Solid finite-element modeling of prestressed beams. Part I: Concrete girder-bridge with a straight tendon

Prestressed concrete girder-bridges are shear deformable beams because concrete is a shear deformable material. Their shear deformation in terms of second-order effects is usually neglected since the slenderness of concrete girder-bridges is generally significant. This is commonly the practice in applications of bridge engineering. In this article, a high-fidelity solid finite-element model using the Strand7 program, and assuming geometric nonlinearities, was accomplished to study such an issue. Comparisons with static tests executed on a simply supported concrete specimen composed of straight tendon, significant slenderness ratio, high-strength concrete, and subjected to different post–tensioning, reported in literature, were elaborated. Subsequently, with the aim to identify the effective post–tensioning forces, the solid finite-element model was adopted to compute the parameters of the magnification factor formula of the second-order shear effects. Accordingly, the shear deformation in prestressed concrete girder-bridges should highly be considered for obtaining better accuracies, in terms of results, in most evaluation techniques. Yet, this work was a preparatory contribution with the goal to simulate the “static deflected shape” method for predicting prestressing force in a multi-span concrete girder-bridge based on small-deflection measurements. Moreover, in the second article of this work, a concrete specimen with parabolic tendon, and subjected to time-dependent post–tensioning losses, was instead taken into consideration.