Řada stavební. 2021, roč. 21 / Civil Engineering Series. 2021, vol. 21

Permanent URI for this collectionhttp://hdl.handle.net/10084/145073

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Now showing 1 - 20 out of 21 results

Advantages of Tensile Structure Analysis During Construction Stages
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Zajac, Zbyněk; Lang, Rostislav; Němec, Ivan
This paper deals with the importance of analysing tensile structures during individual construc- tion stages. This type of analysis is usually related to conventional structures. However, results of the re- search on this topic imply that problems caused by an insufficient design are solved on a building site on a daily basis. It usually is the engineer’s responsibility to find a proper solution and a method of construction. A challenging decision is strongly dependent on expe- rience and current status. This research contributes to a more detailed description of the problem.
Effect of the Mechanical Fracture Parameters of Inclusion on Fracture Behaviour of Cement Composite
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Vyhlídal, Michal
This paper concerns the results of research into the effect of the mechanical fracture parame- ters of inclusion material on the fracture response of specially designed cement-based composite speci- mens. These specimens of the nominal dimensions 40 × 40 × 160 mm with inclusion in the shape of prisms with nominal dimensions of 8 × 8 × 40 mm were pro- vided with an initial central edge notch and tested in the threee-point bending configuration. The aim of this paper is to analyse the effect of the mechanical fracture parameters of inclusions material on the ef- fective mechanical fracture parameters of cement-based composite. The results of this research indicate the de- pendence of the effective mechanical fracture parame- ters of cement-based composite on the Young’s modulus of inclusion material.
The Importance of Mesh Module in Fem Analysis of Push-out Tests
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Vaňová, Patrícia; Kvočák, Vincent
Standard push-out tests are nowadays often performed by many researchers around the world in order to determine the elastic shear resistance of the selected shear element. La ter, these experiments are modelled in several softwares based on finite element method (FEM). The main toping of this article is the importance of choosing the right mesh settings for such analysis – shape, curvature control and specifically size. Their effect is closely described below.
Application of Semi-probabilistic Methods to Verification of Series System
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Sýkora, Miroslav; Marková, Jana; Nadolski, Vitali
Non-linear finite element analysis (NLFEA) has become a widely used tool in the reliability verification of reinforced concrete (RC) structures. Reliability assessment of RC structures is a challenging task and simplified approaches to reliability verifications are needed to allow for routine applications. Simplified semi-probabilistic methods such as the partial factor method (PFM) or the Method of Estimation of Coefficient of Variation (ECoV) may yield over- or under-conservative approximations. This contribution investigates such errors related to the applications of these two methods to series systems; the design resistances obtained by the probabilistic approach are considered as a reference level. It appears that PFM provides good approximations as the method is focused on critical members in the cases under consideration. ECoV may overestimate up to 20% in situations where NLFEA based on mean and/ or characteristic values fails to identify a dominating failure mode. The maximum observed error is attributed mainly to the failure in identifying the type of distribution of the system resistance. The presented limited analysis indicates several directions for further research (analysis of other types of structural systems, cases with non-lognormal resistances, effects of a number of system components, and their mutual correlations, and performance of advanced methods for reliability verification). Recommendations on how to identify situations when a significant error can be expected should be provided for practical applications of simplified semi-probabilistic methods.
Some Aspects of Designing and Numerical Modelling of Glass Railing Exposed to Impact Load
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Pešek, Ondřej; Melcher, Jindřich
in recent architecture glass is widely used structural material of facades, walls, roof, stairs and other applications. Glass as a material is popular for its transparency, but it need to be carefully analysed for its fracture behaviour. This paper deals with some aspects of numerical modelling and designing of all-glass railings acting as cantilever element fixed at the bottom edge and with a handrail on the top edge. In the frame of study, number of different glass railings models were analysed to find out the best way how to simulate glass railing imposed to the impact load. The impact load is in most cases decisive load case acting on that type of structure. Variable parameters entering the analysis are the aspect ratio of glass railing pane, impact intensity, impact member hardness and finite element meshing. Finite element analysis of 250 models was performed in ANSYS Workbench.
