Purpose. The purpose of given work is the development of method for bearing capacity determination of metal spans with solid wall with upper-level traffic for the railway based on the results of static tests of given type of spans. Methodology. For the span that is being classificated the survey is being conducted and the deflection under the static load using simple measuring devises (deflectometers) are performed. Obtaining the deflection data is not complicated but gives the actual view of the span condition including hidden flaws (condition of bearing parts, corroded weakenings, that are very significant) Findings.. For the possibility of the given method of bearing capacity (class) determination for spans of given type application, first of all, from the numerous reports the selection was made of the main parameters of spans, results of static deflection measurements and load types. Based on the tests data the plot was drawn for the span experimental deflection dependence from the nominal span length. Originality. Based on the literature sources, this work is new in given direction and further such method is to be implemented for the common use by the development of the addition for the current standards [6]. Practical value. The analysis of obtained results shows that the application of given method on all the railways of Ukraine during the classification of metal spans will allow only by the recalculation to increase the actual bearing capacity of spans by 10..35 %.
In the article theoretical bases of the modified calculation method of circular outline tunnels are considered
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.
Purpose. To confirm the result of bridge span classification by using the computer modelling for truss span with upper-level traffic and polygonal lover belt and to determine minimal sufficient complexity of computational model that provides a possibility of adequate numerical calculation of given structure. Methodology. The result confirmation was executed by the comparison of stresses, that were yielded as a result of truss’ model loading with loads of predetermined class, with allowed stresses that were adopted for the determination of the afore-mentioned loading. The determination of optimal computational model was performed by the comparison of calculation results for models of different complexities. Findings. The results of the span modelling are similar enough to the results of it’s calculation, which confirms the accuracy of both methods and provides obvious idea about work of truss elements and critical places. The comparison of calculation results of different models showed that the using of shaft model with hard junctions and elements’ bending accounting is optimal. Originality. Computer modeling was used to confirm the results of span classification, which was conducted by the standard method. An optimal computational model was determined for trusses that are similar to given. Practical value. Results of analytical calculation were confirmed with demonstration of critical elements and obvious demonstration of results. The optimization of the model allows to lower calculation time and complexity of executing them for similar trusses.
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