Simplified evaluation of seismic behavior of beam-column joints in reinforced concrete frames

A simplified analytical model of joint behaviour is discussed and theoretical simulations are performed in order to fully understand the seismic performance and the failure modes of beam-column joints in reinforced concrete buildings. The rationale of the model is also to identify the strength hierarchy in terms of capacity for different failure modes (namely failure of the cracked joint, bond failure of the passing through bars, flexural/shear failures of beams or columns). The model focuses on both internal and external perimetric beam-column joints. In this way this model results in a tool for the designer of new joints to quantify the performance of new structures, but also as a tool for the designer of external strengthening of existing joints in order to quantify the benefits of the operations and pushing the initial failure to a more desirable failure mode. Further, some results of tests available in the scientific literature are reported, analysed and compared.