JUSTIFICATION OF CAPITAL REPAIR OF A HIGHWAY BRIDGE WHEN CHANGING THE LOAD

Purpose. The purpose of the scientific article is to substantiate the implementation of capital repairs of a road bridge that has been significantly damaged as a result of hostilities. The achievement of this goal is based on numerical analysis of the model using the finite element method, taking into account recommendations for reinforcing bridge elements. Methodology. Loads and impacts gathered during numerical analysis ensure the verification of bridge structures and elements for strength, stability, and durability according to the first group of limit states criteria, as well as stiffness and crack resistance according to the second group of limit states criteria. Temporary loads and impacts for structures calculating for all groups of limit states are taken with reliability factors for loads γf and dynamics factors (1+µ). The structure utilizes standard I-section beams for the superstructure with lengths of 22.16 m and 32.96 m, designed according to the working drawings and calculations developed by "International Design Institute" LLC and modeled in the professional structural analysis software Lira-CAD. Findings. The calculation of the beams was performed in two stages, reflecting their work: Stage 1 – Concreting the slab, the slab is not included in the structural analysis; Stage 2 – The slab is included in the span work, concreting of sidewalks without inclusion in the structural analysis, laying of asphalt concrete pavement, barrier railing, guardrails and expansion joints. The structure of the temperature-continuous monolithic slab, calculated using the Lira-CAD structural analysis software, has been reinforced considering the entire range of loads. Originality. The originality of the study lies in the scientific substantiation of carrying out major repairs on the bridge, which provides the possibility of the passage of temporary vertical loads according to H-30 and NK-80 schemes and pedestrian load on the sidewalks. Practical value. The practical value lies in the justification of the works on the restoration of the bridge design characteristics. Moreover, the calculations of the loads and impacts provide verification of the structures and elements of the bridge as well as the sequence of work operations during construction.