الفهرس 
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Abstract
The idea of providing hollow section to reinforced concrete beam is
required nowadays for satisfaction requirements of placing ventilation,
concealing mechanical or electrical runs, as well as reducing self-weight
and construction costs.
The reduction of the cross.section area of the beam will effect on its
behavior in bending moment and shear resistance therefore, the
experimental testing was necessary in order to identify the flexural
strength, shear strength, deflection profile and crack pattern of the hollow
reinforced concrete beams and how to optimize their behavior.
. A total of 18 tested reinforced concrete beams were investigated
experimentally divided to five groups, all tested beams have same
dimensions with 2500mm total span length, 2250mm effective span from
support to support and same cross section of 200mm width and 300mm
thickness. First group includes two solid control beams with different
flexural Reinforcement ratio (under reinforced section to study flexural
behavior) and (over reinforced section to study shear behavior), second
group includes four hollow beams with (50mm) PVC pipes their centers
at a distance 160mm (O.58*d) from the top edge of the beam, third group
includes the same four hollow beams with (50mm) PVC pipes but their
centers at a distance 180mm (O.65*d) from the top edge of the beam,
fourth group includes four hollow beams with (75mm) PVC pipes their
centers at a distance 160mm (O.58*d) from the top edge of the beam and
fifth group includes the same four hollow beams with (75mm) PVC
pipes but their center at a distance 180mm(O.65*d) from the top edge of
the beam. For groups 2, 3, 4, and 5, half of their beams are without steel
fiber and the second half have 0.75% steel fiber content.