The Class Definition for Railroad Reinforced Concrete Bridge Span by Its Frequency (Period) of Characteristic Oscillations

Abstract

Purpose. The purpose of this study is to develop a methodology for determining the bearing capacity of reinforced concrete spans for the railway by the results of static or dynamic tests of the spans. Methodology. For the span that should be classificated, the survey is being conducted and the measurements of deflections and natural frequency are performed under passing vehicles, using simple measuring devices (flexometer, vibrograph). Received deflection and frequency data is not complicated but it gives a real picture of the given span condition taking into account hidden defects that is very essential. Findings. Based on the large number of tests for this type of spans, two beams for which there are results for both deflection and frequency are taken for the calculations. Calculations were performed with the given method (by frequency of natural oscillations and deflection) and with the general method [3]. The results indicate that the proposed method yields results that are significantly different from those obtained with the general method (up to 40%). This is the percentage that constitutes the safety factor of the span. Originality. Based on the literary sources, the work in this direction is novel and it’s proposed to implement this method for general use by developing updates for existing guidelines [3]. Practical value. Analysis of the received results indicates that the application of this method for all the railways of Ukraine will enable by the recalculation only to increase actual bearing capacity of spans by 30…40% while classification of reinforced concrete spans, this it will shift a significant number of spans from the unsatisfactory condition to satisfactory one and from satisfactory to the good one.