Řada stavební. 2022, roč. 22 / Civil Engineering Series. 2022, vol. 22

Permanent URI for this collectionhttp://hdl.handle.net/10084/146429

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Now showing 1 - 19 out of 19 results

Effect of Different High-energy Grinding Technologies on Granulometric and Crystallographic Properties of Portland Cement
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Rawaszová, Simona; Dvořák, Karel
The present article deals with the effect of different high-energy grinding technologies through available laboratory mills on Portland cement's granulometric and crystallographic properties. Two types of commonly available laboratory mills were selected, namely the planetary mill and the vibratory mill. The type of laboratory mill used, the grinding environment, and the grinding time were monitored. The planetary laboratory mill with 10 mm in diameter grinding steel balls proved to be more efficient in the scope of material reduction, which effectively reduces the material, especially during wet grinding of the material. The agglomeration effect is significantly reduced, which is a big advantage of method of wet grinding.
Behaviour of Wood Joints Glued by One Component Polyurethane Adhesive Modified by Cotton Flakes and Basalt Fibers
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Laciková, Petra; Vaněrek, Jan; Běťák, Adam
The main objective of this paper is to describe the influence of cotton flakes and basalt fibers on the resulting tensile properties of one-component polyurethane and the tensile shear strength of glued lap joints of beech wood. Fillers are an integral part of the modification of adhesives, especially because they influence rheological and mechanical properties. A one- component polyurethane adhesive for waterproof joints was used for bonding. The amount of filler was optimized by determining the tensile properties of adhesive as a material. The basalt fibers improved the tensile properties of one-component polyurethane. The average tensile strength value for basalt fibers in the amount of 5% was found to be 30% higher than for basalt fibers in the amount of 1%. The resulting properties of glued joints were determined by tensile shear strength according to standard ČSN EN 302-1. It was found that the shear strength of the bonded beech joints was higher for modified one-component polyurethane by cotton flakes than those modified by basalt fibers of 7 mm length. Significant effect was shown for cohesive failure of lap joint especially for modification by cotton flakes when the value increased by 10% to reference wood joint.
Determination of Pozzolanic Activity of Thermally Activated Brick Loam
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Kepper, Martin; Pommer, Vojtěch; Šádková, Kateřina; Koňáková, Dana
Supplementary cementing materials (SCM) present of one of possible ways how to reduce the energy consumption and related CO2 emissions from Portland cement production. There is number of more or less stablished SCM. These may be by-products of another production technologies (blast furnace slag, coal fly ash), natural materials (certain volcanic rocks) or produced materials (calcined clays).Metakaolin (MK) – thermally activated kaolin – belongs to the widely studied SCM. Its main drawback is relatively high price, caused partially by the rather “exclusive” raw material – kaolin. The research on thermal activation of more abundant clay raw materials to SCM may raise the application potential of clay-based SCM. This paper deals with thermal activation of a brick loam. The loam under study contains all principle clay minerals (kaolinite, illite, montmorillonite) accompanied by quartz and feldspars. The loam was characterized by thermogravimetry and XRD. Then it was activated at three temperature levels (500, 550 and 600 °C) and the pozzolanic activity was determined by Saturated Lime Test. It was found that all three materials are fixing considerable amount of Ca 2+ ions, but probably not only by pozzolanic reaction, but also adsorption on clay minerals plays a role.
Ponding Effect: Nonlinear Loading on Tensile Surface Structures
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Zajac, Zbyněk; Lang, Rostislav; Němec, Ivan
This paper deals with a potentially danger- ous phenomenon known as the ponding effect that may occur on tensile surface structures. This phenomenon may cause a local disorder that might lead to a fatal damage and collapse of the structure. The aim is to create and verify a searching algorithm in order to lo- calise a possible ponding effect occurrence. Its main purpose is to scan the membrane surface deformed un- der snow load and locate areas prone to accumulation of melted snow. Thereafter the area of water pond is cal- culated and the area is loaded with an additional weight. A verification is made on the conical structure consid- ering a variety of height to length ratios.
Computational Intelligence in the Analysis of Local Climate and Its Predictions
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Walentyński, Ryszard
Computational Intelligence in the Analysis of Local Climate and Its Predictions
3D Scanning as an Effective Tool for Controlling the Dimensions of Test Specimens
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Vyhlídal, Michal
3D laser scanning is a powerfull tool that digitally captures the shape of physical objects using a laser light crosses. In this work, the 3D laser scanning technology is used for the 3D shape capture of specially designed specimens. These specimens pre- viously made of fine-grained cement-based composite of the nominal dimensions 40 × 40 × 160 mm with in- clusion in the shape of prisms with nominal dimen- sions of 8 × 8 × 40 mm were provided with an initial central edge notch and tested in the threee-point bend- ing configuration. The aim of this paper is to study the macrostructure of fracture surfaces via 3D scanning technology, measure the area of ligament, verify the de- signed notch depth and evaluate the fracture tough- ness and specific fracture energy based on the mea- sured dimensions. The results indicate that the mea- sured notch depth is lower than the designed one thus the differences between fracture toughness calculated for designed notch depth and for the measured one is ap- proximately 10 %. In addition, the fracture toughness is overestimated when considering the design values.
