Effect of Tendon Profile Layout on Flexural Strength of Unbonded Post-Tensioned Prestressed Concrete Bridge I-Girder

The main objective of this research is to evaluate the optimal design of the tendon profile layout and to examine the effect of the tendon profile layout on the flexural strength of unbonded, post-tensioned prestressed concrete bridge I-girders. In this study, the experimental investigation involved casting and testing ten unbonded, post-tensioned bridge girders under four-point loads. The main variable studied was the tendon profile layout. The experimental results showed that the flexural behavior of the tested specimens is divided into three stages, including the elastic stage, elastic–plastic stage, and plastic stage, and all specimens exhibited flexural failure. It can be concluded that for each tendon profile layout (trapezoidal, parabolic, harped), the tendon profile with eccentricity at the end of the beam (ee) = 0 had the maximum ultimate load capacity. It also can be concluded that specimen GF-2 HA (harped tendon profile with ee = 0 mm) had the maximum ultimate load capacity among all of the specimens. These enhancements in specimen stiffness, ultimate load capacities, and deflections are due to an increase in resisting capacity, a reduction in stresses, especially at the supports, a decrease in deflection, and an increase in the resisting bending moment, which lead to a reduction in the production cost of the girder.