Assessment of the Possibility of Using the Tensegrity System in the Steel Tower Structure
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Palacz, Przemyslaw; Major, Izabela
Tensegrity structures, due to their lightness and high stiffness, have been popular among architects and constructors for many years. When designing building and engineering structures, the most important stage of designing is the selection of the appropriate structural system depending on the purpose and location of the designed facility. When selecting the load- bearing structure, designers are guided by the smallest possible weight of the structure, while ensuring the safe operation of the facility, meeting all strength conditions. The article presents an analysis of the effectiveness of using the tensegrity structure for the load-bearing structure of a tower in a steel structure. The assessment of effectiveness was carried out taking into account the economy of execution and the fulfillment of the ultimate and serviceability limit conditions of individual elements of the structure for the load-bearing system of the tensegrity structure. Numerical calculations and cross-section dimensioning were performed using the finite element method in RFEM, modeling the structure in 3D.
Comparison of Approaches to Reliability Verification of Existing Steel Railway Bridges
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Nadolski, Vitali; Holický, Milan; Sýkora, Miroslav
Many existing steel railway bridges are exposed to degradation and increasing traffic loads. Their reliability assessment may contribute to sustainability in construction particularly when these bridges are kept in service. The sustainability aspects mainly relate to reducing waste material and to unnecessary replacements of existing bridges. The key aspects of assessment include specification of the target reliability and selection of an appropriate assessment method. The most efficient verification methods are based on advanced probabilistic approaches. The application of the adjusted partial factor method seems to be reasonable as it provides the balance between demands on the input information, computational complexity, and achieved improvements in reliability assessment. In this contribution, the advanced reliability approach is illustrated by an example of the assessment of a 90-years old steel railway bridge. This case study demonstrates that advanced reliability approaches may significantly improve assessment and allow to increase the estimated load-bearing capacity of the bridge by 10 to 20%.
Influence of Thickness on the Values of Stress Intensity Factor in Compact Tension Specimen
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Fernandez, Germana; Miarka, Petr; Seitl, Stanislav
It is well known that value of fracture toughness depends on the thickness of studied specimen. This paper deals with an assessment of the influence of the thickness on the values of stress intensity factor measured at crack tip in the compact-tension specimen. For this a numerical model was assembled representing different specimen’s thicknesses and material characteristics. From this 3D numerical model, the SIF values were calculated using by direct extrapolation method.
Concrete Slab Response on Moving Load
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Melcer, Jozef
The subject of the article is a numerical simulation of the dynamic response of a concrete slab on an elastic subsoil on the effect of moving vehicle. The vehicle model and the slab model on Winkler and Pasternak subsoil are described. The method of calculating the subsoil constants for both models is presented. The numerical solution is carried out in MATLAB using the ode45 procedure. Considerations are made about the suitability of the used models and possible corrections of results for the Pasternak's model are presented. The results of the solution are presented in numerical and graphical form.
Fracture Tests of Multiple Specimen Sizes: Mechanical Fracture Parameters of C30/37 Concrete by Inverse Analysis
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Lipowczan, Martin; Šomodíková, Martina; Lehký, David
The paper presents a part of the research aimed at developing a comprehensive experimental– computational methodology for determining the values of mechanical fracture parameters of concrete independent of the specimen size and geometry. To this end, laboratory fracture tests in three-point bending and wedge-splitting test configurations were carried out using three different specimen sizes with two well-separated initial notch depths. The test records were used to identify selected mechanical fracture parameters using inverse analysis. Identifications were performed for individual specimens of each test configuration followed by statistical evaluation for individual sizes, notch depths, test configurations and for all specimens tested. The obtained parameters were used in the numerical simulation of the tests and the resulting load vs. displacement diagrams were compared with the experimental ones. The parameters were also analysed in terms of their dependence on the size of the initial uncracked ligament. As expected, a significant dependence of the fracture parameters was confirmed.
