Assessment of the Technical Condition of the Pedestrian Bridge Damaged as a Result of Military Actions

The article presents the results of the technicalcondition assessment of the pedestrian bridge overthe Desna River in Chernihiv, which was damaged asa result of military actions. The relevance of the workis due to the need for a comprehensive approachto assessing the technical condition of the bridge'sstructures and elements that have been damageddue to the impact of various munitions, and to justifydecisions regarding its further safe operation. Thestudy utilized visual and instrumental inspections, aswell as dynamic testing of the bridge's spans. Duringthe inspection, characteristic structures and elementsthat were damaged during military actions wereidentified. Based on a qualitative and quantitativeassessment of defects and damages to structuralelements caused by military actions, consideringthe worst indicators, the bridge's condition wasdetermined as state 5 – inoperative. Measurementsof the actual strength of the concrete of reinforcedconcrete elements were performed non-destructivelyusing the ONYX 2.5 device. The survey found: thestrength of the concrete of the beams of the spansis within 44.4–47.4 MPa, which corresponds to theconcrete class C25/30–C30/35; the strength of theconcrete of the supports is within 40.1–46.8 MPa,which corresponds to the concrete class C25/30–C30/35. The strength of the concrete in the structuralelements of the bridge has not decreased over timeand meets the design requirements. Dynamic testingof the bridge included determining the frequencyspectrum of natural oscillations of a three-spanstatically indeterminate metal continuous single-boxgirder on four supports as a monolithic structure.However, the damages to the bridge's span structureresulting from military actions, established accordingto requirements 1 to 3, do not allow the use ofload equivalents from previous tests in 1990 andprevent their full comparison 4. The comparisonof oscillation frequencies when exciting the spanstructure with vertical thrusts with the frequencies ofvertical oscillations obtained during the tests in 1990showed a coincidence of their values with an averagedeviation of 4.1%. The damages that the structuralelements of the bridge received as a result of militaryactions did not lead to significant changes in thedynamic characteristics of the metal span structure.