Metallic Truss Research Articles

Створення бази комплементарних гнутозварних профілів решітчастих металоконструкцій

This article discusses the development of a database for complementary bent-welded profiles, which facilitates the automation of the design of lattice metal structures. The main focus is on determining the conditions necessary to create efficient and technologically optimized solutions for metal trusses, taking into account the local stability of elements and the limitations of technological connections. The methodology involves analyzing models of rectangular tube intermediate assemblies in Solid Works and processing the results in Microsoft Excel, which allows elements to be grouped into complementary profile combinations. This study helps to link technical constraints to the strength of elements and simplifies the selection of profiles in accordance with DSTU EN 10219-2:2019, minimizing under loading by up to 5%. The authors emphasize the importance of technological optimization in the design of metal structures, using modern software solutions to analyze and select optimal solutions. They emphasize the importance of integrating profile databases with design software, which significantly increases the speed and quality of design solutions. This work makes a significant contribution to the practice of designing lattice metal structures by providing engineers with tools for efficiently selecting profiles based on technical characteristics and constraints. The article concludes with an analysis of the results obtained and prospects for further research in this area. The authors discuss the possibilities of expanding the database to include additional profile parameters and developing more flexible design tools, which will allow for even greater technological efficiency and cost-effectiveness of metal structures. This approach opens up new horizons for innovation in the design of metal structures, contributing to the development of more sustainable and efficient construction.

A Comparative Analysis of Optimization Algorithms for Finite Element Model Updating on Numerical and Experimental Benchmarks

Finite Element Model Updating (FEMU) is a common approach to model-based Non-Destructive Evaluation (NDE) and Structural Health Monitoring (SHM) of civil structures and infrastructures. Its application can be further utilized to produce effective digital twins of a permanently monitored structure. The FEMU concept, simple yet effective, involves calibrating and/or updating a numerical model based on the recorded dynamic response of the target system. This enables to indirectly estimate its material parameters, thus providing insight into its mass and stiffness distribution. In turn, this can be used to localize structural changes that may be induced by damage occurrence. However, several algorithms exist in the scientific literature for FEMU purposes. This study benchmarks three well-established global optimization techniques—namely, Generalized Pattern Search, Simulated Annealing, and a Genetic Algorithm application—against a proposed Bayesian sampling optimization algorithm. Although Bayesian optimization is a powerful yet efficient global optimization technique, especially suitable for expensive functions, it is seldom applied to model updating problems. The comparison is performed on numerical and experimental datasets based on one metallic truss structure built in the facilities of Cranfield University. The Bayesian sampling procedure showed high computational accuracy and efficiency, with a runtime of approximately half that of the alternative optimization strategies.

Variation Coefficient of Metal Yield Strength in New and Long-Used Building Structures

Introduction. Non-destructive methods are most often used to assess the condition of the metal structure. Dangerous stress is determined by the value of the yield strength. This approach has weaknesses. This is, firstly, the probabilistic nature of the methodology (the minimum value of the indicator obtained during laboratory tests is entered into the regulatory and technical documentation). Secondly, the limitations on the number of samples should be overcome. Thirdly, the different duration of operation causes a significant difference in the mechanical characteristics of the metal, which to a certain extent complicates the long-term prediction of the condition of the structure. The presented work is designed to solve these problems within the framework of the study of new and long-operated facilities in the Rostov region. The scientific research objective is to analyze fatigue changes and determine possible degradation of the metal.Materials and Methods. The mechanical characteristics of the material under study were reliably described by the Weibull distribution law through the shear parameter (the minimum possible value of the characteristic) and the shape parameter (magnitude dispersion). For scientific research, the indentation method based on a modified Rockwell hardness estimation method was used as part of the work. A conical indenter was embedded in the surface, then the reaction of the metal was analyzed. To implement the method, an analog-to-digital converter and a laptop were used. For correlation analysis, intermediate characteristics were taken: depth, maximum and minimum velocities, maximum and minimum acceleration of cone insertion. A correlation was established with the mechanical characteristics determined by standard tensile and hardness tests of the metal.Results. Objects with zero and long-term operation were studied. The measurements were carried out in a warehouse, production site, stadium, bridge, Palace of Sports and on a power line support. From the group of new and used structures, one was selected for a detailed fixation of the values of yield strength. So, before the start of operation, the condition of three metal trusses of the warehouse was analyzed. It was established that the lowest value of the yield strength here was 240 MPa, the maximum was 345 MPa. On the power transmission line poles, which have been in operation for 43 years, the lowest recorded value of the yield strength was 235 MPa, the highest was 384 MPa. For each of the six structures, the minimum and average distribution of the metal yield strength values was given, and the coefficients of variation of this indicator were given. The recorded values were summarized in the form of a table. The average values for all new and used designs were calculated. Graphically presented data illustrate the growth of the coefficients of variation of the yield strength with increasing service life.Discussion and Conclusion. A comparative analysis of the obtained values of the yield strength of building structures of approximately the same strength class suggests that the influence of operating time can both increase and decrease the studied indicator. At the same time, long-term operation is a factor that increases the average value of the coefficient of variation. To monitor the strength capabilities of the structure, it is advisable to use a non-destructive method, selectively monitoring the mechanical characteristics of the elements before and during operation.

