Publikační činnost Katedry konstrukcí / Publications of Department of Building Structures (221)

Permanent URI for this collectionhttp://hdl.handle.net/10084/64806

Kolekce obsahuje bibliografické záznamy publikační činnosti (článků) akademických pracovníků Katedry konstrukcí (221) v časopisech registrovaných ve Web of Science od roku 2003 po současnost.
Do kolekce jsou zařazeny:
a) publikace, u nichž je v originálních dokumentech jako působiště autora (adresa) uvedena Vysoká škola báňská-Technická univerzita Ostrava (VŠB-TUO),
b) publikace, u nichž v originálních dokumentech není v adrese VŠB-TUO uvedena, ale autoři prokazatelně v době jejich zpracování a uveřejnění působili na VŠB-TUO.

Bibliografické záznamy byly původně vytvořeny v kolekci Publikační činnost akademických pracovníků VŠB-TUO, která sleduje publikování akademických pracovníků od roku 1990.

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Now showing 1 - 20 out of 90 results

Experimental measurement of the load-bearing capacity of wire hooks and bends used in gabion retaining walls
(The Geomate International Society, 2023) Čajka, Radim; Burkovič, Kamil; Neuwirthová, Zdeňka; Mynarčík, Petr; Bujdoš, David
Gabion walls are today a very popular and ecological solution for retaining walls in civil engineering. Gabions are made of stones placed in wire baskets made of galvanized wire, which are interconnected by hooks and bends. Their advantage is the natural appearance, good conditions for landscaping and catching climbing plants. Unlike concrete or masonry retaining walls, they cannot have cracks and therefore resist uneven subsidence of the subsoil. However, the decisive factor for their load-bearing capacity is the quality of the quarry stone, its placement and the load-bearing capacity of the individual wires and, above all, their joints. In the laboratories of the Faculty of Civil Engineering of the Technical University of Ostrava, a number of tests of wire basket hook joints were performed, which were taken from damaged gabions on construction sites. The results of these tests will enable better prediction of the static effect of gabion walls in their design and implementation in construction practice. The paper presents the results of these tests and recommendations for their design and planning.
Industrial floor faults caused by volume changes in concrete and subsoil: case study
(Polska akademia nauk. Komitet, Inżynierii Lądowej i Wodnej. Politechnika Warszawska, Wydział Inżynierii Lądowej, 2023) Čajka, Radim; Vašková, Jana; Šmiřáková, Martina; Burkovič, Kamil; Neuwirthová, Zdeňka
Large floors of industrial enterprises, warehouses, stores, and shopping centres are quite heavily loaded with production technologies, transport mechanisms, stored material or shelf stackers. Regarding simple reinforcement and construction, industrial floors have been used in recent decades mainly reinforced with fibres from so-called fibre-reinforced concrete. Most slab failures are caused by extreme loads on the unbearable subsoil, a small amount of fibres, or by the shrinkage of concrete due to insufficient structural design of sliding, shrinking and expansion joints. Recently, however, in several constructions, structural failures have occurred caused by a volume-unstable subsoil in the form of a mixture of slag or metallurgical debris. The article deals with some failures of fibre concrete floors in practice, their methods of diagnostics and laboratory analysis of samples. The results are supplemented by practical examples of floor failures with respect to their origin.
Stiffness and deformation analysis of cross-laminated timber (CLT) panels made of Nordic spruce based on experimental testing, analytical calculation and numerical modeling
(MDPI, 2023) Dobeš, Pavel; Lokaj, Antonín; Vavrušová, Kristýna
Timber structures are currently more important for solving tasks in construction practice. For this reason, there is an opportunity for research in the area of physical tests and numerical models. This paper deals with the determination and comparison of the deformation properties of cross-laminated timber (CLT) panels based on laboratory tests, analytical calculation and numer ical modeling. CLT panels are structural building components consisting of cross-oriented solid timber layers. Three types of panels with different geometry and number of layers (three, five and seven) were experimentally tested using a four-point bending test, where load–deformation curves were recorded. The results of the experimental testing of the three-layer panels were subsequently compared with a numerical model in SCIA Engineer, a numerical model in ANSYS Workbench and an analytical calculation. The research shows a good agreement in bending behavior between the laboratory tests, the analytical calculation according to the standard and two different approaches in numerical analysis.
