The article deals with the creation of continuous metal and monolithic reinforced concrete bridge spans, which are the most effective. Efficiency is achieved by finding opportunities for the unification of structures with the most successful options for providing them with the required load-bearing capacity with the lowest cost of building materials. The bending moments that occur in the sections of a continuous structure are distributed more evenly and take on smaller values in the span than in a split structure. However, the efficiency of continuous structures can be further improved by introducing a certain coefficient of the length of the extreme spans of the bridge relative to the average ones. This allows you to achieve equality of the reference or span bending moments. As a result, the design will work in such a way that it will be possible to build the bridge span as if from three types of unified blocks, which will reduce the complexity and cost of construction work. As an example, in this case, the ratio of spans and the corresponding division into blocks for four-span continuous bridges are determined.

In modern bridge construction, on the one hand, there are increasing trends towards increasing bridge spans, which requires reducing the weight of structures. On the other hand, the use of structural elements made of various composite materials is expanding, which allows to significantly reduce the weight of the bridge structures as a whole. However, the creation of new forms of span structures of bridges requires more detailed calculations in order to optimize such forms, in particular the role of calculating the dynamic impact, because with increasing spans and weight loss, increases design flexibility and sensitivity to dynamic loads. In the present paper, the problems of solving an incomplete algebraic problem of eigenvalues and eigenvectors are considered. To increase the accuracy of the calculation and exclude the use of high-order matrices, a method of sequential reduction of the stiffness and equivalent mass matrices is proposed. The method is based on the construction of partial systems using a static transformation, followed by the solution of its own problem for the partial system. In the process of solving this problem through the eigenvectors of the system, the minor unknowns are reduced to the main ones. Dynamic reduction showed high calculation accuracy..

The method of the gas turbine unit and the waste heat boiler gas-air duct circuit modernization is considered. The operation scheme of a gas turbine unit and a waste heat boiler with the use of a catalytic afterburner has been shown. There is also a decrease in nitrogen and carbon oxides in the exhaust steam-and-gas mixture due to a deeper cleaning process of the exhaust steam and gas mixture, which leads to an increase in the service life of the waste heat boiler [1]. A more complete process of heat transfer to the coolant in the furnace section of the boiler is performed due to the cleaner steam and gas mixture in the waste heat boiler and due to a decrease in the boiler tubes growth formation by the combustion products. This makes it possible to reduce the cost of fuel consumption by gas burners of the waste heat boiler. Also, as a result of this process, it is possible to reduce fuel consumption for the needs of heating the feed water and the auxiliary needs of a power unit. This article proposes to use lattice devices in the afterburner, treated with active substances by the ion implantation method, as one of the most promising ways of modifying lattice surfaces [2 – 6]. These processes occurring when the steam-and-gas mixture passes through the afterburner, allow increasing the cycle efficiency factor and limit of maximum allowable concentrations (MAC) emissions for various options for the exhaust steam-and-gas mixture utilization of a gas turbine unit (GTU) and heat supply to the waste heat boiler.