Effect of the Stiffness of RC Beam Column Connection on the Stiffness of Building

A beam-column joint is a very critical zone in reinforced concrete framed structure. In RC structures, failure in a beam often occurs at the beam-column joint. Sudden change in geometry and complexity of stress distribution at joint are the reasons for their critical behaviour. Stirrup spacing on beam-column connectios should be smaller in order allow for safety in carrying the stress.

Although monolithic beam-column connections are commonly treated as fully rigid, experimental results have already shown that there are relative rotations in these connections.

The existence of a lower stiffness in the partially retrained beam-column connection causes a redistribution of internal forces in the structurei resulting in higher values for global stability parameters(second-order effect), for positive bending moments in the span of beams and for longitudinal reinforcement area of the columns.

The semi rigid joint between beam and column provides a lower moment at the end of the beam when it is compared with fully rigid joint. This lower design moment can reduce the required section modulus of the beam and subsequently a potential cost savings may achieve.