Experimental measurement of deposition chloride ions in the vicinity of road cut
(MDPI, 2023) Vacek, Miroslav; Křivý, Vít; Kreislová, Kateřina; Vlachová, Markéta; Kubzová, Monika
Chloride ions are nowadays the main cause of the degradation of steel and reinforce concrete construction in the vicinity of the road. On the other hand, chloride ions, usually in the form of de-icing salts or brine, are very important for safe winter traffic on the roads. This creates a slightly schizophrenic situation where it is necessary to ensure safe traffic in the winter period and at the same time to affect the service life of the structure as little as possible. The effect of the roadway on chloride deposition is a long-studied, but still imprecisely understood, part of the effect of chloride ions on structures in the vicinity of the roadway. This paper discusses the experimental measurement of chloride deposition in the vicinity of the I/11 road in the Czech Republic by dry plate method, wet candle method and corrosion coupons. Statistical analysis of correlation and regression is performed on the results of measurements by wet candle and horizontal dry plate methods. The methods are interdependent. A detailed analysis of the surface and chemical properties of the corrosion products is performed on the corrosion coupons. Using the corrosion loss, the environmental category C2 is determined. Observation of the microclimate in the vicinity of the roads gives to engineers a basis for the correct design of structures around the roads. The conclusions of the experimental measurements are intended to help engineers to design a structure that is safe, serviceable and sufficiently resistant to chloride ions within its service life.
Fresh and hardened properties of high-performance fiber-reinforced concrete containing fly ash and rice husk ash: Influence of fiber type and content
(Springer Nature, 2022) Ho, Nguyen-Trong; Dang, Viet Quoc; Nguyen, Minh-Hieu; Hwang, Chao-Lung; Huynh, Trong-Phuoc
Although fibers are used only infrequently as an additive in concrete in the construction industry, fiber-enhanced concrete is known to provide a wide range of advantages over conventional concrete. The main objective of this study was to investigate the influences of fiber type and content on the mechanical properties and durability of high-performance fiber-reinforced concrete (HPFRC) designed using a novel densified mixture design algorithm with fly ash and rice husk ash. Three types of fiber, including polypropylene (PP) fiber, steel fiber (SF), and hybrid fiber (HF), were considered. Based on the results, the inclusion of fibers decreased HPFRC flowability, regardless of fiber type. Although the compressive strength of HPFRC with 1.6% PP fiber content was 11.2% below that of the reference HPFRC specimen at 91 d of curing age, the 91-d compressive strengths of both SF and HF-enhanced HPFRC specimens were significantly better than that of the reference HPFRC specimen. Furthermore, the HPFRC specimens incorporating SF and HF both exhibited better splitting tensile and flexural strengths as well as less drying shrinkage than the HPFRC specimens incorporating PP fiber. However, the fiber-enhanced specimens, especially those with added SF, registered less surface electrical resistivity and greater vulnerability to chloride ion penetration than the reference HPFRC specimen.
Numerical and experimental analysis of the load-carrying capacity of a timber semi-rigid dowel-type connection
(MDPI, 2022) Johanides, Marek; Lokaj, Antonín; Dobeš, Pavel; Mikolášek, David
The paper deals with the analysis of the load-carrying capacity of a timber semi-rigid connection created from a system of two stands and a rung. The connection was made from glued laminated timber with metal mechanical dowel-type fasteners. Not only a common combination of bolts and dowels, but also fully threaded screws were used for the connection. The aim of the research and its motivation was to replace these commonly used fasteners with more modern ones, to shorten and simplify the assembly time, and to improve the load-carrying capacity of this type of connection. Each of these two types of connections was loaded statically, with a slow increase in force until failure. The paper presents results of the experimental testing. Three specimens were made and tested for each type of the connection. Experimental results were subsequently compared with numerical models. The achieved results were also compared with the assumption according to the currently valid standard. The results indicate that a connection using fully threaded screws provides a better load-carrying capacity.
