An alternative procedure for the performance assessment of FRP-retrofitted RC buildings using lumped plasticity

A reinforced concrete (RC) building designed prior to current codes for seismic design and guidelines for detailing RC beam-column joints needs to be evaluated against the new seismic requirements. Members found to be deficient need to be monitored and subsequently retrofitted. One solution for retrofitting a deficient RC joint so as to avoid brittle joint core failure in an earthquake is to increase its ductility by shifting potential plastic hinges away from the joint. Fibre reinforced polymers (FRPs) are increasingly used to perform such retrofitting. Non-linear static (pushover) analysis can be a fast and relatively accurate method for evaluating the overall seismic performance of a regularly shaped building. It can be performed on commonly available and easy-to-use lumped-plasticity frame analysis (LPFA) computer programs, such as SAP2000. However, such programs cannot directly determine the amount of retrofitting required for each joint and its enhancing effects, a task that only a spread-plasticity frame analysis (SPFA) program can do. Therefore, time-consuming finiteelement analyses (FEA) of the joints need to be performed first before transferring the properties over to the LPFA program for the pushover analysis. This paper will use a LPFA program to indirectly approximate the amount retrofitting required thus replacing the FEA step. The successful results show that this new approach can be easier and more time-efficient than current methods.