Issue34

I. Ivanova et alii, Frattura ed Integrità Strutturale, 34 (2015) 90-98; DOI: 10.3221/IGF-ESIS.34.09 96 Influence of cyclic load on strengthened reinforced concrete corbels behavior Two strengthened reinforced concrete corbels are tested in static and dynamic loads. The failure load of strengthened reinforced concrete corbel after one million cycles, was 584 kN with fatigue test and 651 kN with static test. That was 11 % less than reinforced concrete corbel under a simple bending test. The carbon fiber fabrics included the strain of structures about 400.10 -6 while the steel bar is deformed less than 200.10 -6 as shown in Fig. 6. The appearance of bearing at 365 kN physically characterized by diagonal and deformations reached at 600.10 -6 . The carbon fibre fabrics have resumed strain of structure. The strain of steel tie at mounting section is relatively small in the range of 100.10 -6 as shown in Fig. 6. The strain at point G1 pulling close cross section where strains are highest. Deformations are sufficient to cause the disorder in the structure. The investigating did not show failure of carbon fabrics. The strain of carbon fibres fabrics at point GC1, the same position like G1, at least 400.10 -6 between in Fig. 6 of 900.10 -6 to 1300.10 -6 , is insufficient to generate cracks in strengthened reinforced concrete corbel. Cracking and mode of failure Fig. 7 shows two reinforced concrete corbels "C0" (Fig. 7 a) and "C0 fatigue" (Fig. 7 b). The first one is tested up to failure without fatigue and the second one is tested after one million cycles in bending load to collapse. The results showed a new crack is appeared after fatigue testing. Many apparent cracks are showed on reinforced concrete corbel. The difference is depending on the type of loading. Their propagations are different into static tests which proves the fatigue effect with the appearance of a diagonal crack in the concrete column, see Fig. 7b. a) "C0" static test without fatigue b) "C0" static test after fatigue Figure 7 : Cracking and failure of reinforced concrete corbel: a) C0 - static loading to failure, b) C0 fatigue - after one million cycles of unreinforced concrete corbel. The results show in Fig. 8, the cracking and failure modes of strengthened reinforced concrete corbels. After static test, the specimen ruptured in shearing and splitting failures Fig. 8a. Strengthened corbel after one million cycles has no visible cracks, when the corbel is strengthened by wrapping, Fig. 8b. In fact, the results show the same failure cracks as CB3u static test. C ONCLUSION his study focused on the strengthening of reinforced concrete short corbel bonded by composite carbon fiber fabrics. Particularly, this paper investigates the effect of damaged fatigue test of strengthened structure. So, this influence of fatigue damage on mechanical behavior and durability of strengthened reinforced concrete corbel under three-point bending test are examined. The adhesion is assumed to be perfect for this type of loading, fatigue is T