1. 4th November 2005 Towards Unified Bond Modelling for the Structural Behaviour of GFRP-RC Kypros Pilakoutas Harsha Sooriyaararachchi Maurizio Guadagnini Centre for Cement and Concrete Department of Civil and Structural Engineering, University of Sheffield, Sheffield, United Kingdom

2. 4th November 2005 GFRP bars Use of GFRP for bridge deck construction (Franklin county bridge Virginia) Stiffness of GFRP compared to Steel GFRP-RC in Construction

3. 4th November 2005 Outline Hierarchy of bond modelling Macro level Modelling Meso level modelling Average bond stress slip relation Formulation of bond modelling using strain distribution Local bond stress-slip-strain relation  s 

4. 4th November 2005 Steel reinforcementFRP reinforcement Hierarchy of bond Modelling Macro-level modelling

5. 4th November 2005 Steel reinforcementFRP reinforcement Macro-level modelling Hierarchy of bond Modelling Meso-level modelling

6. 4th November 2005 Steel reinforcementFRP reinforcement Macro-level modelling Meso-level modelling Micro-level modelling Hierarchy of bond Modelling

7. 4th November 2005 Tension stiffening effect Bare bar response RC response Tension stiffening of concrete is defined as: the ability of concrete to carry tension between cracks and provide extra stiffness for RC in tension. Macro Level Bond Modelling

8. 4th November 2005 Test results bar stress Vs overall strain Average stress strain behaviour of concrete Strain Softening Behaviour Concrete

9. 4th November 2005 Reinforced concrete in tension Typical Test Results Strain of the composite specimen at Strain of the bar at crack Average Strain Average Stress Stage I Pre Cracking Stage II Crack Propagation Stage III Post Cracking Response of composite section Bare bar response Tension Stiffening Behaviour

10. 4th November 2005 1 st crack 2 nd 3 rd Internally strain gauged bar Strain Distribution while Cracking Stage I Stage II

11. 4th November 2005 Post cracking slip and strain Stage III

12. 4th November 2005 Typical strain and bond stress distribution between cracks Strain and bond between cracks

13. 4th November 2005 Meso Level Bond Modelling Direct tension test Pullout test Magnified images showing bond failure

14. 4th November 2005 Average Bond Stress Vs. Slip (a) (d) (b) (c) Comparison of average bond stress slip behaviour for the two test in almost identical circumstances 50%

15. 4th November 2005 Stress Conditions During Testing Direct tension test Pull out test

16. 4th November 2005 Bond Stress based on strain distribution Strain Distance between cracks Strain Distance along the embedment length

17. 4th November 2005 Local Bond Stress Slip Relationship 0 25 50 75 100150 175 125 0 25 50 75 100150125

18. 4th November 2005 x ss

19. Bond stresses slip at different strain

20. 4th November 2005 S cal = Slip at peak bond stress at calibrated strain  cal = Referred strain for calibration  s  Relation for BOND

21. 4th November 2005 Comparison of Results

22. 4th November 2005 Local Bond Stresses in Pull-out 5D Grade 90 Grade 45

23. 4th November 2005 Local Bond Stresses in Pull-out 10D Grade 90 Grade 45

24. 4th November 2005 Comparisons of results Local bond behaviour in pull out test 19/45/10D

25. 4th November 2005 Conclusions  - s -  approach proposed Is Average bond stress slip relationship useful? Different levels of bond modelling More work to be done Bond stress profile changes with increasing load Testing conditions affect bond behaviour