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Analysis of Reinforced Concrete Beams Subjected to Impact Loading
Dvořák, Tomáš
The utilisation of complex nonlinear material models for concrete in numerical simulations is necessary for the accurate representation of structural behaviour. However, the successful modelling of such complex behaviour depends on a good understanding of the material model parameters. This paper deals with the critical issue of material parameter sensitivity in the context of RC beams subjected to impact loading. The objective was to establish relationships between the material parameters and the responses, including deformations and stresses, using sensitivity. This is the main key to understanding the complex interaction of these parameters and their influence on the structure.
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Influence of Membrane on Airflow in Historical Attic Spaces: The First Principles Study Using CFD Models
Poljak, Michal ; Ponechal, Radoslav ; Krušinský, Peter
This paper conducts an initial analysis of the impact of a vapour permeable membrane on airflow within triangular attic spaces, resembling the shape and dimensions of medieval sanctuaries found in historical rural churches in our region. The first principles study, using Computational Fluid Dynamics (CFD) based on the simulation models, aims to identify potential challenges and research directions regarding how the application of this membrane may affect the microclimatic conditions in the attic spaces and the durability of the historical timber trusses. One significant outcome of the study reveals that on a simulated extremely hot summer day, the application of the vapour permeable membrane reduced airflow by 10 to 15 per cent, thus affecting the overall microclimate in the attic.
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Aqueous CO2 Sequestration for Low-Carbon Ready-Mix Concrete
Chong, Yujie, Jamie ; Chua, Guan Feng ; Zhao, Mingshan ; Yip, Colin ; Daneti, Saradhi Babu ; Jin, Fei
The cement industry accounts for 8% of global energy- and process-related greenhouse gas emissions. To achieve global net-zero emission targets by 2050, the need for commercially ready low-carbon construction materials is becoming increasingly urgent. The fixation of captured carbon dioxide in concrete through CO₂ sequestration is a crucial area of study to reduce concrete embodied carbon. This paper discusses the development of a low-carbon ready-mix concrete (RMC) with aqueous CO2 sequestration, and the synergy between carbon dioxide and other constituent materials. The effectiveness of this approach was evaluated through mineralogical composition analysis using TGA, and the mechanical and rheological properties of various concrete mixes were studied. Aqueous CO2 sequestration using carbonated mixing water can stably fix up to 0.84% of CO2 by weight of cement within the cement matrix as CaCO3. The poor workability and incompatibility with GGBS that results from this approach were addressed by the inclusion of RCA as an external source of alkalinity and lubrication. This mix of low-carbon RMC has similar strength and rheological properties to conventional RMC and achieved an embodied carbon reduction of approximately 47%.
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Noise Protection from Sanitary Installations
Svoboda, David ; Berková, Petra ; Čupr, Karel
This review article deals with noise and vibration arising from the operation of sanitary installations – wastewater and freshwater plumbing. The first part describes the most commonly occurring sources of noise and vibration from such installations and possible ways of propagation. The second part sets out the measurement methodology and the differences in legislative requirements among countries. In the third part of the paper, principles of noise protection and modifications to sanitary installations are described.
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Mould Risk on Wall Surface in Partly Underground Technical Room
Nováková, Iva ; Šikula, Ondřej
This conference article aims at the indoor climate in the technical room of an underground water reservoir. This indoor climate is specific by high relative humidity (average 75.2% r.h.) and low air temperature (average 13.6 °C). Therefore, this research study focuses on surface condensation and mould risk on the partly underground wall in the technical room. The experimental research combines long-term monitoring (22 months). Long-term of indoor climate and thermal numerical simulation. The experimental measurement shows condensation risk on the indoor wall surface, and the unsteady 2D numerical simulation in software Calculation Area 4.0e shows temperature fluctuation on indoor wall surfaces. Finally, the empirical VVT model predicts mould risk on the indoor wall surface for the over-terrain part in autumn and summer for the under-terrain part.
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Wavelet Transform of Gravity Time Series in Hurbánovo
Pénzešová, Laura
The Hurbanovo Observatory has been part of the International Geodynamics and Earth Tide Service (IGETS) since 2021 and provides measurements utilizing the gPhoneX108 spring gravimeter. In this study, a wavelet decomposition using multiple types of wavelets was performed on the gravity time series with a 1-minute step. The study was performed on the gravity measurements during the February 2023 earthquakes in Turkey and Syria. The primary objective was to eliminate the influence of seismic events in the gravity time series using wavelet transform, aiming to find a balance between maintaining long-period signal components and minimising distortion of the original signal.
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Measurement of Changes of Stiffness Due to Saturation on Crushed Gravel Made from Weak Rock
Havlíček, Jaroslav ; Chalmovský, Juraj
Crushed gravel derived from weak rocks can be susceptible to degradation of its material properties. Saturation of this gravel can lead to significant changes. This article focuses on the laboratory measurement of crushed claystone from Czech Republic under 1D compression conditions. The tests involved varying initial water content, and samples were saturated at specific loads. Parameters of interest included the vertical deformation of the sample and changes in stiffness during loading and due saturation of the sample. The measurements revealed, that the saturation of this crushed gravel has a significantly affects its stiffness, leading to high compaction of the loaded sample. This process could potentially have a substantial negative impact on ground construction using this material.
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Circular Representative Volume Element for Homogenization of Discrete Model of Concrete
Středulová, Monika ; Eliáš, Jan
The contribution presents initial results obtained by employing a circular representative volume element (RVE) for the homogenization of a discrete model of concrete. Based on initial research, circular RVE might be a promising alternative to the classical square one (for 2D problems), especially considering its use in conjunction with periodic boundary conditions after strain localization in the material. The contribution shows the behaviour of the circular RVE in elastic loading and compares it to the results obtained by the usually used square RVE.
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