Reinforcing the Beam-Column Joint

Reinforcing the Beam-Column Joint

 Diagonal cracking & crushing of concrete in joint region should be prevented to ensure good earthquake performance of RC frame buildings. Using large column

sizes is the most effective way of achieving this. In addition, closely spaced closed-loop steel ties are required around column bars (Figure 3) to hold together concrete in joint region and to resist shear forces. Intermediate column bars also are effective in confining the joint concrete and resisting horizontal shear forces.

Providing closed-loop ties in the joint requires some extra effort. Indian Standard IS:13920-1993
recommends continuing the transverse loops around the column bars through the joint region. In practice, this is achieved by preparing the cage of the reinforcement (both longitudinal bars and stirrups) of all beams at a floor level to be prepared on top of the beam formwork of that level and lowered into the cage (Figures 4a and 4b). However, this may not always be possible particularly when the beams are long and the entire reinforcement cage becomes heavy.