EFFECT OF VERTICAL RECTANGULAR OPENINGS ON TiHE FLEXURAL STRENGTH OF REINFORCED CONCRETE BEAM
ABSTRACT
Effect of vertical rectangular openings on the flexural strength of reinforced concrete beam is presented. Twelve reinforced concrete beams of dimension 200m x 230mm x 700mm with different sizes of rectangular openings, 25mm x 35mm, 50mm x 60mm and 75mm x 85mm which are placed at 150 mm from the supports, were cast. After curing, these beams were tested under centre-point loading system using universal testing machine and the flexural strength were determined. The results show that the flexural strength of the beams reduces gradually with the increase in the sizes openings. The optimum flexural strength was 13.47 N/mm2 with opening size of 25mm x 35mm, also the maximum deflection was 14.19 mm, which do not exceed 20 mm allowable deflection provided by BS 8110. Hence, it is hereby recommended that introduction of vertical rectangular openings on reinforced concrete beam should not exceed potions of 150 mm from the supports and openings of 75mm x 85mm sizes.