Studies on nonlinear behavior of retrofitted reinforced concrete beam column joints after experiencing severe damage from earthquake load simulation

For an earthquake resistant structure, reinforced concrete building must have certain performance level under certain level of earthquakes such as when it is subjected to a strong level earthquake, it may experience severe damages, but without partial or full collapse, thus some reparations could be done to recover the functions of those damaged structures. However, repairing methods were usually done to slightly-damaged structures, while for severely-damaged structures, more studies are still needed to optimize the effectivity of the repair. Therefore, the objective of this study is to evaluate the performance of a structure that is retrofitted using high strength concrete after experiencing severe damage from an earthquake. Reinforced concrete beam column joints - that are used as specimens for this study - were initially subjected to cyclic loading up to 5% drift. The specimens’ beams are then repaired by replacing the damaged concrete with the new, stronger concrete without replacing the existing reinforcement bars. The retrofitted specimens are then subjected to the same cyclic loading and their nonlinear behaviors are compared to the behavior of their initial condition. The experimental results show that there are mostly reductions in lateral strengths, although there is an increase of strength in one specimen, while there are also reductions in energy dissipated