Repair of strand-debonding damaged prestressed girder-deck system

The highway bridges near industrial facilities may experience strand-debonding damage due to the large volume of overloaded trucks. Under frequent overloads, the bond between strands and the surrounding concrete at critical section in bending deteriorates, which results in debonding over that section. Prestressed concrete (PC) bridge girders offer extra flex- ural strength compared with conventional reinforced concrete bridge, due to their embedded prestressing strands. The level of strength depends on the integrity of the concrete-strand bond in pretensioned concrete girders. Therefore, sufficient strand bond is necessary in PC girders to ensure the transfer of prestressing force and to guarantee the ability of strand to perfectly work on increasing stress once the girder is overloaded. This paper investigates an in-depth analysis on flexural behaviors of a girder-deck system experiencing a strand debonding damage repaired with various strengthening systems, based on finite element software ABAQUS. Two retrofitting techniques were proposed by the use of Carbon Fiber Reinforced Polymer (CFRP) or Steel Plate (SP), and a detailed finite element analysis (FEA) model was developed and verified against the relevant experimental data conducted by other researchers. It was demonstrated that the finite element model could be used to predict flexural behavior for debonding damaged prestressed girder-deck system with strengthening systems. Based on the verified FE model, 51 girder-deck systems were investigated with the consideration of following variables: 1) debonding level, 2) strengthening type, and 3) strengthening material amount. The parametric study was conducted to investigate the effects of above variables on flexural behaviors. It was found that different debonding lengths can significantly affect flexural performance. A longer debonding length for strands has a lower ultimate strength than a relatively shorter debonding length. However, the ductility increases with longer debonding length.