"Вестник МГСУ"

Presently, no uniform methodology of identification of optimal costs of construction of gas distribution networks is available. The amount of work, and, hence, its cost, are identified empirically; therefore, they are insufficiently substantiated by feasibility studies. At best, the problem of optimization is reduced to simple examination of various options.
The problem to be resolved by the method of search optimization may be stated in the following manner:
Two consumers are to obtain access to the gas supply. Their positions in the arbitrary coordinate system are available (; ). The high pressure gas distribution line of a gas distribution network is located at some distance from the aforementioned consumers. It can be represented as follows: = +. Gas control unit installation is required to assure gas pressure reduction.
Goal 1: positioning of a gas control unit to assure the lowest possible cost of the gas distribution network construction.
Goal 2: solution to the above problem turns more complicated, if the line of the gas distribution network required to connect the designed gas pipeline extension is long. In this case, besides the identification of the optimal coordinates of a gas control unit, it is also necessary to find the point of connection to the gas control unit, for the cost of the gas distribution network to be as low as possible.
Goal 3: some sections of gas distribution networks pass through or over natural or artificial barriers. In the event of such restrictions, the search for the optimal point of connection to the gas control unit turns more labor-intensive and challenging.
To sum up the above statements, the authors demonstrate that rational design of gas distribution networks brings essential economic benefits.

Generation of objectives should take account of the requirements of cost efficiency, technological effectiveness, reliability and safety. Complex objectives include the production cost of a reinforced concrete slab, operating costs and risks.Possibility of an emergency situation should be taken into account while calculating and constructing elements. The most reasonable way to minimize the damage caused by an emergency situation is to analyze the failure. A risk is defined as a probability of structural failure with implications of a certain level taking place within a certain period of operation. The damage caused by the total or partial destruction of a concrete slab is calculated on the basis of its residual cost, as well as the lowest required expenses for its repair and reconstruction. The «R – S» (risk–damage) function is most closely approximated by an exponential curve. Typically, reduction of the risk value leads to the cost increase of the construction. On the other hand, the risk increase may result in the structural failure in a shorter period of time. The proposed objective function offers the most adequate evaluation of the cost of designed projects considering the probability of emergency situations.

The presented article considers the following complex of tasks. The main stages of the life cycle of a building construction with the indication of process entrance and process exit are described. Requirements imposed on steel constructions are considered. The optimum range of application for steel designs is specified, as well as merits and demerits of a design material. The nomenclature of metal designs is listed - the block diagram is constructed. Possible optimality criteria of steel designs, offered by various authors for various types of constructions are considered. It is established that most often the criterion of a minimum of design mass is accepted as criterion of optimality; more rarely - a minimum of the given expenses, a minimum of a design cost in business. In the present article special attention is paid to a type of objective function of optimization problem. It is also established that depending on the accepted optimality criterion, the use of different types of functions is possible. This complexity of objective function depends on completeness of optimality criterion application. In the work the authors consider the following objective functions: the mass of the main element of a design; objective function by criterion of factory cost; objective function by criterion of cost in business. According to these examples it can be seen that objective functions by the criteria of labor expenses for production of designs are generally non-linear, which complicates solving the optimization problem. Another important factor influencing the problem of optimal design solution for steel designs, which is analyzed, is account for operating restrictions. In the article 8 groups of restrictions are analyzed. Attempts to completely account for the parameters of objective function optimized by particular optimality criteria, taking into account all the operating restrictions, considerably complicates the problem of designing. For solving this task it can be offered to use informational technologies and opportunities of automated systems. For this purpose it is necessary to develop the automated system of steel designs, allowing to consider some criteria of optimality and a wide range of the restrictions for steel structural designs. This will allow to accelerate projection process, to reduce labor input of a designer and essentially increase the quality of design solutions for steel designs.

Materials consumption rate is used by many authors as the criterion for the assessment of the economic efficiency of gas distribution networks in the course of their design. No doubt that control over the materials consumption rate is of particular importance. However, we believe that it represents one of several constituents of the overall cost of a gas network piping project. Labour expenditures and earth works that are, to some extent, dependent on the diameter of a pipeline, should also be taken into account. Presently, metal and polyethylene pipes of standard diameters are used in gas network development projects. Diameters of pipes of external gas distribution networks are rounded up to the closest standard diameter of pipes as a result of a hydraulic calculation.
The cost of construction of a gas pipeline has multiple constituents that may be clustered into three principle groups:
1) earth works,
2) piping;
3) cost of materials.
Calculation of the cost of construction of low and medium pressure pipelines to be made of steel and cross-linked polyethylene was performed to find out the cost of a pipeline.
The calculations were made in the basic prices of the year 2000 adjusted to the figures of April 2011, given the standard piping conditions in a settlement within central Russia. The data were interpolated by means of a quadratic function.
On the basis of the above data, a comparative analysis of capital expenditures in respect of steel and polyethylene piping may be performed.
The research also contemplates the structure of expenses associated with the piping of gas distribution networks. Mathematical equations have been derived to perform sufficiently accurate calculations of costs of construction of various types and various lengths of gas pipelines.

The principal mission of structural design consists in the development of economical though reliable structures. Any safety-related improvements boost the cost of a structure, while any reduction of costs involves higher risks. The objective of any structural designer is to pinpoint the optimal structural parameters among the whole variety of solutions that fall within the range of the pre-set design requirements and minimal risks. Selection of the optimality criteria applicable to reinforced concrete structures is to be based on a set of requirements, including low costs, technological efficiency, safety and observance of limits imposed onto the expenditure of material resources and the workforce.
The author suggests splitting the aforementioned parameters into the two groups, namely, natural parameters and value-related parameters that are introduced to assess the costs of development, transportation, construction and operation of a structure, as well as the costs of its potential failure. The author proposes a new improved methodology for the identification of the above parameters that ensures optimal solutions to non-linear objective functions accompanied by non-linear restrictions that are critical to the design of reinforced concrete structures. Any structural failure may be interpreted as the bounce of a random process associated with the surplus bearing capacity into the negative domain. Monte Carlo numerical methods make it possible to assess these bounces into the unacc eptable domain.

Subject: the subject of research of the author is elements, interrelations, processes that unite participants of investment-construction projects (ICP) at the stage of designing and functioning of organizational structures of ICP. Research objectives: the purpose of the study is to formulate conceptual proposals for developing the foundations of an objective mechanism for assessing the reliability of enterprises participating in ICP as elements of the organizational structure on the basis of analysis of Russian and international practices for monitoring the status of organizations and enterprises of various profiles and industries. Materials and methods: in the process of research, we analyzed the most fundamental methods and methodologies for evaluating consistency of organizations and enterprises developed and used by various rating agencies, regulating organizations, associations and state authorities. Results: analysis of the most frequently used methods and approaches to assessing consistency of organizations allowed us to establish conclusions about shortcomings of the methodologies as well as high complexity of their implementation and application for assessing the reliability of enterprises of the construction industry. A key drawback of existing approaches to enterprise reliability assessment is the significant concentration of researchers’ attention on assessing the financial and business performance of organizations’ activity at the expense of the assessment of organizational, technological, social and non-financial aspects. Conclusions: a way out of the existing contradiction is the use of already existing forms and methods of statistical observations of the activities of organizations developed by the Rosstat of Russia. Adaptation of the monitoring process, updating the content of the forms of observation can be used to develop a universal mechanism for assessing the reliability of enterprises participating in ICP.