Proposed stop criteria for proof load testing of concrete bridges and verification
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1) The document proposes stop criteria for proof load testing of concrete bridges to determine if the structure can withstand increased live loads without irreversible damage. 2) The proposed stop criteria include limits on concrete strain, crack width, residual deflection, load-deflection behavior, and bending moment and shear capacity. 3) Field tests of instrumented bridges found the structures did not exceed the proposed strain, crack width, deflection, or load criteria when subjected to proof loads, validating the proposed stop criteria. However, more shear tests are needed, especially on concrete slabs.
Proposed stop criteria for proof load testing of concrete bridges and verification
- 1. Challenge the future Delft University of Technology Proposed stop criteria for proof load testing of concrete bridges and verification Eva Lantsoght, Cor van der Veen, Dick Hordijk
- 2. 2 Overview • Introduction to proof load testing • Proposed of stop criteria • Overview • Theoretical bases • Verification • Proof load tests • Failure tests • Summary & Conclusions Slab shear experiments, TU Delft
- 3. 3 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
- 4. 4 Proof load testing • Target load • Stop criteria: • No further loading • Failure near • Irreversible damage near • Bending moment AND shear? MSc Thesis W. Vos
- 5. 5 Existing Guidelines for proof loading • DAfStB Richtlinie • Stop criteria • Concrete strain • Steel strain • Crack width and residual • Residual deflection • Flexure • Buildings • Strain: arbitrary limit • Crack width: durability
- 6. 6 Existing Guidelines for proof loading • ACI 437.2M-13 • Stop criteria: • Residual deflection • Permanency ratio • Deviation from Linearity Index • For prescribed loading protocol
- 7. 7 Proposed stop criteria (1)
- 8. 8 Proposed stop criteria (2) • Bending moment & shear • Cracked & Uncracked • w ≥ 0,05 mm • Quant & qual • ΔEI ≤ 25% • Deflection profiles • Load-deflection graph
- 9. 9 Proposed stop criteria – Bending moment • εstop ~ 0.65fy • wstop ~ 0.65fy , ,max 0c c bot c stop 2 2 0.65 2 2 ym perm stop fr c s f f s w d E
- 10. 10 Proposed stop criteria – Shear • εstop : 800με or limit CSDT (K. Benitez) • wstop: % of wai: aggregate interlock lower than inclined cracking load Aggregate interlock across crack
- 11. 11 Pilot proof load tests • Vlijmen-Oost (with BELFA) • effect of ASR • Halvemaans Bridge • flexure-critical • Zijlweg • effect of ASR • De Beek • flexure-critical • insufficient reinforcement Halvemaans Bridge
- 12. 12 Failure tests • Ruytenschildt Bridge • tested to failure in 2 spans • Beams • from Ruytenschildt Bridge • cast in lab (plain bars) Ruytenschildt Bridge with loading in span 2
- 13. 13 Verification – field tests (1) • Field tests • heavily instrumented • no structural distress • Stop criteria should not be exceeded Viaduct De Beek
- 14. 14 Verification – field tests (2) Test ε w S LD TD Vlijmen - bending >Fmax >Fmax >Fmax >Fmax -- Vlijmen – shear >Fmax >Fmax >Fmax >Fmax -- Halvemaans Bridge >Fmax >Fmax >Fmax Fmax >Fmax Zijlweg – bending >Fmax >Fmax >Fmax >Fmax >Fmax Zijlweg – shear >Fmax >Fmax >Fmax >Fmax >Fmax De Beek – bending >Fmax >Fmax >Fmax >Fmax >Fmax De Beek – shear >Fmax Fmax >Fmax >Fmax >Fmax
- 15. 15 Verification – failure tests (1) • Margin of safety • Need cyclic loading • Ruytenschildt: • span 1: no failure • span 2: pier settlement • Results: • 46% - 56% of Fmax in experiments • 62% - 65% for RSBridge Failure of P804A2
- 16. 16 Verification – failure tests (2) Test Case ε w S LD TD RB Span 1 B + C >Fmax >Fmax 63% 62% 62% RB Span 2 B + C 85% 93% 79% 65% 65% ε w S HD VD RSB01F B + UC 53% 53% 28% - 99%‡ 54% 54% RSB02A B + UC 46% 53% >Fmax 47% 47% RSB02B B + UC 62% 64% 42% - Fmax 54% 54% RSB03F B + UC 60% 62% 40% 56% 56% RSB03A S + UC 83% 81% 55% NA 55% P804A1 B + UC 52% 56% 58% 58% 77% P804A2 S + C 52% 65% >Fmax 87% >Fmax P804B S + UC 57% 88% 89% 56% 56% P502A2 B + C 81% 52% Fmax 83% 83%
- 17. 17 Summary & Conclusions • Proof load =direct assessment • Proposal stop criteria ~ Theory • Flexural theory • CSDT • Verification of criteria • Field test: not exceeded: OK • Failure tests: margin of safety • But: more shear tests (+ on slabs) necessary for validation
- 18. 18 Contact: Eva Lantsoght E.O.L.Lantsoght@tudelft.nl // elantsoght@usfq.edu.ec +31(0)152787449