Study of effect of reference time of chloride diffusion coefficient in numerical modelling of durability of concrete
(MDPI, 2022) Lehner, Petr; Koubová, Lenka; Rosmanit, Miroslav
The results of numerical calculations on the resistance of the reinforced concrete bridge deck to chlorides are compared with a different approach to the diffusion coefficient of the input parameter, and presented. The aim is to point out the necessity of a correct model adjustment in the case of using diffusion parameters obtained differently at different measurement times. The diffusion parameter, as a typical concrete material constant, was derived from electrical resistivity measurements and using the least-squares method from a direct chloride test. Due to the different times of obtaining the concrete parameters, a control calculation was performed, which showed that the numerical model for calculating the initiation of reinforcement corrosion in chloride-exposed reinforced concrete requires the application of not only a suitable diffusion parameter but also an adequate reference time. The article points out the need to use an adequate reference time introduced in the numerical calculation of the durability of reinforced concrete with respect to aggressive substances. The results show that the most appropriate reference time value is derived from the average measurement time related to the lifetime of the concrete.
Microstructure, shrinkage, and mechanical properties of concrete with fibers and experiments of reinforced concrete beams without shear reinforcement
(MDPI, 2022) Sucharda, Oldřich; Marcalíková, Zuzana; Gandel, Radoslav
The current findings on concrete with fibers show that research has focused primarily on individual aspects, especially in terms of mechanical properties and structural uses. However, no broader view of the problems solved has been provided. In this study, we present a conceptual overview of a new, comprehensive experimental program for the assessment of fiber-reinforced concrete, which includes the analysis of microstructural and structural elements, as well as specific features such as shrinkage and resistance to pressurized water. The proposed experimental program included several variants of schemes for the dosing of fibers into concrete, using steel fibers that were short and straight. Fiber dosing was performed up to 110 kg/m(3). The basic tests performed included tests of the compressive strength of concrete, and of the split and flexural tensile strength for different dosing amounts. Within the structural tests of reinforced concrete beams without shear reinforcement, two variants of spans with different degrees of reinforcement were implemented. Herein, the test results are evaluated graphically with a detailed analysis of the positive effect of fibers, and we also provide general recommendations for the structural uses of the fibers used and the design of fiber-reinforced concrete structures. Among the important results of this experimental program was the observation of a significant increase (of the order of tens) of the percentage of the split tensile strength and an increase of the overall load-bearing capacity of the reinforced concrete beams without shear reinforcement. Among the important aspects of our findings is the fact that a fine-grained concrete mixture was used, which increased resistance to pressure water seepage, and therefore, the effect of shrinkage can be influenced by the method of production and the treatment of the concrete used. We also provide detailed figures of the microstructure.
Numerical and experimental analysis of the rotational stiffness of a timber semi-rigid dowel-type connection
(MDPI, 2022) Johanides, Marek; Lokaj, Antonín; Dobeš, Pavel; Mikolášek, David
The paper deals with the analysis of the rotational stiffness of a semirigid connection created from a system of two stands and a rung. The connection was made from glued laminated timber with metal mechanical dowel-type fasteners. Not only a common combination of bolts and dowels but also fully threaded screws were used for the connection. The aim of the research and its motivation was to replace commonly used fasteners with more modern ones, to shorten and simplify the assembly time, and to improve the load-carrying capacity of this type of connection. Each of these two types of connection was loaded to the level of 60%, 80%, and 100% of the ultimate limit state value. Subsequently, the rotational stiffness was determined for each load level after five loading and unloading cycles. This paper presents the results and comparison of the experimental testing and the numerical modeling. The obtained results were also compared with the assumption according to the currently valid standard.