Instance and semantic segmentation of point clouds of large metallic truss bridges

Several methods have been developed for the semantic segmentation of reinforced concrete bridges, however, there is a gap for truss bridges. Therefore, in this study a state-of-the-art methodology for the instance and semantic segmentation of point clouds of truss bridges for modelling purposes is presented, which, to the best of the authors' knowledge, is the first such methodology. This algorithm segments each truss element and classifies them as a chord, diagonal, vertical post, interior lateral brace, bottom lateral brace, or strut. The algorithm consists of a sequence of methods, including principal component analysis or clustering, that analyse each point and its neighbours in the point cloud. Case studies show that by adjusting only six manually measured parameters, the algorithm can automatically segment a truss bridge point cloud.

Optimization of the Geometric Parameters of the Metal Truss

Abstract: This article is devoted to the optimization of the geometric parameters of the metal truss, and the following are studied in the article. Trusses belong to flat rod systems. The simplest structure is a truss consisting of rods spherically connected to each other. One of the criteria for finding the optimal parameters of a farm is its material consumption.

Pre-Revolutionary Trends of Industrial Architecture: Moscow Power Plants

The article explores the evolution of the architectural style and artistic and aesthetic features of the first Moscow power plants (Georgievskaya (1888), Raushskaya (1897) and Tramvainaya (1907)) during the period of active industrial development at the turn of the 19th and 20th centuries. The article aims to identify trends in the pre-revolutionary industrial architecture of Moscow, as well as to supplement the history of architecture with new information about the architecture of power plants.The main advantage of the article is a comprehensive art history research of the power plants’ architecture, undertaken for the first time. The author compares the Russian practice with the design experience in Europe and the USA and examines the issues of historical modernizations and modern reconstructions of objects. There are applied the methods of comparative and typological analysis, as well as the art criticism method of stylistic analysis. The article establishes that there was a gradual transition from the “brick” style to the functional design method in industrial architecture: new buildings were characterized by a reduction in decor, the use of metal trusses, an increase in the area of glazing and its use as an expressive component. The results of the research show that, by the example of the first Russian power plants’ architecture, it is possible to trace the formation of industrial practices in the country and analyze the prerequisites of the GOELRO Plan, subsequently developed by the avant-garde architects. Nowadays, the power plants, being significant architectural monuments, remain an important part of the urban infrastructure, often acquiring a new format of life after revitalization: Raushskaya is the oldest operating plant in Russia, and Georgievskaya and Tramvainaya continue their existence as cultural spaces. The study of the heritage of industrial architecture helps to determine the historical and cultural value of the buildings around us, which is necessary for their preservation.

A Multi-Scale Study on Deformation and Failure Process of Metallic Structures in Extreme Environment.

