NUMERICAL AND MODAL ANALYSIS OF THE RAILWAY BRIDGE PIER

Purpose. The purpose of the scientific research is to conduct numerical and modal analyses of the railway bridge pier with a variation of load combinations and to determine the strength parameters and dynamic characteristics (shape and frequency of natural vibrations). Methodology. Pile foundations are the most economical and effective for bridge construction. In this case, the pile foundation of the overpass pier is constructed on bored piles. To reproduce the features of the pier’s pile foundation, a spatial FE-model was used, which most accurately reflects its interaction with the surrounding massif. Findings. An analysis of the results of the stress-strain state of the overpass pier foundation was performed, taking into account the train load, which made it possible to obtain a conclusion about the high bearing capacity of all parts of the “pile – pile cap” system for all considered types of combinations with a safety margin of 8 and 7 times, respectively, which indicates normal operation in the future provided an unchanged state of engineering and geological conditions and loads. The connection point of the piles and the pile cap, made of concrete class C25/30, fully withstands all types of loads presented in the combinations. A modal analysis of the foundations of the overpass pier models was performed and the frequencies and shapes of the foundation were obtained, which are equal to 4.2 Hz (main tone) … 17.4 Hz, and from comparing these frequencies with the liquefaction frequencies of wet sands (30 … 50 Hz) it is clear that the support's own vibrations cannot cause vibration liquefaction. Originality. The originality of the study lies in obtaining the values of the stresses of the overpass pier in the static formulation, as well as the dynamic characteristics (shape and frequency of natural vibrations) in the dynamic formulation. Practical value. The practical value lies in the substantiated assessment of the values of the pier’s vibration frequencies, which is based on the results of modal analysis and indicates the absence of sand liquefaction.