This article discusses the technology of reconstruction of a metal arch bridge by reinforcing the structure with prestressed elements. The main metal beams were in unsatisfactory condition, the metal structures of the span below the level of the roadway slab are subject to deep layered corrosion up to the formation of through damage. To restore the bearing capacity of the main beams of the Nikolsky bridge across the Kineshemka river, their reinforcement is provided. The main task when performing the reinforcement of the main beams is the installation of new prestressed reinforced concrete beams directly inside the old metal main beams of the bridge with the regulation of forces in high-strength ropes. Due to the fact that the effort of high-strength ropes cannot be immediately brought to maximum design loads, a step-by-step prestressing scheme of ropes with synchronous sectional concreting of main beam compartments is proposed. The process of tension in the reinforced concrete beam of the main beams is carried out in two stages: stress at the end sections, where an anchoring system was created in four corners and then prestressing the main gift space with concreting sections between the pendants according to a specially developed scheme in the work design. Only fiber-reinforced concrete is used, and reinforcing stops were welded to work together with the inner surface of the main beams. Examples of reinforcing steel beams with steel strands on steel-reinforced concrete spans already existed, however, the transfer of force through a reinforced concrete inner beam was carried out for the first time in the world. After the main tie-in beams began to work together with a metal arch, it was decided to start repairing the cross-beams, which hold the reinforced concrete slab in the longitudinal direction, and themselves rely on the main beams. Some transverse beams were corroded to the point that they were holding onto a reinforced concrete slab, therefore NPP SK MOST developed a technology for prestressing the transverse beams with their jacking and subsequent shotcreting from all sides, and they were supported on the main beams, which were already ready for perception load. In conclusion, the authors confirm the effectiveness of the proposed technology; At the end of 2018, an examination and acceptance testing of the Nikolsky Bridge was carried out. The results of static and dynamic tests of the bridge indicate that the actual stress-strain state of the span structure is consistent with design values. The bridge can be taken under load NK-80. After the acceptance of the bridge structure by the working commission, traffic was opened for cars and pedestrians.
Reventing brittle hybrid high-strength reinforced concrete slab collapse due to punching shear using coal flyash substitution, tie wire fiber and polypropylene fiber
