This thesis, developed in collaboration with SINA S.p.A. of the ASTM Group, investigates the structural adequacy of prestressed Gerber beam bridges constructed during Italy’s 1970s highway infrastructure expansion. The research focuses on the critical shear assessment of girder beam end half-joints, which exhibit insufficient transverse reinforcement according to contemporary design standards. A comprehensive comparative analysis between 1970s design codes and current Italian technical standards (NTC2018, DM 578- Linee Guida Ponti) reveals significant discrepancies in shear reinforcement requirements, with conventional verification procedures indicating substantial structural deficiencies for many existing bridges. The study develops advanced nonlinear finite element methodologies using ANSYS software to accurately simulate the complex stress distribution patterns within these critical structural elements.