Capacity Evaluation of a Prestressed Concrete Adjacent Box Girder with Longitudinal Cracks in the Web

Abstract

In 2008, 77 prestressed concrete adjacent box girder (PCABG) bridges were selected and inspected to determine their typical defects and document their performance. Longitudinal cracking in the web of many beams was documented as the main defect. To evaluate the influence of longitudinal cracking on capacity of the PCABG, two adjacent box girders were compared that were made with the same procedure. One box girder (beam No. 1) had no defects, whereas the other (beam No. 2) had longitudinal cracks in the web. The results show that the longitudinal cracks in the web of beam No. 2 changed the trend of the expansion of the cracks by connecting the vertical cracks close to the longitudinal ones and shortening the range of the vertical cracks covered and the length of the plastic hinges. Furthermore, the longitudinal cracks made the curvature of beam No. 1 less than that of beam No. 2 and made the compression strain of each side different. However, the existence of longitudinal cracks had little effect on the cracking moment and the ultimate flexural bearing capacity. The residual prestressing forces indicated that an approximately 23% prestressed force was lost for both beams.