Bridges, Tunnels and other Transportation Structures
Full Session with Abstracts
Some steel structures, such as hydraulic navigation and marine structures, operate in harsh wet and corrosive environments and can suffer significant deterioration. The deterioration manifests itself in the form of corrosion, fatigue cracking, or a combination of both. While typically viewed as a nuisance, if left unrepaired, the deterioration can threaten the integrity of the structure. Repairing these cracks using conventional repair methods have proven to not only be time-consuming but also ineffective. Recent advances in the use of Carbon Fiber Reinforced Polymers (CFRPs) to retrofit structures have demonstrated its viability as a solution for increasing fatigue life of metal structures. However, the applications have been primarily focused on the aerospace and bridge industries and very few studies have been concerned with retrofitting metallic structures under wet and corrosive environments. Therefore, there is a clear need to evaluate the possibility of using CFRP to repair underwater metal structures. To this end, a new experimental setup was devised to allow for underwater testing of large-scale steel panels retrofitted with CFRP patches. The purpose of this experimental study was to provide a first-of-its-kind benchmark data by which the potential for using CFRP for underwater fatigue repair of metallic structures can be assessed. In this study, five large scale steel panels were tested, three of which repaired with CFRP patches, under different environmental conditions. The focus was to evaluate the effect of CFRP retrofit on crack growth rate. Since the application in this study pertained to water navigation structures used in rivers, the effect of fluvial sediments as well as salt were considered. The use of salt allowed for accelerated corrosion in the specimens to represent actual condition of deteriorated panels. Test results for dry and underwater specimens showed an increase in fatigue life with use of CFRP in comparison to bare specimens. The results also showed an increase in debonding susceptibility of the CFRP when the CFRP/adhesive system was subjected to corrosion, turbulence, and sediment particles.