It is a macro-micro model study for defect initiation, growth and crack propagation of metallic truss structure under high engine temperature and pressure conditions during the reentry atmosphere. Till now, the multi-scale simulation methods for these processes are still unclear. We explore the deformation and failure processes from macroscale to nanoscale using the Gas-Kinetic Unified Algorithm (GKUA) and all-atomic, molecular dynamic (MD) simulation method. The behaviors of the dislocations, defect evolution and crack propagation until failure for Aluminum-Magnesium (Al-Mg) alloy are considered with the different temperature background and strain fields. The results of distributions of temperature and strain field in the aerodynamic environment obtained by molecular dynamics simulations are in good agreement with those obtained from the macroscopic Boltzmann method. Compared to the tensile loading, the alloy structure is more sensitive to compression loading. The polycrystalline Al-Mg alloy has higher yield strength with a larger grain size. It is due to the translation of plastic deformation mode from grain boundary (GB) sliding to dislocation slip and the accumulation of dislocation line. Our findings have paved a new way to analyze and predict the metallic structural failure by micro-scale analysis under the aerodynamic thermal extreme environment of the reentry spacecraft on service expiration.

Конечно-элементное моделирование состояния металлических конструкций каркасного здания

For the considered groups of structures - metal trusses, beams, columns, landings and marches of a multi-storey frame building, a continuous visual and detailed instrumental examination was performed. For load-bearing structures, verification calculations of their bearing capacity were performed. Based on a comparison of the defects identified during the inspection and the results of verification calculations, an assessment of the technical condition was made for individual structures, for each group of structural elements, as well as for the building as a whole. For structures with defects and damage, recommendations are given for their restoration and repair. Additional damages and defects were recorded, the appearance of which is associated at the object under study due to a forced break in the production of construction work. The results of surveys and calculations showed that the technical condition of landings and marches can be considered generally efficient. The results of the verification calculation showed that the technical condition of the metal columns as a whole can be considered efficient. The results of the verification calculation on the computer of metal truss structures are presented in the form of a mosaic and diagrams of internal forces. When performing verification calculations, the finite element method was applied.

Numerical analysis of deformation and failure mechanism of metal truss structure of spacecraft under re-entry aerothermodynamic environment

A coupled aerodynamic-thermoelastic analysis framework is presented to simulate the deformation and failure mechanism of metal truss structure for spacecraft under re-entry aerothermodynamic environment. The three-dimensional dynamic thermo-mechanical coupling finite element algorithm is developed by computable modeling of thermoelasticity and heat conduction equations to solve the thermo-mechanical coupling response of spacecraft structure. The aerodynamic boundary conditions such as temperature, heat flux and pressure distribution are computed and provided by the gas-kinetic unified algorithm (GKUA) based on the Boltzmann model equation. The linear interpolation method is designed and employed to couple the boundary conditions between the external aerodynamic flow field and the solid structure interface. The present thermo-mechanical coupling algorithm is verified on one-dimensional and two-dimensional transient heat flow problems with analytical solutions, and good consistency is achieved. The reliability of the GKUA for solving the boundary conditions of the external flow field and the dynamic thermo-mechanical coupling algorithm for the thermal response behavior of the internal structure material is verified by the consistency calculation of the internal and external temperature distribution. Then, the aerodynamic-thermoelastic analysis framework is further applied to study the deformation behavior of structural thermo-mechanical responses and failure mechanism of a hollow sphere under re-entry aerothermodynamic environment with emphasis placed on the influence of flight speeds, rarefied effects, algorithm schemes and damping effects. The numerical results obtained by the presented algorithm including the internal temperature, thermal stress and deformation distribution law are compared and analyzed. Finally, the deformation and failure mechanism of spacecraft structure during re-entry process are solved and analyzed by the present algorithm framework. The displacement, temperature and stress distribution contours of the structure are presented to make a preliminary understanding and evaluation on the process of spacecraft deformation and failure disintegration. It is indicated that the present coupled aerodynamic-thermoelastic analysis framework can provide a reliable, applicable and efficient platform for the thermo-mechanical coupling responses and failure mechanism of re-entry spacecraft in the end of life.

