Effect of Mode of Continuity of Tension Reinforcement Bars on Flexural Strength of R.C. Beam

Abstract The research investigation was carried out to determine the effect of different modes of continuity of tension reinforcement bars on the flexural strength of reinforced concrete beams. Nine (9) full size beams (2150 mm × 250 mm × 180 mm) were cast with 2 numbers of 16 mm diameter high yield bars in tension and 10 mm diameter high yield stirrups at 100 mm centres at the shear spans. Three (3) beams each were cast with full length bars (reference), lap-spliced bars and butt-welded reinforcement bars in tension. Twenty-seven (27) 150 mm cubes were also cast to monitor concrete strength. The beams and cubes were cured for twenty-eight (28) days and tested in flexure under four points bending system and in compression respectively. The test results showed that full length bars, lap-spliced and butt-welded bars had an average moment capacity of 25.54 kN·m, 19.16 kN·m and 10.64 kN·m respectively. Lap-spliced beam gave a higher moment of resistance compared to the beams with butt welded steel reinforcing bars. The average midspan deflection of butt welded reinforcement was smaller than that of in the beam with lap spliced type of continuity. It was concluded that continuity using lap spliced bars in tension is more effective and efficient than butt welded continuity. 58.34 %, 25.00 % of the moment capacity of beams with full length reinforcement was lost by using butt weld, without a coupler, and lap spliced bars, respectively.