Shear lag and shear deformation in box girders considering tendon transverse layout by improved beam element model

The transverse and vertical layouts of tendons within prestressed concrete (PC) box girders induce complex mechanical behaviors that necessitate precise evaluation for effective structural design. However, existing investigations often overlook the impact of tendon transverse layout. To address this gap, an improved beam element, designated as B12TS, is developed for shear deformation and shear lag analyses of PC box girders under prestressing effects. The element integrates the tendon transverse layout through non-uniform longitudinal displacements of the tendons modeled as a series of piecewise linear segments. The prestressing forces are converted into equivalent nodal forces acting on the elements. The element shape functions are derived from the homogeneous solutions to the relevant differential equations. Comparative analyses involving various beam element models, available experimental data, and three-dimensional (3D) finite element simulations demonstrate that the B12TS element model significantly enhances the accuracy and efficiency of predicting both deflections and stress distributions. Furthermore, the effects of prestressing on the flange and web tendons of typical PC box beams are examined to quantify the impacts of shear lag, shear deformation, and tendon transverse layout. The findings reveal that the transverse layout of the flange tendons remarkably influences both the magnitude and distribution shape of normal stresses, particularly near anchorage locations. Consequently, the B12TS element model proves to be a valuable analysis tool for designing prismatic and non-prismatic PC box girder bridges with various tendon layouts.