DETERMINATION NATURAL VIBRATIONS OF THE CONTINUED PLACED ON CURVE FLYOVER IN OPERATION

Abstract

Purpose. The study of the dynamic behavior, the definition of shapes and natural frequencies of the bridge structure, which were designed and built at a time when the dynamic calculation of complex structures carried by simplifying the design schemes. Methodology. To obtain accurate dynamic characteristics of the structure under the action of wheeled vehicles on the bridge crossing, it was decided to use the calculation method of mathematical modeling of structures, namely finite element method. Simulation and calculation of this structure was carried out in an environment of « Lira." Drafted model meets all geometric and linear characteristics of the real structure, which is confirmed by the results obtained and the values obtained in the tests that were conducted BSRL of Dynamics bridges. Findings. On the basis of the calculations it follows that all forms of free oscillations of the overpass are mutually connected with each other and thus share the eigen modes of structures on vertical, horizontal and torsionalonly conditionally. Accepted scheme of the finite element model flyover solves problems related not only to the dynamic characteristics, but also to determine the actual values of internal forces ( normal , transverse moments) in any given structural member when subjected to a single fixed force or group of forces. Originality. As is known, the current trends of domestic and foreign bridge construction associated with the widespread introduction of new highstrength materials, the improvement of the design and technological forms and methods of calculation. Changes these factors in structures resulted in a reduction of rigidity , increased sensitivity to their dynamic effects. In this regard (as well as the intensity and magnitude of load) increased the role of dynamic calculations, studies the dynamic behavior of the bridge structure. Practical value. Based on the results of mathematical modeling ofatypical superstructure of the bridge, it can be argued that the use of the finite element method is an effective way to determine the dynamic characteristics. Also positive difference of this method from others is the ability to visualize the results, allowing you to identify the characteristic features in the building.