Řada stavební. 2019, roč. 19 / Civil Engineering Series. 2019, vol. 19

Permanent URI for this collectionhttp://hdl.handle.net/10084/134878

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Now showing 1 - 20 out of 25 results

Future Development Assessment in Jablunkov Region
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Endel, Stanislav; Kutá, Dagmar; Kuda, Framtišek
The Jablunkov area is very specific in terms of territorial development. From the regional point of view, it is situated on the very eastern edge of the Czech Republic, which seems to be in a marginally not very important location. From a supra-regional perspective, however, it is close to a major transport route linking the North and South of Europe in an area surrounded by a mountain range. These seemingly contradictory facts have always influenced the area and at the same time determine its further development.
Modelling the Building Process using Software, Case Study
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Smugala, Stanislav; Kubečková, Darja
The execution phase of a construction project is often associated with interruptions of the construction process, which were not included in the original time schedule of the construction works. These interruptions may be caused by the links between the course of construction and operation and activity of the investor, where certain structures cannot be commenced according to their original schedules, or, for example, they are interruptions caused by weather conditions, when the temperature of the outdoor environment drops below + 5 ° C and most of the required technological processes cannot be performed. Also, during the construction, the necessity of performing additional works arises with a time requirement for their execution. The contractor is then obliged to prove to the investor the amount of time necessary to complete the contract, based on the unbuilt volume. The CONTEC automated building preparation system provides the possibility to accurately calculate the time required to complete building work, based on standard hours, the number of work crews employed, as well as based on technological links
Legion Bridge in Prague - Assessment of Stone Arches
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Vokál, Marek; Drahorád, Michal
The article deals with available engineering assessment methods for the stone vault bridges according to relevant standards. The article summarizes variable methodologies used for design and assessment of masonry vaults in last period. All methods were applied for assessment of the Legion Bridge over Vltava River in Prague and results were compared. The models were validated by results of static load test.
Uncertainties in Characteristic Strengths of Historic Steels Using Non-Destructive Techniques
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Sýkora, Miroslav; Mlčoch, Jan; Ryjáček, Pavel
The use of various non- or minor-destructive tests (NDTs) is often preferred to reduce the cost of structural surveys of historic structures made of cast and wrought irons or old carbon steels. This contribution thus explores the measurement errors associated with common NDT techniques and quantifies uncertainties in characteristic strength estimates based on NDTs only. It appears that a unity mean and coefficient of variation of 12% might be adopted for the measurement uncertainty of the methods under study (Brinell, Leeb, Poldi, Vickers, Rockwell). On average, the true characteristic ultimate strength is by ~15% larger than that based on many NDTs. This represents the expected gain when the characteristic value is estimated from five DTs instead of a large number of NDTs. In practice detailed reliability assessments should always be based on result
Identification of Mechanical Fracture Parameters of Alkali-Activated Slag Based Composites During Specimens Ageing
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Šimonová, Hana; Kucharczyková, Barbara; Lipowczan, Martin; Lehký, David; Bilek Jr., Vlastimil; Kocáb, Dalibor
The aim of the paper is to present the results of the experiment focused on the development of the mechanical fracture characteristics of alkali-activated slag (AAS) based composites within the time interval from 3 days to 2 years of ageing. Two AAS composites, which differed only in the presence of shrinkage reducing admixture (SRA), were prepared for the purpose of experiments. The composites were prepared using ground granulated blast furnace slag activated by water-glass with silicate modulus of 2.0, standardized quartzite sand with the particle grain size distribution of 0−2 mm, and water. Commercially produced SRA was added into the second mixture in an amount of 2 % by weight of slag. The test specimens were not protected from drying during the whole time interval and were stored in the laboratory at an ambient temperature of 21 ± 2 °C and relative humidity of 60 ± 10 %. The prism specimens made of the abovementioned composites with nominal dimensions of 40 × 40 × 160 mm with the initial central edge notch were subjected to the fracture tests in a three-point bending configuration. The load F and displacement d (deflection in the middle of the span length) were continuously recorded during the fracture tests. The obtained F−d diagrams and specimen dimensions were used as input data for identification of parameters via the inverse analysis based on the artificial neural network, which aim is to transfer the fracture test response data to the desired material parameters. In this paper, the modulus of elasticity, tensile strength, and fracture energy values were identified and subsequently compared with values obtained based on the fracture test evaluation using the effective crack model and work-of-fracture method.
