• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5A
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• pp.841-848
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• 2006

There is a complex variation of stress in PSC anchorage zones and box girder diaphragms because of large concentrated load by prestress. According to the AASHTO LFRD design code, three-dimensional effects due to concentrated jacking loads shall be investigated using three-dimensional analysis procedures or may be approximated by considering separate submodels for two or more planes. In this case, the interaction of the submodels should be considered, and the model loads and results should be consistent. However, box girder diaphragms are 3-dimensional disturbed region which requires a fully three-dimensional model, and two-dimensional models are not satisfactory to model the flow of forces in diaphragms. In this study, the strengths of the prestressed box girder diaphragms are predicted using the 3-dimensional grid strut-tie model approach, which were tested to failure in University of Texas. According to the analysis results, the 3-dimensional strut-tie model approach can be possibly applied to the analysis and design of PSC box girder anchorage zones as a reasonable computer-aided approach with satisfied accuracy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.53-60
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• 2024

Prestressed concrete (PSC) bridges are vulnerable to corrosion and fracture of tendons, and in particular, structures using the internal post-tensioned with grouted system have difficulties in maintenance due to limitations of inspection. In this study, the actual behavior of PSC I girder bridge was analyzed according to tendon damage. The target PSC I girder bridge, an decommissioned highway bridge of upper and lower bridges, had the service period of 33 years and 20 years, respectively. Deflection and concrete strain were measured according to the location of damaged tendon and loading method. Regardless of the age of the bridge, its structural performance decreased when the damaged tendon was closer to the center of the girder. The change in behavior increased as the truck load approached to the girder where the tendon cut. If the load was applied to the adjacent girder where the tendon was cut, the structural performance was likely to be maintained due to the influence of the entire structural system. The change in deflection was difficult to observe visually, while the concrete strain exceeded the cracking strain. Therefore, it is recommended that future monitoring and inspection of PSC I girder bridges should focus on concrete strain or cracking.