Relaxing Shear Stress Limit for the End Region of Prestressed Concrete Girders

This paper investigates the potential for relaxing the 0.18fc′ shear stress limit imposed by AASHTO load-and-resistance factor design (LRFD) in the end regions of prestressed concrete girders with relatively large bottom flanges, which often exceed this limit based on an analysis of experimental data. Extreme scenarios involving key characteristics of prestressed girders, such as total prestress loss, strut angle, strand pattern, skewed end block, and inclined web, are proposed to evaluate maximum shear stress. The shear evaluation method, which is based on the strut-and-tie method (STM), is applied to predict maximum shear stresses under these extreme conditions. An analysis of the shear capacity in the end regions of girders with large bottom flanges, such as Texas standard prestressed girders and decked slab beams, indicates that such girders commonly exceed the 0.18fc′ limit, with ratios reaching up to 0.22fc′ depending on their size. These findings suggest that the shear stress limit could potentially be relaxed, providing a rational basis for more economical design considerations.