OPTIMAL CONSTRUCTION AND TECHNOLOGICAL SOLUTION FOR RECONSTRUCTION OF A CITY PIPELINE AND THE RESULTS OF ITS TESTS

Purpose. To once again draw the attention of bridge owners and bridge experts to the problems of reconstruction of long-term bridges and on a concrete example of reconstruction of a rather problematic city overpass operated for more than 60 years to shows that with the optimal structural and technological solutions of the reconstruction received a restored bridge, and its operational and technical and economic indicators which according to the requirements of the National Building Norms completely correspond to the new bridge, but the reconstruction cost and the lead time are greatly reduced. Methodology. To achieve this purpose over the past ten years of operation of the overpass conducted three inspections and full-scale static tests. It is determined that most of the existing reinforced concrete structures, although defective and in need of repair, can be used for further operation after reconstruction, provided they are reinforced. Worn out non-repairable structures that needed to be replaced were also found. Results. According to these initial data, a reconstruction project was developed using scientific and technological structure developments of the Branch Research Laboratory 88 of Lviv Polytechnic National University for the reconstruction of bridges. The span structure has been expanded to 4 lanes from the size G-10.5 + 2 × 0.9 m to the new G-16.5 + 2 × 1.5 m in a combined way – symmetrical completion of two new beams with their support on the extended support and installation of a reinforced concrete extension board with cantilever overhangs 2.7 m long. The most damaged boundary beams were replaced with new ones, designed for normalized temporary loads A15 and NK-100. For further operation the other existing beams are reinforced in one of the least expensive ways – by changing the static scheme from the existing split to the new clamped on the supports frame-inseparable. A set of repair works is provided to ensure the normalized durability of the reconstructed overpass. The scientific novelty is to develop a method for determining the experimental Coefficients of Transverse Distribution of Bending Moments (CTDM) and external loads (CTD) based on the results of tests of the span structure. The possibility of applying the method of elastic supports for the spatial calculation of span structures with beams of different stiffness is confirmed. Practical significance. The use of optimal design solutions for the reconstruction of existing span structures: reinforced concrete billboard with large cantilever overhangs to expand and change the static scheme to strengthen the beams of span structures.

From Mises and Hayek to the Planned and Mixed Economy. Planning Criteria, Basic Income, Guaranteed Job

Arguments of Mises and Hayek, who opposed the planned economy (PE), are used in the paper as a starting point for establishing the objective area of effective application of the PE. The abstract model of PE, based on the definitions of Mises and Hayek, leads to the conclusion that for the effective use of PE, it must be a part of mixed economy and it must produce a limited amount of essential goods of irreducible demand. These goods must be distributed among all members of society free of charge, evenly, without competition. Examples of a mixed economy are given that meet this requirement. Calculations of the personal benefit in the transition to a mixed model of the economy have been carried out. The positive and negative qualities of the planned and market methods of organization are considered. Mixed economy model combines these qualities in optimal construction. An analytical framework has been introduced for the construction of product characterization curves. Such curves provide criteria for determining the efficiency of manufacturing of this product in a planned economy. The general economic prerequisites for the usability of the PE are clarified. The applicability and advantages of the PE for the organization of the universal basic income (UBI) system are demonstrated. The possibility of using PE to solve the problem of guaranteed employment is mentioned.

Integration of Mixed-Integer Nonlinear Program and Project Management Tool to Support Sustainable Cost-Optimal Construction Scheduling

This paper presents the integration of mixed-integer nonlinear program (MINLP) and project management tool (PMT) to support sustainable cost-optimal construction scheduling. An integrated structure of a high-level system for exact optimization and PMT was created. To ensure data compatibility between the optimization system and PMT and to automate the process of obtaining a cost-optimal schedule, a data transformation tool (DTT) was developed within a spreadsheet application. The suggested system can determine: (i) an optimal project schedule with associated network diagram and Gantt chart in continuous or discrete time units; (ii) optimal critical and non-critical activities, including their early start, late start, early finish, late finish along with total and free slack times; and (iii) minimum total project cost along with the allocation of direct and indirect costs. The system provides functionalities such as: (i) MINLP can be updated, and schedules can be re-optimized; (ii) the optimal schedule can be saved as a baseline to track changes; (iii) different optimization algorithms can be engaged whereby switching between them does not require model changes; (iv) PMT can be used to track task completion in the optimized schedule; (v) calendar settings can be changed; and (vi) visual reports can be generated to support efficient project management. Results of cost-optimal project scheduling are given in a conventional PMT environment, which raises the possibility that the proposed system will be more widely used in practice. Integration of MINLP and PMT allows each software to be used for what it was initially designed. Their combination leads to additional information and features of optimized construction schedules that would be significantly more difficult to achieve if used separately. Application examples are given in the paper to show the advantages of the proposed approach.

EFFICIENT ENGINEERING IN DEVELOPMENT OF CONSTRUCTION SECTOR COMPETITIVENESS

The COVID-19 pandemic has really become a real shock for the whole world. The way of life has changed not only for people, but also for companies in various industries. Today, the real estate market, like many other industries, is in conditions of economic instability. The study highlights the problems faced by the construction sector in the current conditions of the coronavirus pandem-ic. One of these problems is the sustainable competitiveness of construction and its compliance with new consumer preferences. Aim. The study of the influence of engineering solutions and other fac-tors on the competitiveness of construction in modern economic conditions, the definition of key criteria. Development and description of the decision-making methodology for choosing the optimal construction enterprise from the point of view of competitiveness. Materials and methods. The methods of system analysis, optimization methods, hierarchy analysis and decision theory are ap-plied in the work. Within the framework of the proposed methodology, the author's method of identifying key competitiveness criteria has been developed. Since the problem of choosing the optimal solution from among the alternatives is based on a multi-criteria approach, the use of this method is quite appropriate. The template for the formation of the methodology was identified based on the analy-sis of existing research in this area. Results. The author summarizes and supplements the criteria and factors affecting the competitiveness of construction organizations in the study. The author's method of making a decision on determining the optimal construction enterprise from the point of view of competitiveness based on the criteria considered by the author is presented. This technique includes several stages: 1) forming a goal; 2) formation of criteria by which organizations will be evaluated; 3) calculation of criteria for each organization and bringing them to a homogeneous type of data; 4) building a tree of goals and a matrix of priorities; 5) Determining the values of priority vectors for each organization under study. Conclusion. The total influence of criteria and engineering solutions on the competitiveness of construction is determined. In this regard, the implementation of the con-struction project should be carried out taking into account the strategic goals of the organization and binding to the identified criteria. The proposed methodology is developed for Russian construc-tion companies operating in modern economic conditions.

A Learning-Based Methodology to Optimally Fit Short-Term Wind-Energy Bands

The increasing rate of penetration of non-conventional renewable energies is affecting the traditional assumption of controllability over energy sources. Power dispatch scheduling methods need to integrate the intrinsic randomness of some new sources, among which, wind energy is particularly difficult to treat. This work aims at the optimal construction of energy bands around wind energy forecasts. Complementarily, a remarkable fact of the proposed technique is that it can be extended to integrate multiple forecasts into a single one, whose band width is narrower at the same level of confidence. The work is based upon a real-world application case, developed for the Uruguayan Electricity Market, a world leader in the penetration of renewable energies.