Comparison of Mechanical Properties of Old Steel from Truss Crane Runway with S235 and S355 Grades
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Seitl, Stanislav; Miarka, Petr; Pokorný, Pavel; Fintova, Stanislava; Kunz, Ludvík
The nowadays the using of S235 J2 and S355 J2 steel grades in civil engineering to design structures elements of cranes, bridges, building structures or simple engineering parts allows material and economical savings meeting the strict construction requirements. The aim of this contribution was to determine the mechanical, fatigue and strength properties of the old steel from steel truss crane runway in Vítkovice Company. The second task was the comparison of obtain data from old steel with properties of standard used S235 and mild steel S355 and to make recommendations based on the results which steel grade can replace existing damaged elements made from old steel.
Stochastic Spectral Methods in Uncertainty Quantification
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Novák, Lukáš; Novák, Drahomír
Uncertainty quantification is an important part of a probabilistic design of structures. Nonetheless, common Monte Carlo methods are highly computationally demanding or even not feasible for this task, especially in case of mathematical models of physical problems solved by finite element method. Therefore, the paper is focused on the efficient alternative approach for uncertainty quantification-stochastic spectral expansion, represented herein by Polynomial Chaos Expansion. In recent years, an application of stochastic spectral methods in uncertainty quantification is the topic of research for many scientists in various fields of science and its efficiency was shown by various studies. The paper presents basic theoretical background of polynomial chaos expansion and its connection to uncertainty quantification. The possibility of efficient statistical and sensitivity analysis is investigated and an application in analytical examples with known reference solution is presented herein. Moreover, practical implementation of methodology is discussed and developed SW tool is presented herein.
Dynamic Behaviour of Railway Bridges under Moving Mass Load â€“ Iterative Modal Analysis
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Moravčík, Milan
Travelling mass due to its mass inertia has significant effect on the dynamic response of the bridges. This study is devoted to the study of the dynamic response the real steel railway bridge of the length Lb = 38 m for the single locomotive bogie mass load MLbg = 44 t (Škoda 350) passing over the bridge with the speed v=65 m/s. The iteration method of the governing partial differential equation of the transverse motion of the bridge structure w(x,t) has been applied. The modal superposition method for the vertical bridge deflection w(x,t) considering the first mode j=1 was used.
A Comparison of Crack Paths Growth in Brazilian Disc with a Central Notch Using Various Criteria for Crack Initiation
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Miarka, Petr; Furgieri, Guido; Růžička, Vladimír; Seitl, Stanislav; Merta, Ildiko
A numerical parametric study of the crack propagation under various level of mixed-mode conditions is evaluated. By focusing of the Linear Elastic Fracture Mechanics, the model with concrete input data of Brazilian Disc Test with a central notch is considered and its analysis with defined radius R, force P and material properties is performed. The results are obtained by varying the length an of the central notch and its angle of inclination α with respect to the horizontal axis. The crack growth direction is estimated through three different criteria: the maximum tangential stress criterion, the strain energy density criterion and the crack tip displacement criterion. This study involves the classical single-parameter fracture mechanics concept, in which the stress distribution in a cracked specimen is described by the stress intensity factors. The Williams solution of the crack-tip stress and displacement fields are taken into account. As a comparison, the solution is also provided with J-Integral. The model is created with the finite element method software ANSYS. Lastly, the suggested crack paths obtained by criteria are compared with experimental data.
Numerical Analysis of Brazilian Disc Test with a Central Notch: Constrain Level for Various Notch Inclination Angles
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Miarka, Petr; Merta, Ildiko; Seitl, Stanislav
The Brazilian disc test is widely used to determinate indirect tensile strength or fracture mechanical parameters of rocks, concrete and polymers. The fracture mechanical parameters evaluated from such a test provides information of mode I, mode II and mixed mode I/II fracture initiation. While the geometry functions for calculation of stress intensity factors are known, the Tstress values are lacking. Especially, the lack of T-stress can be noticed, when the T-stress equals to zero. This contribution aims to find crack inclination angle for which the T-stress values are close to zero and evaluate stress intensity factor for such an angle. For this, a numerical study was performed.