Timber semirigid frame connection with improved deformation capacity and ductility
(MDPI, 2022) Johanides, Marek; Lokaj, Antonín; Mikolášek, David; Mynarčík, Petr; Dobeš, Pavel; Sucharda, Oldřich
The present study deals with the innovation and the possibilities of improving the design solution of a frame connection for two selected types of fasteners. All specimens were made of glued laminated timber. Dowel-type mechanical fasteners, a combination of bolts and dowels, and full-threaded screws were used for the connection. The main goal of this research was to replace the typical solution (common dowel-type fasteners) with a more modern, faster, and easier solution in order to improve the load-carrying capacity, ductility, and deformation capacity of this type of frame connection. This article also aimed to provide a detailed evaluation of the mechanical properties of the used glued laminated timber and fasteners in order to comprehensively evaluate the research task. For the design solution, a frame connection created from a system of two struts and a partition was chosen as the basis of the experimental program. Dowel-type mechanical fasteners, as well as combinations of bolts and dowels, were used for the connection; however, in addition to these standardly used mechanical fasteners, full-threaded screws were used. The article describes the use of static destructive testing to determine the ductility of the connection, considering different variations in the strengthening of the individual segments of the mentioned connection means. In the first variation, the individual components of the frame were not reinforced in any way. In the second, the crossbar was reinforced with two full-threaded bolts. In the third, the webs and the crossbar were reinforced with two full-threaded bolts. In the article, these ductility values were compared with each other and the procedure was set by the currently valid standard.
Corrosion damage to joints of lattice towers designed from weathering steels
(MDPI, 2022) Křivý, Vít; Vašek, Zdeněk; Vacek, Miroslav; Mynarzová, Lucie
The article dealt with the load-bearing capacity and durability of power line lattice towers designed from weathering steel. Attention was paid in particular to the bolted lap joints. The article evaluates the static and corrosion performance of bolted lap joints in long-term operating towers, and also presents and evaluates design measures that can be applied in the design of new lattice towers, or in the reconstruction of already operating structures. Power line lattice towers are the most extensive realization of weathering steel in the Czech Republic. On the basis of the inspections carried out to evaluate the working life of the transmission towers in operation, it can be stated that a sufficiently protective layer of corrosion products generally developed on the bearing elements of the transmission towers. However, the development of crevice corrosion at the bolted joints of the leg members is a significant problem. In this paper, the corrosion damage of bolted joints was evaluated considering two basic aspects: (1) the influence of crevice corrosion on the bearing capacity of the bolted joint was evaluated, using experimental testing and based on analytical and numerical calculations; (2) appropriate design measures applicable to the rehabilitation of developed crevice corrosion of in-service structures, or the elimination of crevice corrosion in newly designed lattice towers, was evaluated. Calculation analyses and destructive tests of bolted joints show that the development of corrosion products in the crevice does not have a significant effect on the bearing capacity of the joint, provided that there is no significant corrosion weakening of the structural elements, and bolts of class 8.8 or 10.9 are used. The results of the long-term experimental programme, and the experience from the rehabilitations carried out, show that, thanks to appropriate structural measures, specified in detail in the paper, the long-term reliable behaviour of the lattice towers structures is ensured.
Numerical modeling and diagnostic of FRC slab under centric and eccentric load
(Sciendo, 2022) Marcalíková, Zuzana; Čajka, Radim
The solved area of research is the slab in interaction with the subsoil, where the goal is numerical modeling of the problem using a 3D computational model and nonlinear analysis. Specifically, the case of two experiments with a slab with centric and eccentric loading is solved. The performed experiments are used after for numerical modelling when a comprehensive set of laboratory tests of mechanical properties of fiber-reinforced concrete is also performed. Specifically, compressive strength, modulus of elasticity, splitting tensile test and bending tensile test were performed. The performed experiments are evaluated using 2D sections and 3D approximation surfaces, which are then used for load-displacement diagrams. Numerical modeling is based on nonlinear analysis and the use of the finite element method. The computational model use isoparametric finite elements. Based on the performed experiments and numerical modeling, the evaluation of the solved task is performed.
Load-carrying capacity of double-shear bolted connections with slotted-in steel plates in squared and round timber based on the experimental testing, European yield model, and linear elastic fracture mechanics
(MDPI, 2022) Dobeš, Pavel; Lokaj, Antonín; Mikolášek, David
Nowadays, the use of timber as a building material is gaining more prominence. When designing timber structures, it is necessary to pay increased attention to the design of their connections. The commonly used connections are dowel-type connections, which are often used in combination with steel plates slotted into cut-outs in timber members. The presented paper deals with the behavior of double-shear bolted connections of squared timber and round timber with slotted-in steel plates. Several variants of connections with different distances between the fastener and the loaded end were selected for the experimental testing. A total of six types of test specimens were made from spruce timber, for which their selected physical properties were determined and evaluated before the experimental testing. Test specimens of bolted connections were first tested in tension parallel to the grain until failure under quasi-static loading. The connections were broken by splitting. Ductile failure preceded brittle failure. The actual load-carrying capacities were lowest for the lowest end distance. The load-carrying capacities for the middle and the longest end distances were comparable. The results of the experiments were then used for comparison with calculation procedures according to the standard for the design of timber structures and with calculations according to the theory of linear elastic fracture mechanics. The experiments and the analytical models were supported by a simple numerical analysis based on the finite element method.
