Abstract:  A 26 meters span post tension concrete box girder meets the design and code requirements on concrete strength, girder height, cross section dimensions, tension stresses and elongation. But the convex rate of the as-built girder was fairly lower than the design value. The asbuilt concrete box girder was loaded tested, independent analyzed and consulted by experts. Factors affecting the rate of the convex were able to be obtained. Finally, bridge safety concerns due to the lower convex rate of this post tensioned concrete box girder were eliminated.

Key words: Concrete Box Girder, Convex Rate, Error Range, Analysis of Factors