Analysis of the Mechanical Wave in the Composite Made of Concrete and Rubber - Numerical Analysis
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Major, Maciej; Major, Izabela; Kuliński, Krzysztof
In this paper dynamic numerical analysis concerning mechanical wave intensity reduction via rubber material insert/inject in a typical wall concrete block is discussed. Numerical model consists of a single block with a rubber strip and rounded cuboids inserted/injected from the top to the bottom surface of that block. Due to adopted rubber inserts/injects dimensions and cross section area, influence on concrete block compressive strength can be neglected. Mechanical wave propagation is forced through an impact of inclined concentrated force applied to the front block surface on the offset from side block surface. That impact load arises in a very small time step and furtherly its value is changed to zero. According to that mechanical wave propagation may be observed in the form of stress plots plotted in a given time step. Through the numerical analysis it is shown that in case of composite made of concrete-rubber there is a possibility to reduce the mechanical wave propagation by around 25% in comparison to the solid concrete block.
Stress Distribution in Spread Footing Foundations - Numerical Analysis
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Major, Maciej; Major, Izabela; Kuliński, Krzysztof
In this paper stress distribution in different shapes of spread footing has been discussed and an optimization of footing dimensions has been proposed. For the analysis purposes comparison of stress distribution has been performed for six different shapes of spread footing. Spread footings has been divided into two groups, where the first contained foundations with rectangular base and in the second one circular base has been considered, respectively. In both groups three different shapes of spread footing have been analysed – prismatic/cylindrical, prism with sloped edges/cut-off cone and stepped footing. For each spread footing in the centre of their top surface a small part of column has been modelled. Presented in this paper comparative analysis has been limited only to the pure axial loading subjected to the top surface of columns. In order to perform numerical analyses SolidWorks Finite Element Method (FEM) based software has been chosen. Through the analysis it is shown that the best stress distribution for the further weight and shape optimization is obtained in sloped prism and cut-off cone. After the optimization process of the spread footing dimensions one obtained a reduction of approximately 90% of total weight, with acceptable stress value increase.
Finite Element Modelling of Reinforced Concrete Slab Exposed to Extreme Fire Loads
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Jindra, Daniel; Hradil, Petr
Numerical approach using the finite element method has been used to determine the mechanical resistance (criterion R) of a reinforced concrete structure exposed to fire. Geometry of the structure is considered as a simply supported slab in one dimension. Fire load has been defined by a nominal standard ISO 834 fire curve. Both, thermal and structural response are obtained using a finite element method software ANSYS. Temperaturedependent nonlinear thermal and mechanical properties of concrete and reinforcement are adopted in accordance with Eurocode standards. Nonlinear material model Menetrey-Willam with exponential functions for compression hardening (and softening) and tension softening has been used to describe the behaviour of concrete elements. Discrete option of modelling reinforcement has been considered. Mechanical resistance of the slab is determined by reaching the limit mid-span deformation. Results have been compared with simplified method of isotherm 500 °C described in Eurocode.
Study of the Efficiency and Accuracy of Optimisation Algorithms within Inverse Identification of the Parameter Values of a Nonlinear Concrete Material Model
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Král, Petr; Kala, Jiří; Hradil, Petr
The inverse identification of the parameter values of nonlinear material models, which have been developed for, inter alia, concrete modelling, is currently a process that is widely used and investigated in the field of research and development. Today there are several approaches that can be employed for the inverse identification process. One of the most significant of these approaches involves the use of optimisation algorithms which, however, often demonstrate varying levels of precision and efficiency within specific tasks. These aspects are the subject of the research presented in this contribution.
