Seismic performance of reinforced concrete column with repeated damage and repairs by resin injection

Abstract

In regions prone to earthquakes, it is possible that reinforced concrete (RC) columns may experience multiple cycles of earthquake-induced damage and subsequent repair. Moreover, in practical situations, RC columns subjected to axial forces are often repaired without the use of temporary support systems to bear the weight of the superstructure, and frequently while residual drift remains. This study conducted cyclic loading tests and resin injection repair tests on RC columns twice to evaluate their seismic performance when repeatedly damaged and subsequently repaired. The resin injection repairs were performed with axial forces applied to the columns, considering the presence or absence of residual drift at the time of repair as an experimental factor. The results showed that although the resin injection repairs restored the maximum lateral load capacity of the columns to their original levels, the stiffness was not fully recovered. A significant finding was a 10 % to 20 % reduction in yield stiffness from the first to the second repair. Furthermore, incremental dynamic analyses were performed to investigate the effects of changes in lateral load capacity after resin injection repairs. The numerical results indicate that seismic response displacement increased significantly for small to moderate seismic motions due to resin injection repairs, while the response displacement at the ultimate level of the columns remained largely unaffected. Moreover, it was observed that the number of resin injection repairs and any asymmetry in seismic performance post-repair had a less substantial impact on the seismic response than the differences observed between as-built and repaired columns.