Evaluation of crack control methods for end zone cracking in prestressed concrete bridge girders

Deep prestressed concrete bulb-tee girders exhibit cracking near the ends during prestress release. These cracks discourage engineers from using deep sections or may result in the rejection of the girders. The durability of the members is of concern, particularly if chloride ions reach strands through cracks. The effectiveness of various crack control methods used by the industry has not been well quantified or compared. This paper describes an evaluation of the effectiveness of existing and proposed crack control methods. The girder ends were analyzed using nonlinear finite element analysis verified by test data. Among the most effective crack control methods were debonding the strands at the ends, locating the lift loops at a distance equal to the girder depth from each end, and detensioning the strands beginning with the innermost ones.