Shear behavior of large-scale post-tensioned girders with small shear span-depth ratio

This study investigated the shear deformation of large-scale reinforced I-shaped girders and post-tensioned prestressed concrete (PSC) girders with a small shear span-depth ratio of 2.5. The test variables were the compressive strength of the concrete, the stirrup ratio, and the prestressing force. This large-scale experimental study enabled the investigation of diagonal cracking behavior, namely crack zones, patterns, principal strain direction, and crack width, as well as ultimate shear capacity. This extensive information can be used to establish the formation of compressive struts and force-resisting mechanisms in shear analysis. From the experimental results, it was shown that the ultimate shear capacity of concrete girders increased with an increase in the concrete compressive strength, the stirrup ratio, and the prestressing force. The effect of concrete strength in the girders with stirrups and prestressing force, however, was not much as in those without stirrup and prestressing force. It has been also shown that the stirrup is highly effective for controlling diagonal crack width, whereas the prestressing force is only effective at delaying cracking load. With the comparison of the crack zones of the test girders, it is found that the stirrup ratio is the dominant factor in the arch action of a beam member with a short shear span-depth ratio. The results of this study are referenced and used in the accompanying paper, which focuses on verification of realistic analytical models showing shear deformation of PSC girders.