Purpose. The purpose of the study was to determine the stress-strain state and operating characteristics of the existing steel-reinforced-concrete span structure under the railway after long-term operation under static and dynamic loads. Methodology. To achieve the goal, full-scale surveys of the existing bridge crossing were carried out, more attention was focused on the steel-reinforced concrete span structure, the conditions and features of its operation were determined, and static and dynamic tests were conducted. During the tests, the general deformations of the span structures (vertical and horizontal deflections) and the stress state in the elements of the structures under different load schemes were measured. During dynamic tests, registration of static and dynamic component deflections and stress changes in structural elements during the passage of rolling stock along the span structure was carried out. The interaction of the span structure with the rolling stock, the influence of uneven approaches to the bridge on the excitation of the rolling stock was investigated. Findings. The values of stresses in the elements of the steel-reinforced-concrete span structure were obtained when the test load was installed in the position at which the greatest stresses and deformations should occur in the test elements, the frequencies of natural and forced oscillations of the span structure were measured, the dynamic coefficient, the dynamic deflections of the main beams were determined, the values decrements of oscillations of the frequency of natural and forced oscillations. The dynamic interaction of the rolling stock with the steel-reinforced concrete span structure was studied. Analytical assumptions in the design of steel-reinforced-concrete span structures of bridges have been confirmed. Originality In the work, a study of the stress-deformed state of the steel-reinforced concrete span structure of the railway bridge after long-term operation, the simultaneous operation of the span structure with rolling stock was carried out. Practical value. The operating conditions of the steel-reinforced-concrete span structure of the railway bridge, static and dynamic characteristics of its operation, the interaction of the rolling stock with the span structure, the influence of the unevenness of the approach track to the bridge on the dynamic interaction of the span structure and the rolling stock are determined. Practically confirmed analytical calculations of deformation and dynamic characteristics of steel-reinforced-concrete span structures of bridges, the joint operation of steel beam and reinforced concrete slab is ensured to a sufficient extent and corresponds to theoretical assumptions.
Purpose. The authors aim to determine the features of the operation of a steel-reinforced concrete span structure with beams reinforced with an I-beam, with their pre-stressing using the bending of a steel I-beam. Methodology. To manufacture a steel-reinforced concrete span structure, it was proposed to reinforce an I-beam with a camber, which is then leveled with the help of applied external loads. For practical convenience, the vertical external forces are replaced by horizontal forces that keep the metal I-beam in a deformed state and in this state it is concreted. After the concrete strength development, the external forces are removed and the metal I-beam creates the pre-stressing of the concrete. Findings. When determining stresses, checking calculations by analytical method and the method of modeling with the help of the ANSYS program were used. The stress diagrams along the lower and upper fibers of a metal I-beam and stresses in concrete in the upper and lower zones of the beam were constructed. The analysis of the results showed that the pre-bending of a metal beam can be used to create a pre-stressing, which improves the performance of steel-reinforced concrete span structures, increases their rigidity and allows using of such a structure to increase the balks of railway and highway bridges. Originality. In the paper, a study of the stress-strain state of steel-reinforced concrete beams of the railway span structure was carried out, taking into account the pre-stressing of the concrete. A method of manufacturing a steel-reinforced concrete beams is proposed, which provides pre-stressing of the reinforced concrete due to the bending of a steel I-beam. Practical value. As a result of the calculations, it was found that the structure, when manufactured by the specified method, has greater rigidity compared to reinforced concrete or metal beams. The height of the beam can be lower compared to reinforced concrete or metal span structures. These circumstances are essential for railway bridges, especially for high-speed traffic ones.
