OPTIMIZATION OF CALCULATION SCHEMES

Any calculation is preceded by the stage of creating a design diagram of a real structure, which would most accurately correspond to real operating conditions. The more optimally the design scheme is drawn up, the less laborious the stages of calculation and design of the corresponding structure will be. There are practically no results of using this approach when calculating building structures. This article attempts to show the possibility and expediency of using the "Search for solutions" (add-on for Microsoft Excel) at the stage of choosing the optimal parameters of the design design schemeAny calculation is preceded by the stage of creating a design diagram of a real structure, which would most closely correspond to real operating conditions. The more optimally the design scheme is drawn up, the less laborious the stages of calculation and design of the corresponding structure will be. If the efficiency criterion is a linear function, and the variables in the constraint system are also linear, then such a problem is a linear programming problem. Of the listed methods of mathematical programming, the most common and developed is linear programming. To illustrate the idea of the proposed approach, a simple statically definable truss on two supports was deliberately chosen. This is done so that the idea of the proposed approach is not lost due to the complexity and cumbersomeness of the calculations. This article shows the possibility and feasibility of using the "Search for solutions" at the stage of choosing the optimal parameters of the design design scheme. After the design scheme has been defined, more powerful conventional means of calculating building structures can be involved for its complete calculation.

INCREASING THE EFFICIENCY OF THE ROOF PURLIN SYSTEM

In the article, the authors consider one of the ways to solve the problem of reducing metal consumption and increasing the efficiency of metal structures by choosing an effective static scheme. The choice of the appropriate scheme is carried out for the most common elements of metal structures - beams, which also include roof purlins. To cover the industrial building of the seaport, discontinuous and continuous stringer systems are being developed and their efficiency is analyzed in terms of metal consumption and labor intensity.

MATHEMATICAL MODELING OF THE COVERING OPTIMIZATION OF THE ROUND BUILDINGS IN A PLAN WITH A RADIAL BEAM POSITION

The article presents the results of optimization of the angle between radial beams in the floor of a circular building in the plan. On the one hand, they rest on the central post, and on the other, on vertical supporting structures along the circle. Steel decking is laid on the beams. The angle between the beams is determined so that the mass of the beam and the deck is minimal. This angle is considered optimal. To solve the problem, the target function of the cost of flooring and radial beams per unit floor area is used. This function depends on the angle between the beams. Using mathematical methods of differentiation, the minimum of the objective function and the corresponding value of the optimal angle were found. The thickness of the flooring was determined on the basis of ensuring its rigidity. It is assumed that composite welded radial beams have I-beams with two axes of symmetry. The height of the beam corresponds to the equality of the areas of the shelves and the wall. The problem of determining the optimal angle between the beams was solved on the basis of ensuring the strength of the beams under normal stresses. In the design diagram of the beam, a triangular distributed load is adopted. The dimensions of the cross-section of the beam were determined based on the equality of the required and actual moments of resistance, and were included in the target cost function. The study took into account that the deflection of the beam at the optimal angle between them can exceed the limiting standard value. Based on the solution of the system of equations of strength and stiffness, a formula is obtained for the minimum angle between the beams from the stiffness condition. The carried out mathematical studies have shown that at the optimal angle between the beams, it is possible to ensure its rigidity. This is possible when the flexibility of the beam wall exceeds a certain minimum value. Analysis of the formula for the minimum value of the wall flexibility showed that it is proportional to the design steel resistance to the sixth power. Therefore, to ensure that the deflection of the beam does not exceed the limiting value at the optimum angle, it is necessary to use low strength steel. To confirm the practical feasibility of using the proposed method, the problem was solved with certain numerical data. The results obtained have confirmed that the problem has a practical meaning at a relatively low steel strength. In addition, it turned out that the optimal angle between the beams does not depend on its span.

JOINT WORK OF STEEL AND BASALT PLASTIC REINFORCEMENT WITH CONCRETE AS PART OF BEAM STRUCTURES

Experimental data on strength, deflections and cracking in beams are presented. Beams are made with dimensions 2000x200x100mm with steel and basalt-plastic (BFRP) reinforcement. They have been tested for static and low-cycle reloading. The results of studies of the main parameters of the performance of research elements are presented in the form of the corresponding experimental-statistical dependences for the actions of operational and destructive loads with the same design factors. With the help of stochastic and graphical analysis, the influence of the type of reinforcement and design factors on the strength and deformation characteristics, as well as on the crack resistance of experimental samples - beams, is estimated.

