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Abstract
One of the underlying inciples of fracture mechanics is that unstable fracture occurs when the stress intensity. factor at the crack tip reaches a critical value . This value for mode I deformation and small crack tip plastic deformation is designated
Krc. Krc represents the inherent ability of a material to
withstand a given stress - field intensity at the crack tip .. and resist progressive tensile crack extension under plane strain conditions .
In the present work, the fracture behavior of concrete beams
reinforced by steel bars and steel fibers was investigated. The
effect of fiber volume fraction, notch - depth and different types
of coarse aggregate on the fracture toughness of concrete
beam specimens of dimensions 6 x 15 x 65 cm and reinforced
with different areas of steel bars were studied The used fiber
volume fraction were 0.0 and 1.0 % , the notch / depth ratios
were 0.1 , 0.3 , 0.5 and steel bars reinforcement areas were 20
6 mm and 2 0 8 mm. Two different types of coarse aggregate
used in the mIX (dolomite and gravel). The flexural strength
of unnotched beams of the same dimensions , splitting tensile
strength of standard cylinders and compressive strength of standard
cubes were measured for the considered fiber volume fraction and
for the two types of coarse aggregate mentioned above.