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Hokkaido Univ. Tamura Hiroya

Effect of Adhesive Thickness on Bond Behavior of Carbon Fiber Sheet under Static and Fatigue Load. Hokkaido Univ. Tamura Hiroya. The outline of the study. ・ adhesive thickness is controlled by conditions at the surface concrete.

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Hokkaido Univ. Tamura Hiroya

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  1. Effect of Adhesive Thickness on Bond Behavior of Carbon Fiber Sheet under Static and Fatigue Load Hokkaido Univ.Tamura Hiroya

  2. The outline of the study ・adhesive thickness is controlled by conditions at the surface concrete. ・the few studies of adhesion characteristics in cyclic loading. Background Object To get deeper insight into the effect of varying adhesive thickness under static and fatigue loading.

  3. Experimental Property specimen fatigue static concrete sheet property resin property

  4. 60 400 400 100 60 50 200 150 unbonded area 100 Specimen style attaching work ② pouring resin ① making divider ③ attaching CFS

  5. Beam Distributing Load specimen 855 Hinge H steel 600 1200 Test Equipment Equipment prepared according to Osaka University’s bending machine test setup advantage • To cancel out • bending moment on sheet • To be easy to calculate working pull out strength on sheet

  6. Static Test Result • Increasing with adhesive thickness Pullout Strength • The rate of increase step down Dai et al.’s model Correspond This is experimental formula the function of resin thickness

  7. Static Test Result Pullout strength is increasing with adhesive thickness Why correlation? Thickness increase thickness 0.2mm Effective bond length increase Local bond stress decrease Pullout strength increase thickness 2mm

  8. Definition - Effective Bond Length 100% line 5% line sheet stress distribution Bond stress distribution It is considered that 5% of maximum bond stress is active The effective bond length is 90mm

  9. Effective Bond Length Pattern like pull out strength Effective bond length is very different between 0.2mm specimens and the others.

  10. Fatigue Test Result – fatigue life In fatigue loading level Fatigue life decrease with adhesive thickness 1mm and 3mm specimens are extremely low, compare to 0.2mm specimens. In fatigue loading The fatigue life is closing each other as fatigue life decrease. 0.2mm specimen’sfatigue life that is lower than 22kN is the longest

  11. Fatigue Test Result－ effective bond length In static test The specimen of 0.2mm thick are lower effective bond length than the other. t = 0.2mm Static test Static test Fatigue test In fatigue test Effective bond lengths of 0.2 mm specimens increase therefore Fatigue life of 0.2mm specimen get to be long Fatigue test

  12. Conclusion 1 n the static test, the pullout bond strength increased with the adhesive thickness because the effective bond length increased. 2 The effects of adhesive thickness were as predicted by Dai et al’s model. 3 In the fatigue test, the fatigue life in the case of 0.2 mm adhesive thickness became longer because the effective bond length became longer in comparison with the thicker adhesive cases.

  13. Thank you for your kind attention

  14. Breaking pattern thickness 0.2mm thickness 1～3mm Thick resin causes to break on resin layer, not concrete surface. Capability that difference in thickness may be the reason of the result in fatigue.

  15. Breaking pattern Thickness 3mm thickness 0.2mm Thickness 3mm

  16. Object of Pretest for master thesis Steel slab is reinforced by UFC Both Steel and UFC have high strength, therefore can design by only two value, adhesive thickness and elastic modules. I choose adhesive thickness as the experimental value to Compare to graduation thesis Constitutive law of adhesion of different material (FRP-concrete, UFC-steel)

  17. UFC is … material cement water fine aggregate Steel fiber Silica fume Silicate sand High strength High density Compressive strength is x5 Tensile strength is x3 Dispersion of crack High durability against… • chemical attack • Salt attack • Freezing and thawing This property can avoid brittle failure

  18. 60 400 400 UFC Steel formed H Polystyrene 50 140 10 200 100 The way of control adhesive thickness Polystyrene is used to encircle the area to be bonded to the intended adhesive thickness

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