Bridge Deck-Guardrail Anchorage Detailing For Sustainable Construction


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Application to use GFRP bar as for bents bars and headed bars in bridges

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Bridge Deck-Guardrail Anchorage Detailing For Sustainable Construction

  1. 1. Bridge Deck-Guardrail Anchorage Detailing For Sustainable Construction<br />Khaled Sennah, NavidNikravan, Jacob Louie, Adam Hassan, Nabil Al-Bayati, Mohamed El-Sayed, and MahmoudSayed-Ahmed<br />1<br />
  2. 2. Table of Content<br />Introduction<br />The problem (Post/Deck)<br />Materials<br />ComBAR Bent Bars<br />ComBAR Headed Bars<br />Post Anchor<br />Research Approach<br />Failure Modes<br />Test Results<br />Conclusions<br />Acknowledgements<br />2<br />
  3. 3. Introduction<br />The Residential and Civil Construction Alliance of Ontario, Canada, (RCCAO) released a report on the state of Ontario bridges, entitled “Ontario’s Bridges: Bridging the Gap.” <br />Glass Fiber Reinforced Polymer (GFRP) provides high tensile strength (1100 Mpa) with ribbed surface to ensure optimal bond between concrete and the bar.<br />3<br />
  4. 4. Cont.<br />The Canadian Highway Bridge Design Code, CHBDC, (CAN/CSA-S6-2006) allows the use of GFRP bent bars in bridges. CHBDC Chapter 16: Fibre Reinforced Structures specified empirical equations to determine the development length of the GFRP bars with straight ends, with no mention of GFRP bars with headed-ends or GFRP stirrups.<br />4<br />
  5. 5. Cont.<br />CHBDC Clause stated that the suitability of a traffic barrier anchorage shall be based on its performance during crash testing. the anchorage and deck shall be designed to resist the maximum bending, shear and punching loads that can be transmitted to them by the traffic barrier resulting from a factored lateral force of 170 kN applied near the top of the barrier wall and distributed over a length of 1050 mm of the traffic barrier length.<br />5<br />
  6. 6. Typical Bridge Cross Section<br />Replacement of deck slab cantilever with the steel guardrail post<br />6<br />
  7. 7. The problem<br />Developed GFRP bent bars was proposed to be used in one of new bridges in Ontario, to work as stirrups at the joint between steel post and the reinforced concrete cantilever slab deck.<br />Two full scale post/deck specimens were erected and tested to-collapse.<br />7<br />
  8. 8. Materials<br />ComBAR Bent Bars & Stirrups<br />ComBAR Headed Bars<br />Post Anchorage<br />8<br />
  9. 9. ComBAR Bent Bars & Stirrups<br />A bending diameter of seven times the bar core diameter (df) has proven to be a good compromise between strength and usability <br />9<br />
  10. 10. Cont.,<br />Material Properties<br />Longitudinal section through a stirrup with bending diameter 7 df<br />10<br />
  11. 11. ComBAR Headed Bar<br />The maximum outer diameter of the heads is 2.5 times the diameter of the bar. The used head of the 16 mm bar is approx. 100 mm long.<br />11<br />
  12. 12. Post Anchorage<br />AASHTO Specification for guardrails<br />12<br />
  13. 13. Research Approach<br />Investigation for the joint between steel post of the bridge guard-rail system and the slab cantilever.<br />Two full scale cantilever post specimens were erected and then tested to-collapse.<br />Lateral Load was applied to the steel post at 790 mm from the top surface of the concrete slab.<br />Lateral and Vertical displacements were recorded. <br />13<br />
  14. 14. Steel reinforcing bar specimen<br />14<br />
  15. 15. GFRP reinforcing bar specimen<br />15<br />
  16. 16. 16<br />
  17. 17. Test<br />17<br />
  18. 18. Failure Modes<br />Steel / Material Failure (shear)<br />Concrete side-face blowout <br />Concrete Breakout (shear)<br />Pryout (shear)<br />18<br />
  19. 19. Cont.<br />Modes of failure of steel anchors under shear load in concrete (Source: fischer)<br />19<br />
  20. 20. Cont.<br />Intersection of the break-out bodies of anchors under shear load close to an edge<br />(h ≧ 1.5 c1)<br />20<br />
  21. 21. Test Result<br />Five concrete cylinders were tested in axial compression.<br />All specimen exhibited first crack starting near the rear corner of the base plate.<br />Cracks propagates towards the bottom tip of front face of curb, widened to concrete cover, to spall (breakout).<br />Minor cracks appeared at the rear end of anchor in tension and the inner edge of curb (pryout).<br />21<br />
  22. 22. Cont.<br />22<br />Concrete Compressive Strength is 34.27 MPa<br />First Crack at 80 kN<br />Failure at 151.76 kN<br />
  23. 23. Cont.<br />23<br />Concrete Compressive Strength is 32.87 Mpa<br />First Crack at 90 kN<br />Failure at 169.11 kN<br />
  24. 24. Cont.<br />24<br />
  25. 25. Conclusions<br />GFRP-reinforced specimen is as good as the steel-rienforced specimen.<br />Primary failure is due to combined torsion and direct compression resulting from the compressive stresses at the outer portion of the post steel base plate (concrete side-face blowout & breakout).<br />25<br />
  26. 26. Acknowledgments<br />The Authors acknowledge the following industry collaborators: <br />Ryerson Undergraduate Research Opportunities (URO) Scholars Program, <br />Schoek Canada Inc., <br />McCormick Rankin Corporation <br />Infrastructure Canada. <br />26<br />
  27. 27. 27<br />