Publikační činnost Experimentálního a diagnostického stavebního centra (207)

Permanent URI for this collectionhttp://hdl.handle.net/10084/133519

Kolekce obsahuje bibliografické záznamy publikační činnosti (článků) akademických pracovníků Experimentálního a diagnostického stavebního centra (207) v časopisech registrovaných ve Web of Science od roku 2003 po současnost. Experimentální stavební centrum vzniklo sloučením subjektů 206 a 223 v roce 2019.
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 - 14 out of 14 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.
Experimental study of high thin-walled cold-rolled Z cross-sections purlins
(Elsevier, 2023) Pařenica, Přemysl; Mynarčík, Petr; Lehner, Petr
Thin-walled cross-sections (TWCS) are used in the construction industry in many applications. The advantage of TWCS is its low weight, which is advantageous both in handling structural elements and the overall value of the structure. The presented paper is focused on the behaviour of Z high thin-walled purlins (300 and 350 mm high) at the point of connection to the supporting structure and the evaluation of whether the existing standard approach can be used to design this type of detail. A total of 60 large-scale experiments were conducted in various settings and categories. The experiments aimed to determine the bearing capacity of the connection of the roof purlins to the supporting structure. Another goal was to determine the effect of the additional reinforcement clip on the overall load-bearing capacity of the connection. Therefore, individual load assemblies were tested with and without a reinforced clip. The results obtained were compared with the analytical procedure according to the standard. Then conclusions were drawn on the applicability of existing standard approaches for the studied purlin joints. The use of analytical calculations has been found to not always be appropriate.
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.
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.
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.
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.
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.
Comparative study of high-performance concrete characteristics and loading test of pretensioned experimental beams
(MDPI, 2021) Matečková, Pavlína; Bílek, Vlastimil; Sucharda, Oldřich
High-performance concrete (HPC) is subjected to wide attention in current research. Many research tasks are focused on laboratory testing of concrete mechanical properties with specific raw materials, where a mixture is prepared in a relatively small amount in ideal conditions. The wider utilization of HPC is connected, among other things, with its utilization in the construction industry. The paper presents two variants of HPC which were developed by modification of ordinary concrete used by a precast company for pretensioned bridge beams. The presented variants were produced in industrial conditions using common raw materials. Testing and comparison of basic mechanical properties are complemented with specialized tests of the resistance to chloride penetration. Tentative expenses for normal strength concrete (NSC) and HPC are compared. The research program was accomplished with a loading test of model experimental pretensioned beams with a length of 7 m made of ordinarily used concrete and one variant of HPC. The aim of the loading test was to determine the load-deformation diagrams and verify the design code load capacity calculation method. Overall, the article summarizes the possible benefits of using HPC compared to conventional concrete.
Analysis of rotational stiffness of the timber frame connection
(MDPI, 2021) Johanides, Marek; Kubincová, Lenka; Mikolášek, David; Lokaj, Antonín; Sucharda, Oldřich; Mynarčík, Petr
Initially, timber was considered only as an easily accessible and processable material in nature; however, its excellent properties have since become better understood. During the discovery of new building materials and thanks to new technological development processes, industrial processing technologies and gradually drastically decreasing forest areas, wood has become an increasingly neglected material. Load-bearing structures are made mostly of reinforced concrete or steel elements. However, ecological changes, the obvious problems associated with environmental pollution and climate change, are drawing increasing attention to the importance of environmental awareness. These factors are attracting increased attention to wood as a building material. The increased demand for timber as a building material offers the possibility of improving its mechanical and physical properties, and so new wood-based composite materials or new joints of timber structures are being developed to ensure a better load capacity and stiffness of the structure. Therefore, this article deals with the improvement of the frame connection of the timber frame column and a diaphragm beam using mechanical fasteners. In common practice, bolts or a combination of bolts and pins are used for this type of connection. The subject 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 capacity and rigidity of this type of frame connection.
Effects of loaded end distance and moisture content on the behavior of bolted connections in squared and round timber subjected to tension parallel to the grain
(MDPI, 2020) Lokaj, Antonín; Dobeš, Pavel; Sucharda, Oldřich
