Analysis of the Application of Analytical and Numerical Methods for the Dimensioning of Pin Connections of Folding Bridges

This paper presents a static-strength analysis of the construction of folding bridges, addressing in particular the dimensioning of pin connections. These connections are elements that transfer the axial forces between the chords of truss girders of connected span sections. First, the various components of folding bridges and the materials from which they are made are characterised. The characteristics of pin connections in modern folding bridge structures are discussed, including their influence on the static scheme of the entire structure. The parameters of such pin connections are presented in terms of both the strength of such a connection and cooperation of its components. The main part of this article is a detailed design analysis of the pin connection of the new MSC 23-150 “Cis” folding bridge structure, the concept of which was developed at the Faculty of Civil Engineering and Geodesy of the Military University of Technology. The calculations were carried out both analytically and with a spatial numerical model, which allowed us to determine the stresses on the connection components in the critical sections and propose the final shape of the connector. This article presents the effect of combining known methods of dimensioning pin connections and a method related to determining actual stress values by taking into account the so-called stress concentration factor in analytical calculations. Taking into account the real area of impact of the pin on the bridge pin joint element affects the stress concentration, which can cause an increase in stress in selected cases by up to 300%. Original results are presented on the relationship between individual stress values in specific cross-sections of the connection and the values of assembly clearances in prefabricated bridge structures, as well as their mutual relationships for specific values of assembly clearances. The above information is important when developing and operating bridges made of portable truss-type bridge structures. Knowledge of the phenomenon of stress concentration reduction when limiting assembly clearance allows for the safe and effective use and construction of this type of bridge structure.