Study on Improved CG Algorithm for Reradiation Interference Calculation of Transmission Steel Tower

With the development of extra-high voltage and ultra-high voltage transmission line in China, the reradiation interference generated by induced current on the surface of transmission steel tower becomes more serious to the radio station in the vicinity. In this paper, the calculation method for reradiation interference of transmission steel tower based on method of moment is analyzed. And in order to reduce the impedance matrix storage data in the memory space and the number of iterations in the calculation, the preprocessing of matrix sparse and diagonal norm precondition is presented to improve the performance of the conjugate gradient algorithm for the reradiation interference calculation. The reradiation interference of a standard 500 kV transmission steel tower is calculated using the improved conjugate gradient algorithm. And the results show that the algorithm enhances the convergence and stability after preprocessing and is suitable to calculate the reradiation interference of super-large metal truss structure target.

Актуальність прогнозування забруднення повітря робочої зони під час виконання демонтажних робіт об’єкта «Укриття»

The characteristics of the modern radiation situation in the areas of work under the project “Reconstruction of the Shelter object of the SSE ChNPP in the part of the dismantling of the metal truss of the southern roof reinforcement” are provided. It is shown that during the period of research and industrial operation of the “New Safe Confinement — Shelter object” (NSC-SO) complex, as a result of the sealing of its containment circuit, there was a deterioration of the radiation situation due to an increase in the amount of general and non-fixed surface pollution. The reason for this is the deposition of radioactive aerosols, which are generated both in the Shelter object and during construction work in the internal volume of the NSC-SO complex. According to research data, the average value of the total density of surface pollution by beta-active nuclides of metal structures in the areas of work under the project, for the period from 2018 to 2021, increased by 9.3 times, and the value of unfixed surface pollution by 5.7 times. Such extremely unfavorable radiation conditions encourage the widest possible use of unmanned technologies with the use of remotely controlled robot manipulators (RCRM). In the case of the impossibility of using RCRM for radiation-hazardous technological operations and their replacement by operations performed manually, it is absolutely necessary to forecast the dynamics of air pollution in the working area during the performance of such works in order to guarantee the effective application of appropriate measures for personnel radiation safety. A predictive assessment of radioactive air pollution of work zones in the internal volume of the NSC-SO complex during the execution of project work was provided, which made it possible to optimize measures for the radiation safety of working personnel, in particular, in the selection of appropriate types of means of individual protection of respiratory organs. The proposed approach can be used during the planning of further radiation-hazardous works in the internal volume of the NSC-SO complex, namely, during the dismantling of unstable structures of the Shelter object and the partial removal of nuclear materials and high-level waste from the Shelter object.

Effective roof design for the universal gym

The article presents the optimal design of a metal truss designed to cover the roof of a universal gym of size 12x24 m. Trusses made of sloping welded profiles have been shown to be more efficient than traditional double-angle trusses currently used in industrial building roofing. As an example, 24 m arched farms were designed and working drawings were developed.

Специфическое конструктивное решение для покрытия больших площадей пространственной металлической фермой

. The relevance of the research results given in the article lies in the need to apply new constructive solutions for large spaces. The purpose of this work is to search for new design solutions for covering large areas with spatial metal trusses. The problems of forming a computational spatial bar finite element model of a steel spatial truss of a dome-shaped radial-ring structure were solved. The calculation of the spatial system was carried out using the finite element method of current computer programs, new constructive solutions for spatial metal trusses were adopted. The stress-strain states of the model from a given load have been determined. The calculation of the spatial system was carried out using the finite element method of current computer programs, new constructive solutions for spatial metal trusses were adopted. The research results can be used in the formation of architectural and structural solutions of a building using a new structural arrangement of the elements of a spatial truss.

