Challenge the future

Delft University of Technology

Proof load testing in the Netherlands

Eva Lantsoght

Overview of current research

2

Overview

• Introduction • Why proof loading?

• Existing guidelines?

• 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

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

Safety philosphy of proof load testing

• Safety philosophy • Stop criteria:

• Further loading not permitted

• Failure near

• Irreversible damage near

MSc Thesis W. Vos

5

Existing Guidelines for proof loading

• Europe: DAfStB Richtlinie • Originally derived for

buildings • Plain and reinforced

concrete • For flexure

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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: • Proof load testing load

combination

• Acceptance criteria for

flexure

• Cyclic loading protocol

7

Research need

• Guideline for proof loading of existing RC slab bridges for the Netherlands

• Flexure + shear

• Measurements? Target proof load?

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TU 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

Load test to failure of Ruytenschildt Bridge, summer 2014

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Beam tests

• 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)

10

Preparation steps (1)

• Preliminary inspection and rating

• Determination of dimensions • Live load: EN 1991-2:2003 • RBK load levels

• Different β • Different load factors

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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

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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)

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Execution steps (1)

• Cyclic loading scheme • Acoustic emission measurements

• Check linearity and reproducibility of measurements

• Check residual deformations => no non-linearity

• Load levels ≈ safety levels CC3 RBK:

• Low level to check instrumentation

• SLS

• Intermediate level

• Target proof load

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Execution steps (2)

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Analysis Steps (1)

• Data analysis • Correct for T

• Correct for support

displacements

• Make final plots for report

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Discussion and future research

• Minimum measurements • “Quick and easy” method

for practice • Improvement of stop criteria

for shear

• Draft guidelines submitted to RWS in December

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Summary and conclusions

• Proof loading to approve existing bridges, also for shear

• Pilot proof load tests in the Netherlands + beam tests

• Current recommendations • First draft guidelines for practice

submitted

Viaduct Zijlweg

18

Contact:

Eva Lantsoght

E.O.L.Lantsoght@tudelft.nl // elantsoght@usfq.edu.ec

+31(0)152787449