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Assessment of slab bridges through proof Assessment of slab bridges through proof loading in the Netherlandsloading in the NetherlandsEva Lantsoght, Cor van der Veen, Ane de Boer, Dick Hordijk
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 conclusionsSlab shear experiments, TU Delft
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
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
Research needResearch needResearch needResearch need
Guideline for proof loading of existing (RC slab) bridges for the Netherlands
Flexure + shear
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
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)
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
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
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)
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
Execution steps (2)Execution steps (2)
Execution steps (3)Execution steps (3)Execution steps (3)Execution steps (3)
Analysis StepsAnalysis Steps
• Data analysis•Correct for T•Correct for support displacements•Make final plots for report
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
