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Proof load testing of the viaduct De Beek

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Proof load testing can be a suitable method to show that a bridge can carry the required loads
from the code without distress. This paper addresses the preparation, execution, and analysis of a
proof load test on a four-span reinforced concrete solid slab bridge, viaduct de Beek. The bridge
has one lane in each direction, but was restricted to a single lane, since an assessment showed
that the capacity is not sufficient to allow both lanes. For this proof load test, the bridge was
heavily equipped with sensors, so that early signs of distress can be seen. The difficulty in this test
was that, for safety reasons, only the first span could be tested, but that the lowest ratings were
found in the second span. A direct approval of the viaduct by proof loading was thus not possible,
and an analysis was necessary after the field test. The result of this analysis is that only by allowing
6.7% of plastic redistribution in the second span, sufficient capacity can be demonstrated.

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Proof load testing of the viaduct De Beek

  1. 1. IABSE SYMPOSIUM ENGINEERING THE FUTURE SEPTEMBER 21-23, 2017 PROOF LOAD TESTING OF VIADUCT DE BEEK Eva Lantsoght, Rutger Koekkoek, Yuguang Yang, Cor van der Veen, Dick Hordijk, Ane de Boer
  2. 2. OVERVIEW • Introduction: load testing • Viaduct De Beek: description • Preparation of proof load test • Execution of proof load test • Assessment of viaduct De Beek Testing of Ruytenschildt Bridge
  3. 3. IABSE SYMPOSIUM ENGINEERING THE FUTURE SEPTEMBER 21-23, 2017 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. 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
  5. 5. VIADUCT DE BEEK (1) • RC slab bridge of 4 spans • Built in 1963 • Parabolic change in height • Proof load test at shear- and flexure-critical position in first span
  6. 6. VIADUCT DE BEEK (2) • Core drilling: fck = 44.5 MPa & fcd = 30 MPa • QR 24 steel (plain bars), fyk = 252 MPa • Insufficient flexural capacity • Reduction of 2 lanes to 1 lane • Lowest capacity: span 2 • But: span 2 over highway => testing not allowed for safety
  7. 7. PREPARATION OF LOAD TEST – TARGET PROOF LOAD Reliability level β Pb [kN] Ps [kN] EC ULS 4.3 1656 1525 RBK Design 4.3 1649 1516 RBK Reconstruction 3.6 1427 1311 RBK Usage 3.3 1373 1262 RBK Disapproval 3.1 1369 1257 EC SLS 1.5 1070 976 • Find target proof load that results in same sectional moment or shear as load combination of code • With LFEA • Load combination with load factors depending on safety level • Exception γDL = 1.10
  8. 8. PREPARATION OF LOAD TEST – SENSOR PLAN • Deflections in longitudinal and transverse direction • Vertical deflections at support • Strain on bottom of concrete • Opening of existing cracks • Cracking activity with acoustic emission sensors • Load cells for applied loads
  9. 9. EXECUTION OF PROOF LOAD TEST – LOADING PROTOCOL • Test for bending moment and test for shear • Cyclic loading protocol • Four load levels: • Low load to check response of all sensors • Serviceability Limit State • RBK Usage Level: maximum required for assessment • Eurocode Ultimate Limit State + 6% (bending test) / + 2% (shear test)
  10. 10. EXECUTION OF PROOF LOAD TEST – LOAD APPLICATION • Load application: counterweights on steel spreader beam; load transferred to bridge via jacks • Controlled method for cyclic loading • Avoid collapse when large deformations occur
  11. 11. EXECUTION OF PROOF LOAD TEST – VERIFICATION OF MEASUREMENTS • Load-displacement diagram: check for nonlinear behavior • Maximum stiffness reduction: • Bending moment test 16% • Shear test 10% • Residual deflection / maximum deflection • Bending moment test: 15% • Shear test: 8% • Limit ACI: 25% • Limit DAfStB: 10%
  12. 12. ASSESSMENT OF VIADUCT DE BEEK – SPAN 1 • Proof load test shows immediately that span fulfils requirements of code • No signs of distress observed from measurements • Conclusion: UC ≤ 1.0
  13. 13. ASSESSMENT OF VIADUCT DE BEEK – SPAN 2 • How to extrapolate results from Span 1 to Span 2? • Assessment with plastic redistribution • Plastic hinge develops in span 2 • Use 6.7% of plastic redistribution • UC in span = 1.0 • UC over support 0.94
  14. 14. ASSESSMENT OF VIADUCT DE BEEK - RECOMMENDATIONS • Verify reinforcement in Span 2 with scanner and/or by removing cover • Check for signs of corrosion • Reopen for two lanes of traffic
  15. 15. IABSE SYMPOSIUM ENGINEERING THE FUTURE SEPTEMBER 21-23, 2017 SUMMARY • Proof load testing to approve existing bridges • Case study: Viaduct De Beek • Preparation of load test: • Target proof load • Sensor plan • Execution of load test • Cyclic loading protocol • Jacks and steel spreader beam • Real-time evaluation of measurements • Analysis of load test • Assessment of viaduct • Reporting all results
  16. 16. Contact: Eva Lantsoght E.O.L.Lantsoght@tudelft.nl // elantsoght@usfq.edu.ec +31(0)152787449

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