Probabilistic Nonlinear Analysis of Steel Frame Safety Under Extreme Wind Impact
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Králik, Juraj; Králik, Juraj
This paper describes the methodology and the results of the safety analysis of the Nuclear Power Plant (NPP) structures under impact of the extreme climatic loads. In the case of the NPP structures, the design criteria are stronger. The requirements of the international agency IAEA and NRC standards are based on the probability of mean return period equal to one per 10 4 years. This probabilistic assessment of NPP structures for Probabilistic Safety Analysis (PSA) level 2 of VVER 440/213 in the case of the extreme wind impact is presented. On the base of the meteorological monitoring of the locality the extreme load parameters were defined for the return period 10 4 years using the Monte Carlo simulations. There is showed summary of calculation models and calculation methods for the probability analysis of the structural resistance. The wind load was determined using the fluid analysis in software FLUENT in ANSYS and experimental analysis in wind tunnel. The general purpose of the nonlinear probabilistic analysis of the NPP structure resistance was to define the safety level of the critical structure elements. The numerical simulations on the base of the LHS method were realized in the system ANSYS and FReET.
The Prediction of Fatigue Life of Notched Specimens
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Kozáková, Kamila; Klusák, Jan
The contribution presents a method for lifetime predictions of components with notches. The method was developed using experimental data gained on smooth and notched samples and numerical analysis of notched specimens. The method employs approaches of generalized fracture mechanics and uses a critical length parameter. Emphasis is placed on the area of gigacycle fatigue.
Fatigue Behaviour of a Short Crack in a Thin Protective Layer Laser-cladded on a Steel Substrate
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Juhászová, Tereza; Malíková, Lucie; Doubek, Pavel; Miarka, Petr; Seitl, Stanislav
Fatigue behaviour of a short crack in a thin protective laser-cladded laye r has been investigated. A two-dimensional finite element model of a steel bar with two thin cracked layers on its both sides was created. Propagation of a crack under pure tension and pure bending was studied via linear elastic fracture mechanics concept considering various Young’s modulus of the surface layers. The effect of the elastic mismatch between both materials is demonstrated considering the critical stress intensity factor range of 20 to 25 MPa·m1/2 as it is typical for aluminium alloys. It is shown that more compliant materials enhance the critical crack length that causes the unstable crack growth and therefore also the lifetime of the component with laser-cladded protective layers.
Analysis of Forced Vibration Damping With the Use of Hyperplastic Materials
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Jaskot, Anna; Major, Maciej
A solution of forced vibration damping through the use of hyperelastic materials have been proposed in the paper. Most structures can be easily simulated on the basis of a linear elastic material model. However, when linear elasticity ceases to be sufficient, then nonlinear models are adopted, e.g. hyperelastic materials. The aim of this study was to investigate the behavior of the structure under the influence of external forces with the use of materials showing high fatigue resistance to compression with simultaneous consideration of vibration damping. The model presented in the paper has been subjected to an excitation in form of displacement. The paper presents a dynamic analysis using the finite element method in the ANSYS program. The comparison concerned the use of hyperelastic materials with the use of the deformation energy model of hyperelastic incompressible materials according to the Mooney-Rivlin model.
