Shear Behavior of Post-Tensioned Girders

An experimental program was performed to evaluate the strength of post-tensioned girders loaded in shear and, more specifically, to investigate how a post-tensioning duct located in the thin web of a bulb-tee bridge girder impacts the shear-transfer mechanism and ultimate shear strength of the member. Considering the limited number of tests on full-scale post-tensioned girders reported in the literature, the experimental program included 10 shear tests on post-tensioned bulb-tee girder specimens with a total height of 70 in. (1778 mm). An additional test was performed on a control specimen that was not post-tensioned and therefore did not contain a duct. A primary interest of the testing program was the effect of the duct material (steel or plastic) on the behavior of the specimens. The test results indicated that essentially no differences existed between the shear strength of the girders containing grouted steel ducts and those containing grouted plastic ducts. Keywords: bridge girder; duct; grout; panel; post-tensioning; prestressed; shear strength; tendon; web.