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16 Figure 3.1. Crack comparator. When asked about established criteria for deciding when those that used only 0.5-in. strand diameters, so there seems to repair cracks, 16 of the 36 who responded said they had no to be no bias towards a preferred strand diameter. established criteria. The rest of the respondents repaired cracks Of those who responded, 72% believe strand distribution based on the size of the crack. Many used the PCI Manual for contributes to end zone cracking, and 50% believe it is due to the Evaluation and Repair of Precast, Prestressed Concrete Bridge detensioning. A few others think that strand size, lifting method Products (11) as a guideline for repair procedure. Repair is done insert locations, and concrete strength also contribute. Other by either painting a substance over the cracks or by injecting theories given were the uneven support of the beam after deten- a substance into the crack itself. Large cracks are injected and sioning, eccentricity of prestressing strand groups, changes in small cracks are just coated. Almost all respondents use a form temperature, restraint of forms during curing, form geometry, of epoxy to seal or inject the cracks. limitations of debonding, and the presence of draped strands. Of the 36 who experienced end zone cracking, 58% believed that their repair methods do not restore the tensile capacity 3.2 Structural Investigation and of the member and 20% believe it only partially restores the Full-Scale Girder Testing tensile capacity. Thirty-two of the 36, 89%, do not believe it is even necessary to restore the tensile strength of the girder. 3.2.1 Introduction In regard to rejecting a girder due to end zone cracking, The objectives of the full-scale girder testing were to inves- most respondents said they deal with the beams on a case-by- tigate (1) if end zone cracking negatively affects the flexural case basis. Rejection would be based on the width and length and shear capacities of prestressed girders, and (2) if variations of the crack along with its placement on the beam, the num- of the end zone reinforcement details have significant effect ber of cracks and their proximity to one another. Most stated on the number, width, and pattern of end zone cracks. The that rejection is rare or they have never seen a beam rejected test plan had eight full-scale girders fabricated in four states for these reasons. The literature review showed that it is a with different end zone reinforcement details. This was done common belief among design engineers, precast producers, through direct contact between the research team and precast and contractors that repaired girders can be used as long as the concrete girder producers in four states (Tennessee, Florida, end zone cracks are sealed and the cracked part of the girder Virginia, and Washington). Each precast producer agreed to is embedded in the diaphragm. Some DOT agencies such as fabricate two specimens as part of an actual bridge girder Washington State DOT believe that these cracks will close up project. This was done through the following steps: to some extent due to the weight of the girder, deck slab, and barriers. This is because usually the direction of the end zone 1. Each precast concrete girder company picked an actual cracks is normal to the direction of shear cracks, which means bridge girder project where the precast girders would be that the end zone cracks will be subject to diagonal compres- manufactured in its yard. The criteria for a good candi- sive stresses that help to close them up. date project were: (a) the girders should be packed with Of the 36 who experienced end zone cracking, 31 used a large number of strands in order to produce end zone flame cutting of individual strands as their only method or cracking, and (b) the type of girder should be different from one of their methods for strand release. Eight used a hydraulic those picked by other precast producers in order to have release (jack down) of all strands in one step, or of individual four different types of girders tested in the project. strands. Most respondents used a mix of 0.6-in. and 0.5-in. 2. The precast concrete girder companies provided the re- diameter strands in their girders. There was an equal distri- search team with details of reinforcement of the actual bution of those that used only 0.6-in. strand diameters and girders and their time plan to fabricate these girders.