Determination of construction process duration based on labor productivity estimation: A case study
(Sciendo, 2021) Kubečková, Darja; Smugala, Stanislav
Monitoring labor productivity and how to decrease construction costs are the key issues in the planning process of a construction project. The CONTEC automated system combined with statistical methods assists in predicting the amount of time required to complete construction works according to the specified number of deployed work crews, technological processes, and labor required for certain production in person-hours. This study applies statistical analyses and probability theories for plastering work, which represents a labor-intensive construction process. The goal of the research is to determine the probability of completion of the construction process based on monitoring the mean value of performance. By application of statistical analyses a decrease in the performance standard has been proved compared with the planned values given in the CONTEC database. The decrease in performance, which was also caused by the number of days with unfavorable climatic conditions and demonstrated by performing interval estimates based on the collection of statistical data, was later confirmed by a relative frequency test. The measures taken were in terms of establishing the required number of personnel capacities for complying with the construction schedule.
Prediction of ultralow cycle fatigue damage of thin-walled steel bridge piers
(Hong Kong Institute of Steel Construction, 2021) Tang, Zhan-Zhan; Xue, Han-Yang; Liu, Hong; Zhang, Wei
Ultralow cycle fatigue (ULCF) failure was first observed on steel bridge piers in the Kobe earthquake, and the ultimate strength and ductility evaluation formulas of thin-walled steel bridge piers were established. In this study, parametric analysis of steel piers was carried out to study the influence of the structural parameters on the ULCF damage evolution. The evolution of the ULCF damage of the base metal, the deposited metal, and the heat-affected zones was studied based on two types of steel piers with hollow box and pipe sections. Then, practical formulas to predict the ULCF damage level of steel piers under cyclic loading were proposed. Finally, the proposed formulas were validated by comparisons with the experimental results. The results show that the heat-affected zone is more vulnerable to ULCF failure than the base metal and the deposited metal. Moreover, the practical formulas to predict the ULCF damage index of the steel piers under cyclic loading were proposed, and the formulas effectively predicted the ULCF crack of the steel piers.
Shear lag analysis due to flexure of prismatic beams with arbitrary cross-sections by FEM
(Budapesti Muszaki es Gazdasagtudomanyi Egyetem, 2021) Tran, Dang-Bao; Navrátil, Jaroslav
This paper presents the use of a finite element method (FEM) to analyze the shear lag effect due to the flexure of beams with an arbitrary cross-section and homogeneous elastic material. Beams are constrained by the most common types of supports, such as fixed, pinned, and roller. The transverse, concentrated, or distributed loads act on the beams through the shear center of the cross-section. The presented FEM transforms the 3D analysis of the shear lag phenomenon into separated 2D cross-sectional and 1D beam modeling. The characteristics of the cross-section are firstly derived from 2D FEM, which uses a 9-node isoparametric element. Then, a 1D FEM, which uses a linear isoparametric element, is developed to compute the deflection, rotation angle, bending warping parameter, and stress resultants. Finally, the stress field is obtained from the local analysis on the 2D-cross section. A MATLAB program is executed to validate the numerical method. The validation examples have proven the efficiency and reliability of the numerical method for analyzing shear lag flexure, which is a common problem in structural design.
