Search

Your search keyword '"Pakrastins, Leonids"' showing total 100 results
Start Over Author "Pakrastins, Leonids"
100 results on '"Pakrastins, Leonids"'

1. Modal Analysis of a Multi-storey Frame Building with Consideration of the Soil Base

Author

Kovrova, Viktoriia, Volkova, Viktoriia, Pakrastins, Leonids, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Cui, Zhen-Dong, Series Editor, Barros, Joaquim A. O., editor, Kaklauskas, Gintaris, editor, and Zavadskas, Edmundas K., editor

Published
2024
Full Text
View/download PDF

3. The impact of vibration on buildings: Problems and solutions

Author

Kovrova Viktoriia, Volkova Viktoriia, and Pakrastins Leonids

Subjects
Environmental sciences, GE1-350
Abstract

The article presents a comprehensive overview of a study investigating the influence of soil-foundation interaction on the natural frequencies and vibration safety of reinforced concrete cellular and frame buildings. Through numerical modelling and analysis, the researchers investigate the relationship between structural modes and soil-induced vibrations, emphasizing the sensitivity of vibration frequencies to soil composition. Findings reveal that alterations in foundation conditions can significantly affect building dynamics, particularly in mid-rise structures, highlighting the importance of targeted monitoring for early detection of potential issues. Furthermore, the study discusses the implications of vibrations on human comfort and safety, underscoring the need for effective vibration mitigation strategies. Various damping systems, including hydraulic, dry friction, and dynamic dampers, are proposed as practical solutions to minimize the adverse effects of vibrations on both structures and occupants. Overall, the study underscores the critical role of vibration safety in ensuring the resilience and well-being of buildings and their inhabitants.

Published
2024
Full Text
View/download PDF

6. The Impact of Aggregates Type to Abrasion Resistance of Mortar

Author

Makaronichev, Andrey, Belyaeva, Svetlana, Pakrastins, Leonids, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Anatolijs, Borodinecs, editor, Nikolai, Vatin, editor, and Vitalii, Sergeev, editor

Published
2020
Full Text
View/download PDF

7. Structural health monitoring by merging dynamic response data

Author

Gaile Liga, Pakrastins Leonids, and Ratnika Lasma

Subjects
structural health monitoring, modal analysis, damage detection, finite element method, dynamic response, natural frequencies, structural analysis, temperature, vibration analysis, structural dynamics, buildings, Engineering (General). Civil engineering (General), TA1-2040
Abstract

The process of Structural Health Monitoring aims to detect changes in material and/or geometric properties, boundary conditions or member connectivity of a structural system in time. However, the transfer of research results into engineering practice poses several challenges, especially for stiff structures with very diverse geometry that could not be well dynamically exited like low and medium-rise structures under ambient vibration conditions. Noise in modal parameters from output-only modal analysis due to variable environmental and operational conditions is considered one of the most problematic aspects of detecting structural damage using a vibration-based method. This research proposes a new way to reduce environmental noise in vibration data and dynamic parameters by merging dynamic response data from two similar shear wall buildings. The object of the study is a three-story reinforced concrete building. First, the damage features as natural frequencies and zero-order temporal moment of the vibration response are studied. Further, those feature changes are explored by means of modelling wall removal/opening introduction into the finite element models. It is established that the variation in the base excitation spectrum has more impact on dynamic response than introduced structural changes. Therefore, a time-domain feature like a zero-order temporal moment of the vibration response is not applicable for the proposed method. The appropriate damage sensitive feature vector for this approach is the difference of natural frequencies from two monitored buildings. The proposed method for fusion of vibration information from several buildings that share the same environmental and operational conditions filter out environmental noise effectively and give a clear advantage in reducing false alarm possibility during continuous and automated structural health monitoring process.

