Numerical assessment of concentrated plasticity models of ductile RC frames in non-linear dynamic analyses

The study evaluates concentrated plasticity formulations used to model ductile reinforced concrete frames in non-linear dynamic analyses. Four frames with increasing number of stories (2, 4, 8 and 12) are modelled in OpenSees and assessed under a set of spectrum-compatible input ground motions, investigating the effect of modelling decisions on the length of the plastic hinge region and the flexural stiffness of the cracked concrete section. The results highlight that modelling choices mainly affect the estimates of inter-story drift ratio and maximum base moment, while effects on floor acceleration and maximum base shear are low; the effective flexural stiffness of cracked concrete must account for the axial load in the structural member.