Variance of Selected Properties from Various Structural Elements Made from AISI 304
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Seitl, Stanislav; Pokorný, Pavel; Benešová, Anna; Juhászová, Tereza; Kala, Zdeněk
Stainless steels, especially AISI 304 are widely used civil engineering materials because of their excellent properties. They are used/applied in many civil engineering structures (chemical, energy, bridges etc.). The presented study aims to quantify variance of selected properties from various structural elements made from AISI 304. This study shows that the mechanical and fatigue properties of AISI 304 steel used in construction and supplied in different profiles from different suppliers can vary considerably, which must be taken into account when designing structures or its service-life.
Analysis of the Use of Tensegrity as Display Postuments in Museums
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Palacz, Przemyslaw; Major, Izabela
Tensegrity structures, due to their high stiffness and lightness, have been interesting for designers and architects for decades. The key stage of each design is the selection of the optimal structural system, the task of which is to ensure the load-bearing capacity and meet the visual expectations of modern museums and traditional exhibitions. The article analyzes the use of the tensegrity structure as display pedestals in museums due to its stability and load-bearing capacity. Numerical calculations of the analyzed structural systems of museum pedestals were performed using the finite element method in RFEM. After the analysis, it can be concluded that a properly selected tensegrity structure for the construction of a museum pedestal is an interesting solution worth considering when designing.
Fracture Parameters of a Perpendicular Crack with Its Tip Close to a Corrosion Pit
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Malíková, Lucie; Doubek, Pavel; Juhászová, Tereza; Seitl, Stanislav
Pitting corrosion is an important kind of damage of metal specimens. Therefore, this paper is devoted to investigation of mutual interaction of a corrosion pit and a fatigue perpendicular crack. A rectangular specimen subjected to remote tensile loading was modelled via finite elements and basic fracture parameters were calculated for various distances of the pit from the crack. Based on the obtained dependences of KI , KII (stress intensity factors for normal and shear modes) and B (parameter biaxiality) on the relative crack lengths (a/W), it can be summarized that the corrosion dimple is significant for the crack propagation only if the relative crack length is very short in comparison with the corrosion pit. Then, the corrosion pit can affect as a protection against the crack propagation.
Probabilistic Assessment to Analyse of Soil Structure Interaction of Tall Buildings
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Králik, Juraj; Králik, Juraj
This paper presents the results from the deterministic and probabilistic analysis of the accidental torsional effect on seismic resistance of the tall building. The methodology of the seismic analysis of the structures in Eurocode and JCSS is discussed. The possibilities of the utilization the RSM and LHS method to analyse the extensive and robust tasks in FEM is presented. The influences of the local site effects – masses, stiffness, and thickness of the layered subsoil - can significantly modify the stresses and deflections of the structural system. The influence of the uncertainties of the input and output parameters is considered. The deterministic and probability analysis of the seismic resistance of the structure was calculated in the ANSYS program.
Determination of Critical Length Parameter for Fatigue Lifetime Predictions of Notched Specimens
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Kozáková, Kamila; Klusák, Jan
Determination of Critical Length Parameter for Fatigue Lifetime Predictions of Notched Specimens
Diagnostic and Analysis of Selected Masonry Railway Bridges on Slovak Railways
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Kotula, Patrik; Koteš, Peter; Kridla, Ondrej; Vavák, Branislav
The paper presents an overview of the current state of railway masonry arch bridges that are in operation on Slovak Railways. The material of the vault is either stone or brick. It also presents the current possibilities of diagnostics, monitoring and evaluation of failures, the method of measuring selected material characteristics of masonry elements (especially the determination of compressive strength). Within the cooperation of our department and the Research and Development Institute of ŽSR, applications of diagnostic measurements and evaluation of the current state of these bridges are presented on selected bridge structures.
Analysis of the Impact and Mechanical Properties of a Damper Made of Hyperelastic Material
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Koteš, Peter; Vavruš, Martin; Zahuranec, Michal; Prokop, Jozef
The proof-load tests are an integral part of verifying the actual behaviour of bridge objects. If a new bridge object is put into operation after construction, it is necessary to verify whether it will behave as it was supposed to when it was designed. In the case of existing bridge objects, it may happen that the bridge has malfunctions or behaves unconventionally due to failures - then there may be a need to reconstruct and strengthen the bridge object, and thus again there is a need to verify its behaviour using a proof-load test. The proof-load test can be static or dynamic. The aim of the paper is to point out the inevitability of the proof-load tests for the real and correct behaviour of bridge structures in ultimate limit state and maximum allowable deformations in serviceability limit states. It is necessary to point to the greatest consequences of resistance, reliability, durability and lifetime of the bridge structures. Using the proof-load tests for new bridges is prescribed by the Slovak standard STN 73 6209.
