Novel Torsional Reinforcement of Concrete Beams Utilizing Cross-Rod Steel Reinforcement

Abstract

External strengthening of reinforced-concrete beams is challenging because of the building system complexity or the beam geometry. The major challenge is choosing an appropriate strengthening method to overcome its low torsion strength. Therefore, the main objective of this research is to ascertain how likely it is to suggest or adopt a particular internal in-plane approach to increase the torsional strength. In the present paper, the concept (technique) of adding internal concrete cross-rods (CR) in a transverse direction is adopted. Five concrete beam specimens with 200-, 200-, and 1500-mm dimensions for width, depth, and length, respectively, were poured and tested. One was a reference beam(B-R) without enhancement, while the other four (B-3CR, B-5CR, B-7CR, and B-9CR) were enhanced with three, five, seven, and nine internal cross-rod, respectively. The compressive strength of the concrete was (35MPa) at (28) days (normal strength concrete). This research intends to show how internal cross-rods (CR) and their number affect torsional capability. The experimental findings revealed significant improvements in the ultimate torsion strength capability by about 11.65%, 18.95%, 21.24%, and 27.77%, respectively, compared to the reference beam. The ultimate twisting angle and reinforced beams’ toughness increased by (4.25%-28.36%) and (24.12%-94.48%), respectively, due to the increase in the number of internal cross-rods compared to the reference beam. It was concluded that interior cross-rods would enhance the torsional strength capacity of the reinforced concrete beams. The extent of enhancement depended mainly on the number of internal cross-rods (CR) deployed.