This article presents the results of static tests on bolted connections in squared and round timber with inserted steel plates. The experiment evaluates structural timber connections with different distances between the fastener and the loaded end at different moisture contents. Specimens were loaded by tension parallel to the grain and load-deformation diagrams were recorded. Fifty-six specimens with three different distances between the fastener and the loaded end, at different moisture contents, were tested. The results were statistically evaluated using regression analysis, complemented with load-deformation curves, and compared with calculations according to the valid standard for design of timber structures. A decrease in the evaluated load-carrying capacity with increasing moisture content was confirmed experimentally. A slight increase in the evaluated load-carrying capacity with increasing fastener distance from the loaded end was found.
Experimental testing of masonry subjected to concentrated load in direction of bed joints
(MDPI, 2020) Kozielová, Marie; Mynarzová, Lucie; Mynarčík, Petr
One of the options for rehabilitating existing masonry buildings is a post-tensioning of masonry. The deformation properties of the masonry in the direction parallel to bed joints are essential for the design of a suitable value of the applied force. However, these values are usually not available or are defined only roughly. The aim of this study was to determine, as accurately as possible, the deformation characteristics of the masonry in the direction parallel to the bed joints. Experimental measuring of masonry samples was carried out in laboratory facilities designed specifically for testing the triaxial state of stress of the masonry. The obtained deformations were used to determine the modulus of elasticity of the masonry in the direction of bed joints. Within these experimental tests, laboratory measuring of mechanical masonry properties was carried out, and deformation characteristics were defined on the basis of calculations. The strengths of masonry units and mortar were tested in the laboratory and, according to the tests results, the modulus of elasticity in the direction perpendicular to bed joints was determined. The modulus of elasticity in the direction parallel to bed joints was verified through a simple numerical model. The calculated deformations were compared with the measured values. On the basis of the determination of the deformation characteristics of masonry in the direction of bed joints, the ratios of the modulus of elasticity in the direction perpendicular and parallel to bed joints were concluded.
Tests of fiber reinforced concrete composite slabs on the subsoil with horizontal load
(The Geomate International Society, 2020) Čajka, Radim; Mynarčík, Petr; Neuwirthová, Zdeňka; Marcalíková, Zuzana; Kropáček, Michal
Interaction between the soil and the structure is complex problematic. For the better understanding of the behavior of the flat concrete slab in contact with the subsoil series of tests were performed in the Faculty of Civil Engineering in Ostrava in the Czech Republic. This article focuses on the fiber reinforced concrete flat slab with dimensions 2000 x 2000 x 150 mm loaded by vertical and horizontal force. This loading is typical for building in undermined areas. The article describes the course, results, and evaluation of the experimental test, which was performed on special test equipment Stand over a four day period. The slab was exposed to a constant load of 100 kN in the vertical direction and about 50 kN in a horizontal direction. The deformations of the top surface of the slab were monitored by many sensors in both directions. Concrete deformation and cracks was also observed during the experiment. Deformation curves in the selected cross-section of the slab were evaluated from the measured data. Together with the experiment, the laboratory tests were performed from the same dough of concrete like the slab itself. The laboratory results are also present. The slab is compared to the vertically loaded slab with the same characteristics
Concrete structures interacting with subsoil depending on the use of sliding joint
(The Geomate International Society, 2020) Kropáček, Michal; Mynarčík, Petr; Čajka, Radim
Article describes the interaction of concrete structure (usually foundation structure or industrial floor) with subsoil, where unwanted friction occurs. Friction can be reduced with sliding joint. This generally known assumption is followed by research described in the article, which determines the effectiveness of sliding joints with respect to concrete volume changes on large-dimensional specimens. Large-dimensional specimens with dimension of 150 x 500 x 6000 mm were placed in the laboratory and outdoor environment, defining different boundary conditions. The research included various concretes in the same strength class and various sliding joints that respect the requirements of construction practice. The paper also describes the comparison of measured results with calculation models from technical standards and regulations, which allow calculation of volume changes on concrete structures. Regarding the subsoil and the sliding joint, this is one of the main long-term goals of the research, since the calculation models do not take these two parameters into account. Deformations from volume changes then deviate significantly from theoretical calculations, as friction in the sliding joint area affects the magnitude and course of volume changes. Practical results show that the steel fibres mixed into concrete have a positive effect on reducing volume changes in early stages of setting and hardening of concrete. Regarding the use of the sliding joint, the most important finding is that there are no significant differences from the selected sliding joints in the experimental part. In connection with friction, the use of the sliding joint itself has a significant effect.

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