Purpose. The purpose of this work is to analyze the use of the property of the floating railway bridge NZM-56 for the technical cover of important transport facilities and the rapid restoration of road traffic through water obstacles in the territories of Ukraine affected by the hostilities, taking into account the challenges of the military today. Methodology. Studying the experience of guiding and operating automobile pontoon crossings from the property of the floating railway bridge (NZM-56) by units of the State Special Service of Transport across the Desna River in the Chernihiv region. Findings. The result of this work is collected data on the advantages and problematic issues that arose during the construction and operation of floating bridges, development of directions for further research to improve technical and operational characteristics. The use of available material resources, namely the property of the floating railway bridge (NZM- 56), for the construction of bridge crossings with floating bridges on the short bypass of the bridges destroyed as a result of the hostilities made it possible to quickly restore the movement of road transport on the roads of state importance. The identified weaknesses in the operation of floating bridges are the wooden bridge deck, which cannot withstand the intense wheel load and the small distance between the floating supports (pontoons) along the facade, which requires continuous maintenance of the crossing. Development of directions for further research to improve technical and operational characteristics. It is proposed to consider the possibility of using steel-reinforced-concrete span structures with a high percentage of factory production to cover the spans of floating bridges. Originality. The scientific interest lies in the fact that for the quick and high-quality restoration of traffic through wide and deep water obstacles, the available material resource (NZM-56) was used to guide road crossings, which significantly improved the transport logistics of the regions of Ukraine affected by the hostilities. Practical value. Based on the learned experience of floating (pontoon) bridges, it is possible to conclude that floating bridges are an effective way of providing transport logistics, have low advantages, therefore the use of these structures can ensure effective restoration of traffic.
Purpose. The issue of resuming automobile traffic is an important task for the resumption of logistical state and local movements. The purpose of the work is to study and implement the experience of restoring transport infrastructure and construction of fortifications, its distribution, and the wide implementation of lessons learned in the training process of units of the State Special Service of Transport and other bridge construction specialists. The experience of using reserve beams under railway load for a road bridge is shown on the example of the restoration of automobile traffic across the Irpin River for passenger cars without load capacity restrictions. An example of restoration of man-made structures on the detour next to the bridge is given. Methodology. The issue of resuming automobile traffic is an important task for the resumption of logistical state and local movements. Examples of restoration of artificial structures are given. It also shows the use of modern technologies, mechanisms, and methods of restoring structures on the bypass or on the old axis of the bridge. Findings. The main elements of the bridge over the Irpin river located on the public highway of state importance Ib technical category M-06 Kyiv-Chop (to the city of Budapest via the cities of Lviv, Mukacheve, Uzhhorod) were destroyed by mechanical damage as a result of hostilities in Ukraine. The characteristics of the destruction do not contribute to the restoration of the artificial structure on the existing axis of the structure. The restoration of the bridge was carried out on a short detour – 50 m downstream of the Irpin River. Originality. Today, the need to restore artificial structures arises in connection with their destruction during the war and after disasters of a natural, man-made, and military nature. There is an urgent need to study and implement the experience of restoring the transport infrastructure and construction of fortifications, its distribution among the personnel, the wide implementation of the lessons learned in the training process of the units of the State Special Transport Service. Practical value. The practical result of the use of reserve span structures of small and medium-sized railway bridges was obtained, which confirms the universal possibility of using the structures of the inventory bridge property, not only for conducting restoration works on the railway, but also for the restoration and construction of a temporary road bridge.
Purpose. The staged connections of the stringers of railway bridge track-way have the simplest design, but some design flaws result in numerous defects. The purpose of this work is an investigation of the previously proposed methods of strengthening the support node for the stringers of the track-way of a staged communication, as well as investigation of the work of the reinforcement proposed by the author. Methodology. The author analyzes the condition of metal bridges operated on the railway. It was found that the decisive element in determining the load capacity of the entire bridge are the stringers of the track-way. To achieve this goal, the author analyzed the stress-strain state of the support node of the stringer on the cross-bar without and with reinforcement using the finite element method. The discovered rational parameters of the proposed reinforcement unit. The calculations were performed in Selena software. Findings. Stress-strain state of the connection point of the stringers with the floor beamsnode on condition of their staged position was obtained and analyzed. The author selected the rational parameters of the reinforcement elements of the stringer support node for the staged communication and analyzed stress-strain state of the new connection node of the stringers with the floor beams at their staged location based on typical spans of Proiektstalkonstruktsii LLC (PSK). The analysis shows that after the proposed reinforcement, the maximum stresses in the horizontal legs of the flange angles of the stringers and floor beams, which destroyed the structures, decreased by 43–73%. Originality. The work analyzes the stress-strain state of metal stringers of the track-way of the staged location taking into account the joint work of stringers with load-bearing trusses, as well as the stress-strain state of the proposed reinforcement of the support node of metal stringers with the identification of rational parameters. Practical value. This method of repair with reinforcement is recommended as the most rational for a bridge over the Inhulets river at 109 km of the Verkhivtseve – Dolynska Railway (contract No. 94/2011–TsTekh–177/2011–ETU dated 09/30/2011). Based on these results, a patent for utility model No. 109806 dated 09/12/2016 was issued.
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