Repair of Damaged Prestressed Concrete Girders with FRP and FRCM Composites

Abstract

Traditional methods used to repair prestressed concrete (PC) girders subjected to impact damage due to overheight vehicles include strand splicing and external posttensioning. These methods have proven to be partially satisfactory in restoring the damaged girder’s ultimate strength. The use of composite materials in the strengthening, rehabilitation, and repair industry has been gaining popularity due to their excellent material behavior and ease of application. Composites such as fiber-reinforced polymer (FRP) and fabric-reinforced cementitious matrix (FRCM) systems are presently available alternatives for restoring the integrity of a damaged girder that eliminate the need for girder replacement. The use of externally bonded carbon FRP (CFRP) materials for the repair of damaged bridge components has been successfully deployed and has been shown to reduce repair costs and traffic closure time. FRCM composites represent an alternative material to FRP for structural retrofit/rehabilitation. However, the use of FRCMs is rather new and technical literature is limited in the United States and does not include design provisions for the repair of PC structures. The objective of this study is to evaluate both experimentally and analytically the effectiveness of FRP and FRCM as repair systems to impact-damaged precast PC girders. The specimens consisted of three PC girders retrieved from a bridge after 55 years of service. One specimen was load tested undamaged and used as a benchmark. The other two were damaged (four cut strands) and repaired with FRP and FRCM prior to being load tested. A cross-sectional analysis was performed to predict strength and behavior of all specimens using provisions of current design specifications and guides. Theoretical values were compared to experimental values and the effectiveness of the strengthening methods and respective design approaches were evaluated.