Effectiveness of Glass Fiber Mesh Reinforcement Applied to Road Construction Located in a Mining Subsidence Area
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Kałuźa, Mateusz; Kotasiński, Miroslaw
Local district roads represent low technological regime when it comes to rehabilitation treatments. Analysed road is located in a mining subsidence area in Upper Silesia in Poland. Glass fibre mesh interlayer reinforcement had been tested numerous times at different roads. The main objective of this paper is to investigate the effectiveness of applied reinforcement for road located in a mining subsidence area. Evaluation was performed by determining a state of cracking indicator in accordance with visual-method of pavement surface evaluation. Results shows high effectiveness of applied reinforcement. Further researches are recommended.
Simulations as Part of the BIM Concept in Urban Management
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Faltejsek, Michal
Smart city management is part of the Smart Cities concept and can be an essential element for further development in this area. The BIM concept, based on a 3D model, data and for all the beneficial cooperation, expands exponentially in the civil engineering. However, the BIM concept is so broad and there are many possibilities in his area, that the development will take many years. One of these areas may be simulations that are not so widely used so far, but which can very well specify different situations and conditions. For these conditions, buildings or cities can be prepared in advance to prevent crises or unnecessary costs. The simulations and the results obtained from them can help us in the decision making phase. They predict problems or situations that can occur during the life cycle and thus prevent them from occurring. Based on the information we receive, we can objectively decide on the design solution, the material, the internal arrangement or, for example, the location of the building in the surrounding area.
Orientation of Blind and Visually Impaired People - Case Study
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Bílková, Alžběta; Kocurová, Petra; Zdařilová, Renata
This paper is focused on evaluation of barrierfree accessibility of the significant regional transfer junction in Ostrava made up of the Ostrava-Svinov railway station and upper and lower stops of the urban mass transportation. The outcome is focused on solving the problems of movement and orientation of blind and visually impaired people. Public transport is an important part of public area of cities and municipalities. The most important part of public transport happen the transfer junctions. Thanks to intensive utilisation of these transfer areas, it is necessary to assess these places, among others, also in light movement of man in all of his life stages and primarily in light of barrier-free accessibility.
Laboratory Tests Of Waste Mixtures Consisting Recycled Tyre Rubber and Coal-Mining Wastes
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Ciolczyk, Adrian; Walotek, Konrad
The paper presents the results of research on the application of recycled tyre rubber, in the form of rubber dust, in mixtures bound with a hydraulic binder, to improve the physical and mechanical parameters of unburnt coalmining slates. In particular, the parameters related to resistance to water and susceptibility of bound mixtures. The research was carried out on mixtures containing unburnt coal-mining slate, rubber dust, fly ash and cement, as well as on reference mixtures with no rubber dust in their composition. The observations were aimed at checking how the varied content of rubber dust affects the physical and mechanical parameters of the samples.
Sports Hall - Warranty Defect of Floor
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Smugala, Stanislav; Kubečková, Darja
The paper examines the issue of managing complaints after buildings have been put into operation. The problem is documented through the case study example “Sports Hall Reconstruction”, in which a fault appearing in part of a large concrete slab is described. The construction of large concrete slabs to form the base floor layers in sports and industrial buildings is often accompanied by numerous problems. Achieving an even structure in the final surface is one of the main problems on account of the large amounts of processed concrete used. Construction of the base layers beneath concrete floors using the materials prescribed by project documentation therefore demands considerable attention. Technological discipline in processing concrete mixtures in relation to potential shrinkage cracking or cracks caused by improperly installed expansion joints is an equally important part of industrial flooring construction.
Implementing Snow Load Monitoring to Control Reliability of a Stadium Roof
(Vysoká škola báňská - Technická univerzita Ostrava, 2019) Sýkora, Miroslav; Diamantidis, Dimitris
This contribution shows how monitoring can be used to control reliability of a structure not complying with the requirements of Eurocodes. A general methodology to obtain cost-optimal decisions using limit state design, probabilistic reliability analysis and cost estimates is utilised in a full-scale case study dealing with the roof of a stadium located in Northern Italy. The results demonstrate the potential of monitoring systems and probabilistic reliability analysis to support decisions regarding safety measures such as snow removal, or temporary closure of the stadium.

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