
4Ø22
4Ø19
4Ø22
5Ø19
9Ø22
8Ø19
7Ø22
8Ø19
ρl 0.91% 0.89% 0.96% 0.95% 0.92%

12. 12Development of Stop Criteria for Proof Loading
Lab Testing for analysis (2)
• Analysis of stop criteria ACI 437.2M-13 and DAfStB Richtlinie for
RSB03F – Flexure test
ACI 437.2M-13
Criterion
Load (kN) DAfStB
Criterion
Load (kN)
Δr 340 Δr 150
Ipr >Pu w new crack 300
IDL 250 Strain -
PACI,st 250 PDA,st 150
Pu 606.6 Pu 606.6
PACI,st/Pu 0.41 PDA,st/Pu 0.25
Tersteeg, R. H. D. (2015). "Proefbelastingen op betonnen bruggen," B.Sc. Thesis,
Delft University of Technology, Delft, The Netherlands, pp. 69.

13. 13Development of Stop Criteria for Proof Loading
Lab Testing for analysis (3)
• Analysis of stop criteria ACI 437.2M-13 and DAfStB Richtlinie for
RSB03A – Shear test
ACI 437.2M-13
Criterion
Load (kN) DAfStB
Criterion
Load (kN)
Δr >Pu Δr >Pu
Ipr >Pu w new crack 690
IDL 390 Strain -
PACI,st 390 PDA,st 690
Pu 706.7 Pu 706.7
PACI,st/Pu 0.55 PDA,st/Pu 0.98
Tersteeg, R. H. D. (2015). "Proefbelastingen op betonnen bruggen," B.Sc. Thesis,
Delft University of Technology, Delft, The Netherlands, pp. 69.

14. 14Development of Stop Criteria for Proof Loading
Recommendations
• Use cyclic load protocol
• Study linearity and repeatability of results
• Flexure: Stop criteria exceeded long before failure
• Suitable stop criteria
• Crack width criterion from DAfStB + add lower bound
• Residual deflection DAfStB / ACI 437.2M-13 + minimum load level
• Deviation from Linearity ACI 437.2M-13: consistent performance except for
retested beam
• BUT: Deviation from Linearity and Permanency Ratio depend on applied
loading protocol
• Shear:
• Need to develop stop criteria
• Research on acoustic emission measurements

15. 15Development of Stop Criteria for Proof Loading
Summary and conclusions
• Proof loading to approve existing
bridges
• Existing guidelines:
• Only flexure
• Cracked structures?
• Development of stop criteria for
Dutch Guideline
• Laboratory experiments
• Check existing stop criteria
• Stop criteria
• Available for flexure
• Adaptations for bridges needed
• Current research: shear
Viaduct Zijlweg, tested in summer 2015

16. 16Development of Stop Criteria for Proof Loading
Contact:
Eva Lantsoght
E.O.L.Lantsoght@tudelft.nl // elantsoght@usfq.edu.ec
+31(0)152787449