Design of Membrane Structure as a Temporary Roofing System
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Freiherrova, Nela; Juračka, David; Kawulok, Marek; Čajka, Radim; Krejsa, Martin
This contribution is focused on the design analysis of membrane structure and finding an optimal shape of such structure due to the surrounding possibilities with using numerical modeling. The membrane structure is designed for roofing of the experimental stand, which is in the campus of Faculty of Civil Engineering, VSB – Technical University of Ostrava and is currently not protected against unfavorable weather conditions. Design of membrane structures as temporary or permanent roofing has recently become very popular because of its shape variability, very low weight, and possibility of large spans. However, in addition to aesthetic requirements, structural and dispositional requirements are also necessary to consider on the same level during the design. The aim of this paper is to give an overview of the design of the temporary membrane structure starting from the architectural visualization and continuing to deal with structural and dispositional parts of the design using the RFEM software which has special add - on module for nonlinear analysis of membrane structures, RF Form - Finding.
Nonuniform Torsion Without Shear Deformation Effect Using FEM
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Tran, Dang-Bao; Navrátil, Jaroslav
This paper presents the use of a finite element method (FEM) to analyze nonuniform torsion with an arbitrary cross-section with homogeneous elastic material without shear deformation effect. Beams are constrained by the most common types of supports, such as fixed, pinned, and roller, and are subjected to any applied torsional load, concentrated, and distributed. The presented FEM transforms the 3D analysis of nonuniform torsion beams into separated 2D cross-sectional and 1D modeling. The geometric constants of the cross-section are firstly derived from 2D FEM, which uses a 9-node isoparametric element. Then, a 1D FEM, which uses the Hermitian shape function, is developed for computing the twist angle, the derivative of twist angle, 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 through examples. The validation examples have proven the reliability of the author's numerical method for analyzing problems defined above.
Negative Shear Lag Effect in Continuous Double T Beam by FEM
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Tran, Dang-Bao; Navrátil, Jaroslav
This paper presents the use of a finite element method (FEM) to analyze the negative shear lag effect on prestressed continuous double T beam. However, the numerical method can be applied to i) any cross-section, ii). the most common types of supports, such as fixed, pinned, roller, iii) and any applied load, concentrated, or distributed passed through the shear center of the crosssection. 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.
Castle Hnojnik as a Landscape Forming Element
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Augustinková, Lucie
The article is focused on the history and building development of the Hnojník castle and its neighbourhood. Especially the urban changes are observed. The basis of this article comes from the Historic Building Investigation of the Hnojník castle.
Influence of Artificial Waste Modification on Strength of Cementitious Composite
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Kocot, Agnieszka; Ponikiewski, Tomasz
High development of civilisation leads to incremental growth of produced municipal wastes. Despite of introducing restrictions related to municipal selective waste management still great amount of wastes is being landfilled. In countries like India or Philippines engineers started to utilize plastic wastes in extraordinary way using it as an alternative aggregate in cementitious composites. Many researchers tried to improve properties of concrete containing artificial aggregate. This paper analyses various treatment of PET flakes before adding to the mortar mix. Main aim was to modify the surface of PET flakes in order to obtain improved adhesion between artificial aggregate and cement matrix. Mortar mixes contained boiled, stored in alkali and acid solutions and regular plastic particles. This paper presents the results of flexural and compressive strength after 28 days and SEM analysis. Replacing natural aggregate in mortars with 5% PET flakes resulted in decreasing the compressive strength by 7%. Although the surface of PET flakes modified by alkali and acid solutions appeared to become rougher there was no improvement in compressive strength, moreover decreased in comparison to control sample.
Numerical Simulation of Wind Flow Using the Dlubal RWIND Tool
(Vysoká škola báňská - Technická univerzita Ostrava, 2021) Kawulok, Marek; Krejsa, Martin; Pospíšil, Stanislav
This article is aimed at current methods of calculating wind loads in structural engineering for construction, where these values cannot be clearly established by standard procedures. A suitable tool for these cases can be, for example, computational software for numerical simulation of wind flow around the structure, which allows the results of the simulation to be directly implemented to the numerical model as a load. The article introduces software for numerical simulation of wind flow and determination of induced force effects on the object of the high-rise building. The resultant force determined by the software was compared with a simplified calculation carried out according to the currently valid standards for determination the actions of wind on the structure.

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