Based on the small-deflection theory, simply supported prestressed concrete girder-bridges are shear deformable members because concrete is treated as a shear deformable material. However, when the slenderness of prestressed concrete girder-bridges is significant and elastic shear modulus assumes higher values (high-strength concrete), the shear effect can reasonably be neglected even in presence of finite-stress and shear values. This is generally sufficient for practical purposes in structural engineering. In this contribution, two high-fidelity finite-element models assuming geometric nonlinearities have mainly been implemented to analyze such an issue. According to the comparison with static tests on a concrete beam subjected to different values of post–tensioning, reported in literature, the shear deformation should strongly be considered for a better accuracy in most simulations of structural modeling, and identifying the existing prestressing force through a nondestructive method based on small-deflection measurements.