Effects of mix variables and distributions of steel bars on fracture behaviour of R.C.beams

Many reinforced concrete structures failed due to thepresence of microcracks which lead to localized stressconcentrations, which in turn lead to failure of concretemembers under loads below the design values. consequently,many researches developed in the field of fracture mechanicsto study the effect of such stress and displacement fields inthe crack tip region and the effects of flaws on themechanical behavior of materials, and thus preventingunexpected failures of concrete members.In the present work, the fracture behavior of plain andreinforced concrete beam specimens under one-point loading atthe mid-span was investigated. The effects of nominal maximumsize of gravel, crack-depth ratio and distribution of thetension steel reinforcement through the width of the beam forthe same area of steel on the fracture toughness of notched(artificial crack) concrete beam specimens of dimensions 10 *18 * 80 cm were studied. The nominal maximum sizes of gravelstudied were 10, 14, and 20 mm, the crack depth ratios were0.3, 0.5, and 0.6 and the tension reinforcement were 2~10,3~8, and 5~6 mm to maintain the same steel area. A theoreticalfracture mechanics model was used and the predicted valuesfrom it were compared with the experimental results obtained.It was found that plain concretewhen the applied stress intensity factor