Calculation of forces and displacements of typical bridge span beams reinforced with ordinary and prestressed reinforcement

Introduction. Many bridge structures worldwide were designed in accordance with outdated standards and no longer meet the demands of modern transport loads. This creates a global safety issue, making the development of effective solutions for their strengthening a critically important task. Problem Statement. he vast majority of the global bridge infrastructure, particularly in developing countries, was constructed in the mid-20th century. The design of these structures was based on the normative loads of that time, which were significantly lower than current ones. Today, the increase in traffic intensity and the emergence of oversized and heavy-duty vehicles lead to bridge overloading. This causes premature physical wear of the structures, the appearance of cracks, a reduction in their load-bearing capacity, and, consequently, poses a safety threat to all road users. Materials and methods. The methodology of this study is based on a comprehensive approach that combines theoretical analysis, mathematical modeling, and numerical calculations. The purpose of using these selected methods is to substantiate the need for strengthening existing reinforced concrete bridge structures and to prove the effectiveness of external prestressed reinforcement compared to traditional solutions. The research is based on the Finite Element Method (FEM). This numerical method allows for approximating the behavior of a complex structure by dividing it into a set of simple elements (finite elements). This makes it possible to accurately determine the stress-strain state of the entire object. The calculations were performed using the licensed software package LIRA-SAPR, a modern tool for modeling, analyzing, and designing building structures.