Analysis of the Impact and Mechanical Properties of a Damper Made of Hyperelastic Material
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Jaskot, Anna; Major, Maciej
The analysis of mechanical properties in the proposed model of the vibration damping element through the use of a layer of hyperelastic material was presented in the paper. The aim of the study was to analyse the behaviour of the structure under the influence of external forcing forces with the use of hyperelastic materials, which are characterized by high compressive fatigue strength. The model in its construction assumes the use of rubber as a material that acts as a vibration damper. The results presented in the paper include the stress-strain relationship and the vibration analyses. The paper contains the conclusions of the comparative analysis in relation to the reference model. The studies were performed using the finite element method using the ANSYS program. Mesh elements were adopted as 3D solid elements, adapted to the model, and properly densified in the places of contact of individual layers in the model. The Mooney-Rivlin material model, in order to analyze the middle layers, was adopted in the work.
Starting Points and Creation of Auxiliary Software for Designing Cemetery Complexes Relevant to the Current Needs of Society in the 21st Century in the Czech Republic
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Juračka, Ondřej; Palánová, Klára
The main topic of the published research is the design of cemeteries in the context of social change in the 21st century in the Czech Republic. This is complex presentation of the principles of designing cemeteries and their auxiliary buildings. To this end, individual component researches were carried out, which captured the development of cemetery structures and crematoria in the Czech lands since the so-called Josephine reforms. At the same time, data were obtained from existing and historic cemeteries and buildings that have undergone a period of transformation over the last 100 years. The main output is a developed program called “HOK” in the MS Excel environment, which summarizes all the principles of research in the design of cemeteries and operations of the ceremonial hall or crematorium. The program’s entire assembled environment is customized to be user-friendly and to provide practical designing benefits. The article introduces the key points of the research results and related analyses, and at the same time presents working with the newly developed software and its possible implementation in design practice focused in this article to the cemeteries.
Cemeteries as Parts of Sustainable Cities: Their Current State and Future Needs
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Palánová, Klára; Juračka, Ondřej
City cemeteries are one of the typical parts of cities that can play several important roles in the life and development of a city. Some are located on the outskirts, others near the centres of modern cities. They should be carefully included in the city's development plans to exploit their potential in terms of isolated green spaces. However, most municipal authorities usually pay very limited attention to them, and the background of the Czech secularised society also has a significant effect on the low attendance and care of cemeteries. This leads to neglected care for them and vandalism in these areas. The article aims to find out the interest in cemeteries among the general public and focus on their further use in the city for their sustainability. The research focused on the cemeteries of Ostrava, the third largest city in the Czech Republic, where it examined their current state and possibilities for their improvement in order to fulfil their current and future role. The identified weaknesses will help manage the transformation of cemeteries so that they remain a full-fledged part of Central European cities. The conclusions suggest architectural and other changes to cem
Sandwich Composite Panels With Gfrp Face Sheets â€“ Experimental Analysis, Numerical Simulation and Analytical Solution
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Pešek, Ondřej; Simon, Pavel; Balász, Ivan; Horáček, Martin
This paper deals with the problem of analysis of beams made of SCP (sandwich composite panel) composed of GFRP face sheets and foam core. In the frame of research project, several specimens of different compositions were tested by four-point bending according to the actual standard. Nonlinear behaviour was observed in some specimens and possible reasons are discussed in the paper. SCP beams were also numerically simulated using the finite element method in ANSYS Workbench software. For practical and easy engineering design (prediction of deformations and stresses) the analytical procedure was developed for linear and nonlinear behaviour. Results represented by P-Δ and P-σ diagrams of experimental, numerical, and theoretical analysis are compared together in this paper. Based on the analytical solution the parametric study was performed to find out the optimal composition of SCP members for specific static boundary conditions.
An Approach for Accurate Measurement of Fractal Dimension Distribution on Fracture Surfaces
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Frantík, Petr
The paper describes a new approach to measuring the box-counting fractal dimension of surfaces based on making cuts and using the walking divider method with an improvement. The method is applied on a surface created by the fracture of an artificial composite. It is usable for accurate estimation of fractal dimension of flatter surfaces for which it is necessary to measure with small deviation. It also allows the discovery of the dimension distribution along the surface.
Numerical Analysis of Influence of Axial Force on Resistance of Column Webs in Transverse Compression
(Vysoká škola báňská - Technická univerzita Ostrava, 2022) Balász, Ivan; Pešek, Ondřej; Vild, Martin
Steel members of double-symmetrical open cross-sections are often used in engineering structures and structures of buildings as columns and beams. Due to connections of the members, transverse compression of the cross-section webs can occur and is subject to structural assessment. The resistance of the column web is influenced by structural solution of the joint (welded, bolted, with end plates) and possible interaction with axial force in the column or shear. The paper focuses on numerical investigation and quantification of the influence of axial force in the column on behaviour and resistance of the column web in transverse compression. The analysis was performed using finite element method based computation system and included both rolled and welded cross-sections with various values of relative slenderness of the web. The results were compared with results of transverse compression resistance calculated using actual standard for design of steel structures.

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