As the bridge stock in The Netherlands and Europe is ageing, various methods to analyze existing bridges are being studied. Load testing of bridges is an option to study the capacity when crucial information about the structure is lacking. This information could be related to the material (for example, the effect of ASR on the capacity) as well as to the structural system (for example, the effect of restraints at the supports or transverse redistribution capacity). When it is decided to load test a bridge, the question arises which maximum load should be attained during the experiment to approve the capacity of the bridge, and which criteria, based on the measurements during the test, would indicate that the test needs to be aborted before reaching the maximum desired load (the “stop criteria”). A number of reinforced concrete slab bridges have been load tested over the course of the past few years. These load tests were pilot cases, in which the bridges were heavily equipped with sensors, to study the bridges’ behavior at critical positions for bending moment and shear. The test results were then extensively analyzed, and compared to the stop criteria available in the currently used codes and guidelines. As a result of the analysis and experiments, recommendations are given for proof loading of bridges. These recommendations are important, since they will form the basis of a guideline for proof loading of existing concrete bridges that is under development in The Netherlands.

1.  
Dr. ir. Eva Lantsoght
10/28/2016
1

2.  General overview of
work/research since
graduating from VUB
 Current research line:
(proof) load testing
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3.  2003-2008: burgerlijk
ingenieur bouwkunde
 2008-2009: M.S. in structural
engineering, Georgia Institute
of Technology
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4.  2009-2013: PhD in Civil
Engineering
 Concrete Structures research
group
 Promotor: Joost Walraven
 Co-Promotor: Cor van der Veen
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5.  Experiments
o Shear in reinforced concrete slabs
o 156 experiments
 Analytical work
o Extended Strip Model – plastic
analysis method for shear in slabs
o Probability-based improvement for EC
shear formula based on experiments
 Practical application
o Quick Scan for Rijkswaterstaat
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6.  2013 – …
 B.Sc. level, 5-year program
 Teaching (3 courses/semester):
o Reinforced Concrete I
o Reinforced Concrete II
o Construction Materials Lab
o Design of Pavements
o Structural Analysis I
 Research with students for
“Trabajo de Titulacion”
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7.  2013-2016: Profesor auxiliar
 2016 (?) - … : Profesor
Investigador Principal Titular
after concurso de
merecimientos y oposiciones
=> reduction of teaching,
more research
 ACI student chapter
 ASCE student chapter
 2013 – 2016: Starting ICV-Lab
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8.  Research:
o Publications of PhD research
o Analysis existing bridge Tambura
o Torsion in slabs
o Digital Image Correlation with
cheap tools
o Chancellor Grant 2015: Extended
Strip Model
o Chancellor Grant 2016: Stop
criteria load testing (research line
TU Delft)
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9.  Research lines:
o Difficulties:
• contact with Ministry of Public Works?
• Infomation (structural plans?)
• Mentality: no interest in existing structures
• Limited facilities
• No research group
o Approach:
• Desk research
• Presentations about existing structures and
maintenance
• Cooperation through international committees
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10.  2013 – now: 0,2 fte
 Short projects
 Summer 2013:
o Quick Scan spreadsheets for
Rijkswaterstaat
 Summer 2014:
o Fatigue of high-strenght concrete:
proposal for Dutch code
o Ruytenschildt Bridge collapse test
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11.  Summer 2015:
o Effect of ASR on shear- and
bending moment capacity
o Proof load test viaduct Zijlweg
o Support for research line proof
load testing
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12.  Summer 2016
o Research line proof load testing
o Beam tests + analysis of results
o Analysis results of proof load test
viaduct De Beek
o Literature review
o Overview previous proof load tests
in NL
o First draft guideline
o Vechtbrug: last week – collapse
test
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13.  ACI-ASCE 421: Design of reinforced concrete slabs
 ACI-ASCE 445: Shear & Torsion
 ACI-DAfStB 445-D: Shear Databases
 ACI 342: Evaluation of Concrete Bridges and Bridge
Elements
 TRB AFF30: Concrete Bridges
 TRB AFF40: Testing and Evaluation of Transportation
Structures
 IABMAS, IALCCE, IABSE, fib
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14.  Advanced structural
engineering
 2 junior engineers
 Bridges: La Armenia, Los
Pajaros (ILM), Villorita
 Buildings
 Project on concrete masonry
houses (EQ-resistant) for
coast of Ecuador
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15.  Introduction
o Why proof loading?
o Stop criteria?
 Overview of existing guidelines
 Past proof load tests by TU Delft
 Recommendations
o Preparation of proof load tests
o Execution of proof load tests
 Summary and conclusions
Slab shear experiments, TU Delft
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16. 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
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17. 10/28/2016 17

18. Diagnostic load testing Proof load testing
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Barcza ridge, Poland (Olaszek et
al., 2012)
Delaware (Jones, 2011)

