The main purpose of this study is to investigate, both experimentally and numerically, the retrofitted strength of concrete cylindrical shells reinforced with single layer under concetrated load. Although reinforced concrete shells are highly prone to be affected by various phenomena, such as earthquakes, impacts, winds, and explosions, the retrofitted strength of reinforced concrete shells has hardly been reported and evaluated. This paper treats the case of shell structure damage only within a local region. Three kinds of retrofits to the affected shells were adopted. Precut retrofit was firstly defined as the method for cutting the region adjacent to the affected boundary to be smoothed in order to avoid stress concentration. Next, filler retrofit was defined as the method for filling the region with shrinkage-compensating mortar after application of the precut retrofit. Lastly, sheeting retrofit was defined as the method for covering the surface of the region with carbon fiber sheets after filler retrofit. Each retrofitted region with and without steel reinforcement was investigated. An experimental study was conducted on small-scale models under a one-point concentrated load. Furthermore a numerical study was also conducted by material and geometrical nonlinear FEM analysis considering fluctuations of the shell thickness. The retrofitted strength of concrete shells reinforced with single layer under concetrated load was discussed based on the results of experiments and numerical analyses.
