Inspection Techniques for a Damaged Prestressed Concrete Girder Bridge: A Case Study

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Title: Inspection Techniques for a Damaged Prestressed Concrete Girder Bridge: A Case Study

Author(s): Y.J. Kim, R.G. Wight, and M.F. Green

Publication: Special Publication

Volume: 277

Issue:

Appears on pages(s): 129-142

Keywords: damage, deterioration, double-tee beam, inspection, over load, prestressed concrete

Date: 3/1/2011

Abstract:
This paper presents on-site inspection techniques to examine a damaged prestressed concrete girder bridge. The bridge is 18.3 m [60 ft.] and consists of double-tee beams (DT3000 x 700 ) with a 50 mm [2 in.] topping concrete. To simulate the effect of deterioration for the girder, the leg member is intentionally damaged by cutting 2 prestressing strands. A load test is conducted to evaluate the flexural behavior of the bridge before and after the damage. A site inspection is conducted after 10 months of the load test. The inspection techniques used for this study includes the visual inspection, pull-off test, ultrasonic test, rebound hammer test, core test, and surveying. The bridge exhibits significant cracks and spalling of the concrete in the deck and the legs. Corrosion of the reinforcing steels is observed. The pull-off test shows that the bond strength between the flange of the girder and the topping concrete is adequate. The ultrasonic test exhibits some internal defects of the leg member, including an increased transmission time of the ultrasound. The in-situ concrete strength measured is reasonably close to the specified 28 day concrete strength, based on the rebound hammer test and the core test, with an average error of 2.1%. Permanent downward deflections are not observed, whereas a maximum camber of approximately 35 mm [1.4 in.] is measured by surveying. The inspection techniques reported in this study are reliable and recommended to examine concrete bridge elements.