19. Diagnostic load testing
 Calibration of FEM
 Strain gages over girder
height
 Low load levels
 Rating with updated FEM
Proof load testing
 Directly demonstrate that
bridge fulfils criteria
 Higher load levels
 Larger involved risk
 Follow measurements
 Stop criteria
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20.  Safety philosophy
 Stop criteria:
o Further loading not permitted
o Failure near
o Irreversible damage near
MSc Thesis W. Vos
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21.  Apply predetermined load
to bridge
o Information lacking
o Damage due to ASR, …
 Proof load testing
o Immediate approval of
bridge
o Recalculate updated β
o RC slab bridges
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22.  Europe: DAfStB Richtlinie
 Stop criteria
o Concrete strain
o Steel strain
o Crack width and residual
crack width (new & existing
cracks)
o Residual deflection
 For flexure
 Structures with large existing
cracking?
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23.  North America:
o Buildings: ACI 437.2M-13
o Bridges: Manual of Bridge
Rating Through Load Testing
(1998)
 ACI 437.2M-13 stop criteria:
o Residual deflection
o Permanency ratio
o Deviation from Linearity Index
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24.  Guideline for proof loading of existing bridges for the
Netherlands
 Flexure + shear
 Stop criteria?
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25.  Proof load tests:
o Heidijk 2007
o Medemblik 2009
o Vlijmen-Oost 2013
o Halvemaans Bridge 2014
o Ruytenschildt Bridge 2014
o Viaduct in the Zijlweg 2015
o Viaduct De Beek 2015
o Vecht Bridge 2016 Load test to failure of Ruytenschildt Bridge, summer 2014
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26.  Heidijk
o RC slab bridge
o ASR-induced damage
o Loading frame
o RWS + TNO
 Medemblik
o Girder bridge
o BELFA
o RWS + TNO + ifem
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27.  Video
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28.  BELFA
 Viaduct with ASR-damage
 Viaduct remained open to
traffic
 Disturbs AE measurements
 TU Delft + ifem:
measurements
 Bridge approved
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29.  System with load spreader
beam
 Bending moment capacity
 1 night closure of bridge
 TU Delft: measurements
 Bridge from 1930s
 Approved with proof load test
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30.  Existing reinforced concrete slab
bridge (1962)
 Test to failure in two spans
 4 concentrated load – one tandem
 Cyclic loading protocol
 Failure only achieved in span 2
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31. Existing bridge Partial demolition and building new bridge
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32. 10/28/2016 32

33.  Proof load test for bending
moment and shear
 Bridge closed for 1 week
 Viaduct over highway
 ASR-induced damage
 Approved thanks to proof
load test
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34.  No material damage
 Extensive cracking
 Proof load test on Span 1
 Span 2 over highway
 Shear and flexure position
 Bridge approved if 7% plastic
redistribution in Span 2 is OK
 Check for durability/corrosion
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35.  Video
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36.  Determination of dimensions
 Live load: EN 1991-2:2003
 RBK load levels
o Different β
o Different load factors
 In FEM model
o mx over 3 m
o v over 4d
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37.  Critical position
o Bending moment: largest
moment
o Shear: 2.5d from Support
 Required proof load
o Same shear or bending
moment as with load
combination
o Value → considered safety
level
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38.  Cyclic loading scheme
o Acoustic emission measurements
o Check linearity and reproducibility of measurements
o Check residual deformations
 Stop criteria
o Evaluated during tests
o Research in progress
o Criteria for shear failure need to be developed
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39.  Beams from Ruytenschildt Bridge
o Cyclic loading protocol
o Tests: Failure in shear and flexure
o 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)
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40. 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%
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41.  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.
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42.  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.
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43.  Use cyclic load protocol
o Study linearity and repeatability of results
 Flexure: Stop criteria exceeded long before failure
o 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:
o Need to develop stop criteria
o Research on acoustic emission measurements
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44.  Controlled experiments in
laboratory
 Heavily instrumented beams
 Beams: part of series of
shear tests
 Study of stop criteria and
loading protocol
o Interrelated!
 First proposal for stop criteria
for guideline
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45. Previously cracked in bending moment or not?
Failure mechanism Uncracked Cracked
Flexural failure Concrete strains
wmax ≤ 0.5 mm
wres ≤ 0.1 mm
Stiffness reduction ≤ 25
%
Deformation profiles
Load-displacement graph
Concrete strains
wmax ≤ 0.5 mm
wres ≤ 0.1 mm
Stiffness reduction ≤ 5 %
Deformation profiles
Load-displacement graph
Shear failure Concrete strains
wmax ≤ 0.3 mm
Stiffness reduction ≤ 5 %
Deformation profiles
Load-displacement graph
Concrete strains
Stiffness reduction ≤ 5 %
Deformation profiles
Load-displacement graph
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46. 10/28/2016 46

47.  Proof loading to approve existing
bridges
 Existing guidelines:
o Only flexure
o Cracked structures?
 Research on stop criteria
 Determination of maximum proof
load
o LFEA
o Different safety levels
 Execution
o Cyclic loading protocol
o Safely applying large loads
Viaduct Zijlweg, tested in summer 2015
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48. Contact:
Eva Lantsoght
elantsoght@usfq.edu.ec // E.O.L.Lantsoght@tudelft.nl
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