Abstract

Contractors occasionally substitute reinforcement bars during construction works, perhaps as a result of unavailability of the design-specified bars. As a result, this study have explored the basis, extent and the conditions for the mutual substitution of reinforcing bar groups of equivalent area but different bar diameters in reinforced concrete beams. A total of (20) concrete beams including the control beams were cast. These comprise (2) each of 100 mm×100 mm×500 mm and 150 mm×150 mm×750 mm beams as plain concrete (control beams) and (2) each of 100 mm×100 mm×500 mm and 150 mm×150 mm×750 mm beams were reinforced in turn with 20 mm, 16 mm, 12 mm and 10 mm bar diameters. The beams were subjected to centre-point loading using bending testing machine, in accordance with BS 1881-118 and with the load and compressive strain recorded to the point of failure. The results of the test beams showed that the greatest difference in the area of reinforcement between beams reinforced with 9Y12 bars (bar area = 1020 mm2) and 3Y20 bars (bar area = 943 mm2) is 7.5%. The results also showed that given the same area of steel in a cross section, the section with the greater number of bars has higher bending strength. It was also deduced that an increase in the area of reinforcement would cause a disproportionate increase in the strength of the beam.

Keywords:

Bending, concrete beams, flexural strength, plain concrete, reinforcement,

References

Competing interests

The authors have no competing interests.

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The authors have no competing interests.