Introduction. The experience of operation of reinforced concrete span structures of bridges from the time of their use shows the need for their constant improvement.
Due to the use of pre-tensioning of reinforcement in reinforced concrete span structures of bridges, it was possible to increase the crack resistance of such structures and operational reliability. This is especially relevant when it is necessary to increase the length of spans of reinforced concrete span structures.
Problems Statement. The use of monolithic prestressed span structures with tension on concrete (post-tensioned systems) is the newest for Ukraine. They have many advantages compared to prefabricated prestressed reinforced concrete. But it is necessary to solve a number of problems in the design and construction of such structures in order to achieve the efficiency of structures that would serve the designed term, using all their advantages.
Therefore, the study of such structures, assessment of their stress-strain state will allow in the future to find solutions for their improvement, development of appropriate calculation recommendations, construction of such structures.
Purpose. Study of the stress-strain state of the structure of the monolithic non-separated prestressed span structure of the overpass with tension on concrete (post-tensioned system) in the city of Kherson.
Materials and Methods. The survey and testing of the flyover overpass over the railway in the city of Kherson was carried out. The researched span structure of the overpass is a girder continuous reinforced concrete monolithic prestressed structure, reinforced with prestressed beams with tension on the concrete («post-tensioning» technology).
The study of the stress-strain state of the span structure included establishing the parameters of spatial work and the stress-strain state of span structure elements by measuring absolute deformations (deflections), recording acoustic emission (AE) signals under the action of static load.
Trucks were used for the test load. The maximum value of the test load was 137.74 t when the cars were installed within the spans with the maximum possible approach of them in the transverse direction to the edge of the right side of the carriageway, in the longitudinal direction, the cars were positioned so as to load the middle of the tested span of the structure with the maximum load.
Results. On the basis of the conducted study of the span structure of the overpass, the parameters of its spatial operation and stress-strain state were determined by measuring absolute deformations (deflections) under the action of static load. Based on the results of research, the value of the design factor k was determined, which is in the range of 0.44 ... 0.93.
The values of transverse distribution coefficients (CPR) for beams were experimentally determined and a numerical analysis of real-life and analytical spatial work of the girder structure based on transverse distribution coefficients was carried out.
As a result of the study of the structure using the acoustic emission method, it was established that at the time of testing the structure of the span structure did not have defects in the materials that would have a tendency towards emergency development.
Conclusion. Real-time studies of a transport structure of considerable length with a monolithic prestressed span structure (post-stressed system) showed the correctness of theoretical approaches to the calculation and construction of such a structure.
The parameters of its spatial operation and the stress-strain state of the elements have been established on the basis of the conducted studies of the span structure. The results of the analysis of the received data proved the good spatial operation and rigidity of the span structure, as well as the compliance of the main parameters of the structure with the current norms regarding the design of bridges.