BIM-TECHNOLOGY METHOD AND MODELS IN THE DESIGN OF THE AQUAPARK DOME STRUCTURE WITH WOODEN ARCHES

Тhe issues of designing a multi-volume dome structure for a water park using wooden arches as load-bearing structures are сonsidered. The complexity of the volumes and their joining lines, as well as the requirement to perform non-linear analysis of large-span timber elements at the request of Eurocode 5, make an information model with elements of BIM-technology necessary. It is noted that design using this technology is developing in the direction of taking into account all stages of the structure life cycle. Wood Information modeling is the most prepared for the use of BIM-technologies. This is due to the high factory readiness and complex digital technologies for the manufacture of modern wooden structures elements. During the design, an information model was formulated in the SAPFIR software package with the subsequent possibility of importing the model into the LIRA-SAPR software package. Additional steps were used to build the model: creating a 2D template in AutoCad with reference lines and the location of rigid walls on which the coating rests, and importing drawings into SAPFIR as a dxf-underlay; for all elements of the system located in the local coordinate system, auxiliary lines were built for the correct orientation of the plane in space; loads on curved surfaces were calculated in the PC Expri. For the further development of the nodes, 3D modeling was used with the transfer of the information model to the Tekla Structures PC as a specialized environment for the constructive section of the project. The presented calculation of a complex dome structure using wooden arches summarizes the approaches to the development of unique forms of structures using wood. The use of information models made it possible to reduce the time spent on design, to optimize the drawings, and also to significantly increase the complexity of the architectural and structural design of the structure and the design model, taking into account the nonlinear effects of wood.

CONCERNING THE SELECTION OF DESIGN AND TECHNOLOGY SOLUTION FOR A MINI-HOTEL CONSTRUCTION

The article considers the features and advantages of innovative design and technology solution for mini-hotels construction in the framework of eco-tourism development. The examination of the main potentials of eco-tourism development in Ukraine and Moldova, are presented on the example of the city of Tiraspol. Space planning and design features of the project "Dubovaya Roshcha" tourist complex in Tiraspol, Moldova are characterized there. This article presents a method of multicriteria analysis of design and technology solutions based on the factor evaluation of decision options of low-rise building construction. In this examination the main factors influencing the choice of building structures were emphasized.

CALCULATION OF INTERMEDIATE SUPPORTING PARTS OF INSEPARABLE PERFORATED BEAMS IN THE SOFTWARE COMPLEX «LIRA»

Due to the simplicity of design and manufacture, as well as reliability during operation, beams are one of the most common elements used in industrial, civil and public construction. The most rational cross-section of metal beams are rolled I-beams with inclined or parallel inner faces of the shelves, the predominant use of which is due to the value of the core distance, which is twice as much the same value for a rectangular section and almost three times for a round section. This figure is even higher for perforated profiles obtained from conventional rolling beams, which allow you to compose sections with increased values of moments of inertia and moments of resistance without increasing material consumptions. For inseparable beams, an additional significant factor influencing on their bearing capacity, is the structural design of the intermediate support part. The aim of these researches is to study the stress-strain state of inseparable perforated beams of I-beam profile of different heights in areas near the intermediate support, the design of which is made without a transverse stiffening rib placed on the axis of the support, and with unwelded holes to the left and right of the support under the action of evenly distributed load in the software complex "Lira". The objectives of the study are to establish the actual values of stresses and strains in the characteristic cross sections of the inseparable perforated I-beam, which occur on the intermediate support, and perform a comparative analysis of numerical studies obtained in the software complex "Lira" for intermediate support node beams of different heights for actions of different magnitudes of loads. The analysis of the obtained diagrams of normal stresses was carried out, which showed that for the proposed design of the support part of the beam, the cross-sections with holes directly to the left and right of the support are calculated. The conclusion about necessity of carrying out further experimental-theoretical researches of various types of support parts of beams for the purpose of development of a complex technique of their calculation and recommendations on definition of rational scope of application of each of them is formulated.

