ABSTRACT

This research studied the effect of the number of pre-tensioned wires on the flexural capacity of a rectangular concrete beam. Pre-stressed technology enhance the overall flexural capacity of concrete over a longer without increase in cross-sectional dimension The technology allows for longer spans, reduced structural thicknesses, and saves material as compared with reinforced concrete technology. Different number of pre-tensioned 3.0mm diameter high strength steel tendons were used in this study ranging from 4 to 8 numbers of concentrically placed tendons, then 3 number of eccentrically placed tendons which were compared with non – pre-tensioned concrete beam. The results indicated that the highest value of flexural capacity of 9.16N/mm2 was obtained from the beam with the highest number of tendons. It is also indicated from this study that when there is an increase in the number of concentrically placed pre-tensioned tendons from 0No of tendons to 4No, there is a 74.82% increase in the flexural strength of the concrete beam. Also when there is an increase in the number of concentrically placed pre-tensioned tendons from 4No to 6No, there is a 10.87% increase in the flexural strength of the concrete beam, and when there is an increase in the number of concentrically placed pre-tensioned tendons from 6No to 8No, there is a 12.25% increase in the flexural strength of the concrete beam.

The results also indicates that beams with eccentrically placed tendons yields higher flexural capacity when compared to beams with concentrically placed tendons.

Keyword: Pre-tensioned tendons, Flexural capacity, concentric tendons, Eccentric tendons, Compressive strength.