Analysis of fiber-reinforced concrete slabs under centric and eccentric load
(MDPI, 2021) Marcalíková, Zuzana; Bílek, Vlastimil; Sucharda, Oldřich; Čajka, Radim
Research on the interaction between slabs and subsoil involves the field of materials engineering, concrete structures, and geotechnics. In the vast majority of cases, research focuses on only one of these areas, whereas for advanced study and computer simulations, detailed knowledge of the whole task is required. Among the new knowledge and information upon which this article focuses is the evaluation of subsoil stress using specialized pressure cells, along with detailed measurements of the deformation of a fiber-reinforced concrete slab. From a design point of view, this research is focused on the issue of the center of the cross section and the influence of eccentricity. Knowledge in this area is not yet comprehensively available for fiber-reinforced concrete slabs, where 2D deformation sections of the slab and 3D deformation surfaces of the slab are used in experiments. The experimental program includes a centrically and eccentrically loaded slab. These are structural elements that were tested on a specialized device. Both slabs had the same concrete recipe, with a dispersed reinforcement content of 25 kg/m(3). The dimensions of the slab were 2000 x 2000 x 150 mm. Laboratory tests assessed compressive strength, the modulus of elasticity, splitting tensile strength, and bending tensile strength. Based on approximate data from the 3D deformation surfaces, an evaluation of the load-displacement diagrams for the center of the slab and for the center of eccentricity was performed. In conclusion, an overall evaluation and discussion of the results relies on experiments and the mechanical properties of fiber-reinforced concrete.
Rotational stiffness and carrying capacity of timber frame corners with dowel type connections
(MDPI, 2021) Johanides, Marek; Mikolášek, David; Lokaj, Antonín; Mynarčík, Petr; Marcalíková, Zuzana; Sucharda, Oldřich
With the development of wooden structures and buildings, there is a need to research physical and numerical tests of wood-based structures. The presented research is focused on construction and computational approaches for new types of joints to use in wooden structures, particularly glued lamella elements made of wood and wood-based composites. This article focuses on improving the frame connection of a wooden post and a beam with the use of fasteners to ensure better load-bearing capacity and stiffness of the structure. In common practice, bolts or a combination of bolts and pins are used for this type of connection. The aim is to replace these commonly used fasteners with modern ones, namely full thread screws. The aim is also to shorten and simplify the assembly time in order to improve the load-bearing capacity and rigidity of this type of frame connection. Two variations of the experimental test were tested in this research. The first contained bolts and pins as connecting means and the second contained the connecting means of a full threaded screw. Each experiment contained a total of two tests. For a detailed study of the problem, we used a 2D or 3D computational model that models individual components, including fasteners.
Physical tests of alternative connections of different high roof purlins regarding upward loading
(MDPI, 2021) Rosmanit, Miroslav; Pařenica, Přemysl; Sucharda, Oldřich; Lehner, Petr
Thin-walled cold-rolled sections are used in the construction industry, especially in the roofing of large-span halls. The load-bearing capacity of a thin-walled structure depends to a large extent on the load-bearing capacity of the details at the point of attachment to the structure and the interconnection of the individual thin-walled elements. Therefore, in the case of thin-walled structures, it is necessary to use additional structural elements such as local reinforcement, stabilising elements, supports, and other structural measures such as the doubling of profiles. This paper focused on the behaviour of tall Z300 and Z350 mm thin-walled trusses at the connection to the superstructure regarding upward loading (e.g., wind suction and so on). Two section thicknesses, 1.89 mm and 2.85 mm, were experimentally analysed. Furthermore, two types of connections were prepared, more precisely without and with a reinforced buckle. The experiments aimed to investigate the behaviour and load-carrying capacity of the detail of the roof truss connections to the supporting structure. The resulting load capacity values were compared with normative approaches. Analyses of the details of the bolt in the connection are also presented. The paper presents a practical evaluation of the physical test on real structural members.
Torsional shear stress with arbitrary cross-sections in homogeneous isotropic elastic material using finite element method
(ČVUT, Fakulta stavební, 2021) Tran, Dang-Bao
Determining the shear stress of a structural element caused by torsion is a vital problem. The analytical solution of the Saint-Venant torsion is only suitable for simple cross-sections. The numerical methods to evaluate the shear stress due to torsion of complicated cross-sections is indispensable. Many scientists have studied the torsion problem with various numerical methods. This paper aims to present an efficient finite element method for assessing the shear stress with arbitrary cross-sections in homogeneous isotropic elastic material due to torsion. MATLAB is the language for programming the numerical method. The validation examples were performed to show the reliability and efficiency of the author's numerical method.

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