EXPERIMENTAL STUDY ON DIAGONAL COMPRESSION FAILURE OF RC BEAMS USING HIGH-STRENGTH CONCRETE

1. EXPERIMENTAL STUDY ON DIAGONAL COMPRESSION FAILURE OF RC BEAMS USING HIGH-STRENGTH CONCRETE Chikaharu KOBAYASHI Tokyo Institute of Technology Ken WATANABE Tokyo Institute of Technology Junichiro NIWA Tokyo Institute of Technology Thank you for your kind introduction. My name is Chikaharu KOBAYASHI from Tokyo Institute of Technology. I would like to talk about experimental study on diagonal compression failure of RC beams using high-strength concrete.Thank you for your kind introduction. My name is Chikaharu KOBAYASHI from Tokyo Institute of Technology. I would like to talk about experimental study on diagonal compression failure of RC beams using high-strength concrete.

2. 2 Recently, high-strength and high-performance concrete and steel have been developed. For example, as for concrete high strength concrete which has a compressive strength of more than 60mpa, in the steel high strength steel which has yield strength of more than 700MPa. In order to make use of this material advantage and make RC structures economically, RC members are made thin-walled and dense shear reinforced. In this structure, ultimate capacity for diagonal compression failure decrease. Because of these factors, accurate calculation of load carrying capacity for diagonal compression failure in RC beams using the high-strength concrete is needed.Recently, high-strength and high-performance concrete and steel have been developed. For example, as for concrete high strength concrete which has a compressive strength of more than 60mpa, in the steel high strength steel which has yield strength of more than 700MPa. In order to make use of this material advantage and make RC structures economically, RC members are made thin-walled and dense shear reinforced. In this structure, ultimate capacity for diagonal compression failure decrease. Because of these factors, accurate calculation of load carrying capacity for diagonal compression failure in RC beams using the high-strength concrete is needed.

3. 3 Background On the other hand, although the equation was proposed like this, this diagonal compression failure is not yet fully understood because of the lack of sufficient research in this failure. For that reason, JSCE propose a quite conservative equation for safety reasons. Past researches covered only normal strength concrete. This equation is covered only for concretes not exceeding 50MPa in compressive strength of concrete. From these backgrounds, this research objective is to clarify characteristics of the diagonal compression failure in RC beams using high-strength concrete.On the other hand, although the equation was proposed like this, this diagonal compression failure is not yet fully understood because of the lack of sufficient research in this failure. For that reason, JSCE propose a quite conservative equation for safety reasons. Past researches covered only normal strength concrete. This equation is covered only for concretes not exceeding 50MPa in compressive strength of concrete. From these backgrounds, this research objective is to clarify characteristics of the diagonal compression failure in RC beams using high-strength concrete.

4. 4 Objective

5. 5 Outline of Specimens All specimens were designed to fail in the diagonal compression failure: each specimen has high-strength bars as a longitudinal reinforcement against flexural capacity. Stirrups consisted of high-strength bars and were closely arranged against diagonal tension failure. All specimens were designed to fail in the diagonal compression failure: each specimen has high-strength bars as a longitudinal reinforcement against flexural capacity. Stirrups consisted of high-strength bars and were closely arranged against diagonal tension failure.

6. 6 Load-Displacement Curves

7. 7 Accuracy of Prediction Equation by Placas et al.

8. 8 Influence of Compressive Strength of Concrete

9. 9 Accuracy of Evaluation of rw

10. 10 Influence of Spacing of Stirrups

11. 11 Load-Displacement Curves

12. 12 Under the same condition except for nominal diameter of stirrups and spacing of stirrup, the specimen which have narrow spacing of stirrup crushed more widely in shear span and got larger capacity. Under the same condition except for nominal diameter of stirrups and spacing of stirrup, the specimen which have narrow spacing of stirrup crushed more widely in shear span and got larger capacity.

13. 13 Dependence of rw or s?

14. 14 Conclusions

15. Thank you for kind attention!

16. 16 Effect of a/d

17. 17 Influence of a/d

18. 18

19. 19 Accuracy of Prediction Equation by JSCE