TECHNOLOGY PROVIDING SECONDARY PROTECTION METAL STRUCTURES AGAINST CORROSION UNDER AGGRESSIVE IMPACT OF METALLURGICAL PRODUCTION

Research is aimed at the formation and development of innovative developments to increase the metal structures corrosion protection, as an important means of ensuring the quality and safety industrial facilities. The method determining the corrosion destruction signs, the procedure of monitoring and carrying out measures to diagnose the technical condition of lattice metal structures according to the level of corrosion hazard were adopted. The nomenclature indicators and control methods (conformity assessment) of determining parameters primary and secondary protection metal designs against corrosion is established. During this study, the lattice structures operational condition loader crane’s girder structure was considered. It is revealed that operation of the crane is carried out in difficult production conditions operating environment’s aggressive influence in combination with considerable dynamic loadings working operations loading technological process, unloading, sorting (averaging) of ore yard’s charge of blast furnace shop. Based on the study structures corrosion condition and operating conditions, measures have been developed to increase the durability ore-grab crane of the reloader. Based on the analysis of the principles of the ISO 9001 process approach, the development and implementation design solutions to extend the structures service life in aggressive environments of metallurgical production. It is proved that the procedure of making constructive and technological decisions, performance works on increase corrosion resistance promotes maintenance conditions of resource saving and technological safety industrial constructions. The principles process is offered to develop and implement design measures to extend the service life of structures in aggressive environments metallurgical production are proposed. Constructive and technological measures to ensure durability in accordance with the requirements of the building structure corrosion risk have been developed, which are determined by the critical indicators metal structures protection in the conditions corrosion influences within their limit values.

MODERN CONSTRUCTION SOLUTIONS FOR PRESTRESSED CABLE DOMES AND WAYS TO IMPROVE THEM

To create fundamentally new innovative large-span structures of buildings and structures coverings, modern design solutions of prestressed cable domes of the Tensegrity type are considered. The service life of the first built Tensigrity domes is only 35 years. These are fairly new, effective structures that require careful study and use of modern scientific approaches for their design using software systems, since their work under load and the construction process are quite complex. The design analysis and erection of self-stressed structures is based on the invention of an equilibrium structure, the so-called tensegrity form. The search for the shape is multidimensional and consists of the stage of computational analysis of a self-stressed dome for the equilibrium position of elements and their nodes, selection of the most stable and rigid structure, as well as taking into account possible unfavorable loads during operation and the initial load in the elements from the application of prestressing. To determine the shape of cable domes, a nonlinear programming problem with given axial forces is formulated, which can be considered as the problem of minimizing the difference in the total strain energy between the elements of the cables and struts under constraints on the compatibility conditions. The first step in calculating the prestressing of a cable dome is to assess the feasibility of its geometry. The possibility of forming a cable dome of negative Gaussian curvature is considered and a method for calculating the prestressing for this new shape is investigated. The proposed method is effective and accurate in determining the allowable prestressing for a cable dome with negative Gaussian curvature and can be used for other types of prestressed structures. The new directions for the development of effective constructive solutions for large-span coatings are presented, including a suspended-dome structure, which combines the advantages of a mesh shell and a cable dome. Special attention should be paid to experimental studies on models of tensegrity domes, the results of which demonstrate the positive and negative aspects of the behavior of structures under load, the process of their erection, as well as the possibility of control and restoration during operation.

THE DETERMINATION OF THE RESIDUAL LIFE OF BUILDING STEEL STRUCTURES BY THE RELIABILITY INDEX INDICATORS

In order to assess the operational safety of steel constructions, the paper analyzes the principles of calculating the safety of structural steel constructions with consideration for the reliability index β at all phases of constructions operation and the design fundamentals of the reliability index β for both new constructions (at the design stage) and structural steel constructions in the conditions of the long-term operation. The task of safety and reliability calculations, first of all, consists in assigning normalized safety parameter values, i.e. normalizing the reliability index, the value of which should be strictly related to the consequence classes (CC), which are determining for setting the reliability coefficients for further calculations while designing the constructions. The article considers the calculation values β of the reliability index for constructions operated beyond the time limit for operation, with accumulated defects and damages. To improve the mechanism for calculating the reliability index value for the constructions operated beyond the maximum operating limit, with accumulated defects and damages, several tasks were set to determine such values β of the reliability index below which the construction is no longer considered to be operational and to define the reliability index values β for possible performance of renovation works (reconstruction, refurbishment) to strengthen and extend the remaining structural lifetime. Thus, emphasizing all of the aforementioned, the main conclusions to the article should be specified: at the stage of solving the issue of calculating the reliability index for structures being operated over the projected service life, with damages and initial defects accumulated during the operation period, it is required to perform their review and determine two main criteria for solving the issue of determining the reliability index, namely: to set such values of the reliability index below which the structure will be no longer operational, to define and set such values of the reliability index at which it is possible to carry out renovation works on steel structures, their reconstruction or repair. Considering the possibility of changing the reliability index compared to a new structure, given that the residual service life may be shorter than the design one, taking into account the economic factors and factors of probability of losing a person’s life, setting of such reliability index values is necessary for further possibility of the service life extension of a structure and determination of its residual life.