The specificity of the problem of reconstruction of the Divorius bridges of St. Petersburg is determined by the fact that many bridges are under the protection of the state as monuments of history and culture, or are elements of the current urban environment or architectural ensembles. Recall that the construction of divorce bridges in St. Petersburg began simultaneously with the foundation of the city. The first Petrovsky (Ioannovsky) bridge across the Kronverk, on which building materials were brought up for the construction of the fortress (Petropavlovskaya) on the hare island, had a divorce flight. The following measures taken during the operation of these bridges are possible, each of which requires a special approach for its implementation: – maintaining the old bridges in the serviceability of the old technical condition and possessing acceptable qualities in the carrying capacity and size of the carriageway (throughput): – reconstruction of the old bridges that do not have sufficient carrying capacity and throughput or in unsatisfactory technical condition; – the reconstruction of the structures rebuilt in the process of long -term operation, the return of the historical appearance to them; – restoration of the elements of architectural decoration of bridges in the unsatisfactory state. The most complex tasks, as a rule, arise during the reconstruction of the divorce bridges due to their multicomponent and structural complexity. In addition, almost every bridge is individual both in its scheme and in constructive features. Analysis of the accumulated experience allows us to distinguish the following options for reconstruction of the divorce bridges: the reconstruction of temporary (wooden) bridges to capital -type bridges; a complete reconstruction of capital structures, including the divorce and stationary parts of the structure; complete reconstruction of the divorce span; partial reconstruction of the divorce span. In some cases, the decisions adopted during the design of the divorce spans turn out to be unsuccessful, which can lead to difficulties during operation (exchange bridge), and sometimes accidents (bridge to them. Alexander Nevsky). In this case, the reconstruction should be aimed at improving the characteristics of the divorce spans and increasing their reliability.
