Numerical modeling of shells repaired using FRP

Extensive research has been conducted on the use of fibre reinforced polymer (FRP) composites to strengthen concrete, masonry and timber structures as well as metallic beams. The failure strength, rather than considerations of stability has been the main concern in these studies. This paper presents a numerical modelling study of isotropic thin metallic cylindrical shells that have been repaired using orthotropic FRP to increase the resistance to elephant's foot buckling. This form of buckling occurs under high internal pressure accompanied by axial forces in the shell structure, and is commonly found in earthquake damaged tanks and silos. The strengthening effect is shown to be sensitive to the amount of the FRP: both too little and too much FRP lead to a lower strength than the optimal amount.