Enhancement Of Service Life Of Prestressed Concrete Bridge Girders Using Frp Composites

Download or read book Enhancement of Service Life of Prestressed Concrete Bridge Girders Using FRP Composites written by Muhammad Shafqat Ali and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This research aims at enhancing the service life of the prestressed concrete bridge girders, using fiber-reinforced polymer (FRP) composite shell on the lower flange to impede the ingress of deleterious elements into the concrete. The FRP shell would help to retard the resulting deterioration reactions and achieve more durable bridges for a considerably increased service life. The behavior of prestressed concrete bridge girders with FRP shells on the tension flange was investigated experimentally.The flexural characteristics of FRP shell and concrete interface along with the effect of the steel reinforcement ratio were studied experimentally. This FRP shell was bonded around the lower part of the concrete beams, constructed with four different reinforcement ratios. The beam specimens with the FRP shell showed a significant enhancement in their strength, stiffness and energy absorption capacities, as compared with the associated control beams. The flexural behavior of cast-in-place prestressed concrete beams with FRP shell was studied to examine the contribution of the bonded FRP shell to the strength, stiffness, ductility and energy absorption capacity of prestressed concrete beam specimens, for five different levels of prestressing. The initial cracking, yield and ultimate strengths of the beam specimens with FRP shell were significantly higher than those of the associated control beam specimens. The FRP shell and the prestressing force enhanced the strength and stiffness of the beams. The long-term durability of the FRP shell to act as a barrier against ingress of aggressive elements, such as moisture and chlorides into the proposed FRP shell-concrete system, was examined experimentally in a preliminary manner. Detailed tests on concrete specimens reinforced externally with FRP shells subjected to accelerated moisture and salt solution at control temperatures were performed. In addition, scanning electron microscopy (SEM) was used to determine the effects caused by aging, with time, temperature and chloride injection pressure. The FRP shell, acting as a barrier, showed a significant resistance against chloride ingress by significantly slowing down the chlorides ingress rate and the total amount of chlorides. For a prestressed concrete girder with an FRP shell, the accumulated time for chloride penetration and reaching the level of prestressing steel strands was predicted to be more than 135 years. These results suggest that the FRP shell is quite effective in improving the durability characteristics of prestressed concrete girders and can significantly extend their service life. " --