FRACTURE BEHAVIOR OF REINFORCED CONCRETE FLANGED BEAMS UNDER FOUR POINT BENDING INDISPLACEMENT CONTROLLED ENVIRONMENT

Abstract

A four point bend test in a displacement controlled environment is used to investigate the fracture behavior of the T- shaped reinforced concrete beams. Two parameters were investigated: the ratio of flange width to web width (Bib) and the ratio of flange thickness to beam's height (t/h). The testing program comprises 12 beams; 3 having rectangular section and 9 having T-section. All beams are 1400 mmin length with a mid span height of300 mm and a mid span

notch of 90 mm. The beams are classified into 3 groups. In the-first group, the tested beams have variable flange width to web thickness (Bib):1, 1.5, 2, 2.5, constant ratio of flange thickness to beam height (t/h) =0.2 and a reinforcement ratio=0.6%. The second group of beams has variable flange width to web thickness (B/b):1, 1.5, 2, 2.5, constant ratio of flange thickness to beam height (t/h) =0.15 and a reinforcement ratio 0.48%. The third group of beams has variable flange thickness to beam height (t/h):O, 0.1, 0.15, 0.2, constant ratio of flange width to web thickness (Bib) =1.5 and a reinforcement ratio 0.73%. Measurements included load, steel strain, concrete strain and

deflection. Tracking for the mid span crack at each load increment was carried out. The analytical model proposed by Baluch et al. was employed. The experimental results were checked against the new fracture mechanics approach. Also, the experimental results were compared to the results of a finite element program. However, the experimental program revealed that the ratio of flange width to web width (B/b) is more effective than the ratio of flange thickness to beam's height (t/h). In addition to that, both the fracture mechanics