Interfacial failure of circular or tubular hybrid bonded joints: A theoretical description

In different industries, the bonding technique has gained several advances in recent years. However, due to the specificity of each industry, the bonded joints may present different configurations. For instance, in the case of metallic truss bridges, the use of Carbon Fibre Reinforced Polymers (CFRP) bonded on the steel surface members may require circular or even tubular transitions between these materials. Although the bonded transitions between a metal and a composite material have been deeply studied with flat surfaces the information on circular or tubular hybrid bonded joints is still scarce. Therefore, the present study aims to mitigate some of this lack of knowledge by proposing an analytical solution able to describe the interfacial debonding process between a circular or tubular bonded transition between two materials. The proposed model also aims to simulate the interfacial debonding of double butt (or stepped) lap joints. Under these circumstances, a bilinear local adhesive model is adopted which required the quantification of the elastic and the softened stiffnesses as well as the pure Mode II fracture energy. The Finite Element Method (FEM) is used for the validation of the proposed model. The behaviour of the adhesive joint between materials is numerically modelled through the Cohesive Zone Modelling (CZM) in which the same bilinear shape used in the analytical solutions is adopted. Different situations were analyzed thoroughly and the numerical simulations tracked very closely the analytical results obtained from the proposed closed-form solutions.

Variant design of farms using the LIRA-CAD program

This article is devoted to the study of the economic efficiency of using trusses of various outlines and sectional shapes. Today, metal trusses in large-span construction have practically no alternative due to fast production, installation, and most importantly, the quality characteristics they possess. This is an excellent ratio of the mass of the frame and its design load, durability, ease of installation and assembly, resistance to external influences. In practice, because of variant design, a constructive solution is determined that provides a minimum of costs for the acquisition of material, fabrication of the structure and installation. Within the framework of this work, it was determined and recommended when designing to use the obtained most economical constructive solution.

Investigation of fire resistance of steel structures covering a warehouse building under different temperature conditions

Introduction . In the process of designing warehouse buildings, taking into account the adopted design decisions, it is required to assess the compliance of the actual fire resistance limits of building structures with the required fire resistance limits. The fire resistance limits of the (actual) building structures are determined under the influence of a “standard” temperature regime, the use of which can lead to both laying an overestimated fire resistance margin in a project and underestimating the thermal effect in a “real” fire. Aims and purposes . The purpose of the study is to assess the convergence of the “standard” temperature regime and possible “real” temperature regimes of fires in modern warehouse buildings, as well as the correspondence of actual fire resistance limits to the effects of “real” fires. To achieve this goal, the following tasks were solved: mathematical modeling of the development of a “real” fire by the field method in a warehouse building at different fire loads was carried out, as well as modeling of heating of the supporting structures of the coating according to the standard temperature regime and the “real” temperature conditions of the fire obtained during the simulation; the required fire resistance limits of the bearing building structures of the coating are determined through the equivalent duration of the fire. Methods . A storage building of a standard form with dimensions of 12×12×6.5 m was chosen as the object of the study. The building has a 4×4 meter gate in the amount of 2 pieces and an entrance door of 1×2 meter size. Within the walls of the building are 32 windows measuring 0.7×1 meter. Coverage — an impassable flat roof over metal trusses. The parameters of the fire load during mathematical modeling were taken according to the reference data of Yu.A. Koshmarov 12 types of typical fire load stored in warehouse buildings are considered. For mathematical modeling of “real” temperature fires, the “Fire Dynamics Simulator” (FDS) software package was used, which implements a field (differential) mathematical model. For mathematical modeling of the heating process of steel building structures, the finite-difference method for solving the Fourier heat equation with external and internal nonlinearity was used, implemented in the ANSYS Mechanical software package. results and discussion. The results of modeling in the FDS software package show that the temperature impact on the structure according to the standard temperature regime for fire loads: cables+wires, industrial oil, ethyl alcohol was less, which indicates an underestimation of the thermal impact on the structure. The results of modeling the heating of structures showed that the heating time of the coating truss is up to 400–700 °C for fire loads: cables+wires, industrial oil, ethyl alcohol less than the time obtained from standard tests, which indicates an initial underestimation of the actual fire resistance of steel structures of the coating when designing warehouse buildings. Conclusions . The assumption that the thermal impact of the standard temperature regime on the steel structures of modern warehouse complexes was underestimated was confirmed for 3 of the 12 fire loads considered, namely: cables+wires, industrial oil, ethyl alcohol.

