The inspection of effects of common arrangements of FRP sheets on improvement of seismic performance of concrete beam-column side joints

In reinforced concrete structures and especially those involving bending frame systems, beam-column joints have a key role in seismic energy dissipation. In past earthquakes, the vulnerability of these joints has been reported several times. Hence, in vulnerable structures, seismic performance improvement of these joints can help improve the overall structural performance. Seismically retrofitted joints using FRP has been widely under focus in recent years. Past researches have shown that the type of FRP sheets and their arrangements can influence the efficiency of this method of retrofitting.
In this research, five arrangements of FRP sheets on a side joint have been examined and the load–displacement chart and seismic demand values such as strength, ductility, energy absorption and primary stiffness as well as failure mechanisms are examined and finally the optimal arrangement is offered. The most optimal strengthening arrangement against all values of seismic demands is observed to be the crosswise arrangement which is the most effective to improve the seismic performance of non-strengthened joint in comparison with the other arrangements. All models are made in the ABAQUS software through the finite element method scheme and in all simulations cyclic loads are used.