Strength and deformability of lightweight metal trusses with elements from cut I-beams

The article is devoted to the study of the strength and deformability of light metal trusses with elements made of cut I-beams based on experimental tests. A truss design is proposed based on the idea of a waste – free technology for obtaining the maximum number of truss elements in the process of cutting the initial billet-a rolling I-beam. The manufacturing technology of the farm, research tasks and test samples are described. The developed and manufactured designs of truss models were a geometric similarity of trusses with parallel belts with a span of 24 m, a cross – section height along the shelves of the belts-2.4 m, with the length of the belt panels equal to 3 m, calculated for different loads. The analysis of the obtained results showed that the theoretical values of axial stresses in the elements of truss models differ from the values of experimental axial stresses in General by no more than 8%. According to the results of numerical studies of the stress-strain state of trusses in the elastic stage of their operation, it was established: - truss structures have sufficient stiffness and strength (the coefficient of load-bearing capacity was a value that varies for trusses of various series within the range of 1.34 – 1.7); - the stress values in the truss elements calculated during the processing of the results of numerical studies have a large similarity with the stress values calculated on the basis of experimental data.

ОПТИМИЗАЦИЯ НАГРУЖЕНИЯ МЕТАЛЛИЧЕСКИХ ФЕРМ

Loading optimization of the metal trusses has a variational basis. The universal criterion of optimization is the minimum of potential energy of the system (additional energy) in functional space expanded at the expense of functions fields of configuration and (or) material modules, and load. Under the condition of homogeneous linear elastic material optimal truss represents as quasiuniresistant virtual system with internal forces Ni/ⱷi (ⱷi – decrease coefficient of designed metal resistance of to tension and compression. The value ∑Nili (l is pivot length) is in general case the characteristic of the degree of a priori stability of truss, in special case (the load at the line, connecting supports) determines optimal variant of loading. As numerical experiment was consider the distribution of load ∑Fi=const for the truss with descending (ascending) pivot. It is established the independence of optimal loading variant from truss grating structure.

Reconstruction of Bearing Roof Trusses an Industrial Building without Interrupting the Production Process

The main stages of the reconstruction of the supporting metal truss at the operating industrial enterprise are considered. Reconstruction is due to the need of changing the process. An original solution was proposed to change the design scheme of the truss due to the rearrangement of the lower belt. Main features of this reconstruction are the difficulties caused by limited working space and the implementation of all types of work without stopping the process. The stress-strain state of the farm is investigated at various stages of work: the actual state at the time of the technical survey, during the work period and after all types of reconstruction work have been completed. The article provides technological solutions for the preparation of the working platform, the organization of assemblies, and the installation of structures. Each stage of the reconstruction was controlled by performing various types of calibration calculations. The distribution of internal efforts in the elements of the farm is shown before and after its installation in the working position. Additionally, the behavior of the design of the farm on various possible operational impacts is investigated.

First building engineers in architectural practice of St. Petersburg at the beginning of the 19th century

The emergence of the specialty of civil engineer in the first half of the 19th century had a significant impact on architectural practice in St. Petersburg. The differentiation of the professions of engineer and architect took place for the first time; both specialists began to participate in the design. The appearance of such engineers as Augustine Betancourt, Matvey Clark, Pierre-Dominique Bazin and Wilhelm von Tretter brought about changes in all areas of architecture and construction. New building structures and materials appeared, as well as methods for checking and calculating. Designing has become comprehensive, the activities of the Committee for Structures and Hydraulic Works led by Betancourt covered urban development, individual buildings and all types of utilities. The formation of engineering education took place, which brought up the next generation of Russian engineers.The article considers the most important aspects of the activities of Augustine Betancourt, who laid the foundations for engineering education in Russia; Matvey Clark, who created the first metal beams and trusses; Pierre Dominique Bazin, who continued the development of engineering education, as well as Wilhelm von Tretter, one of the founders of iron bridge construction in Russia.