Published
2022
Full Text
View/download PDF

8. Long-term properties of cement mortar under compression, tension, and 3-point bending

Author

Sprince Andina, Gailitis Rihards, Pakrastins Leonids, Kozlovskis Tomass, and Vatin Nikolai

Subjects
long-term properties, creep, shrinkage, compression, tension, 3-point bending, digital image correlation, pva fibre, opc mortar, Engineering (General). Civil engineering (General), TA1-2040
Abstract

Cement composite long-term property assessment usually is limited to the compression strain state due to the difficulty of performing long-term tests in tension and 3-point bending. This paper shows the difference in long-term properties in compression, tension, and 3-point bending for plain ordinary Portland cement mortar (OPC). The obtained results were compared to reinforced specimen results to determine whether the PVA refibres improve the long-term properties of OPC mortar in various stress-strain conditions. Cylinders, compact tension specimens (CT), and beams – plates were prepared to evaluate material properties and the role of fibre reinforcement in these different stress states. Additionally, to conventional surface-attached strain gauges, 2D-DIC was employed to observe the creep strain of specimens in tension. This paper aim to determine long-term property differences in compression, tension and 3-point bending and, also, to see if low amount PVA fibre incorporation improve long-term properties in previously stated stress-strain states. It was determined that the usage of 1 % of PVA fibres increases creep strains in compression on average by 15 % and reduced by 7 % in tension. It reduces shrinkage strain by 18 % in compression and 8 % in tension. The long-term deflection for the PVA fibre-reinforced specimens are, on average by 55 % higher than for plain OPC mortar specimens in 3-point bending.

Published
2021
Full Text
View/download PDF

9. Ultimate load capacity of high-performance fibre-concrete hollow square columns

Author

Buka-Vaivade Karina, Serdjuks Dmitrijs, Sliseris Janis, Pakrastins Leonids, and Vatin Nikolai

Subjects
high-performance fibre-reinforced concrete, hollow square section, hollow concrete column, finite element method, response surface method, eccentric loading, computational time reduction, simplified analytical calculation, Engineering (General). Civil engineering (General), TA1-2040
Abstract

High-performance fibre-reinforced concrete is gaining popularity due to fibres ability to improve the poor properties of high-performance concrete. High-performance materials make using of thin-wall structures possible. Square section with square hollow provides decreasing of non-renewable material consumption, column’s high stiffness in the both planes and possibility to integrate the engineering communication inside of columns. The current study focuses on the development of analytical simplified calculation method that approximate output results of finite elements calculations for columns under eccentric loading with complicate hollow square-section. Analytical simplified calculation method to determine column’s load-carrying capacity is developed as the second-degree polynomial equation which is based on response surface method. The variables of equation are column height and material consumptions of the high-performance fibre reinforced concrete and steel of the additional longitudinal reinforcement. Data set of 27 experiments calculations was used to get the coefficients of adequate equation. Based on the results, the obtained equation makes it possible to predict the load-carrying capacity of the column in selected the factors interval on which a function was defined with sufficient precision. The difference between load-carrying capacities determine by numerical model based on the finite element method and by obtained second-degree equation does not exceeds 3.3%.

Published
2021
Full Text
View/download PDF

16. Cyclic Load Impact Assessment of Long-Term Properties in Compression to Steel and Polyvinyl Alcohol Fibre-Reinforced Geopolymer Composites.

Author

Gailitis, Rihards, Sprince, Andina, Łach, Michał, Gavrilovs, Pavels, and Pakrastins, Leonids

Subjects
CYCLIC loads, IMPACT loads, FIBROUS composites, STRAINS & stresses (Mechanics), VALUATION of real property, COMPRESSION loads, POLYVINYL alcohol
Abstract

This study investigates the cyclic load application impact on fly-ash-based geopolymer composites that are reinforced with a low amount of fibre reinforcement. For reinforcement purposes, polyvinyl alcohol and steel fibres are used. For testing purposes, four geopolymer composite mixes were made, three of which had fibre reinforcement. Simultaneously, specimens were tested for shrinkage, static-load-induced creep, and cyclic-load-induced creep. For static and cyclic creep testing, specimens were loaded with 20% of their strength. For cyclic creep testing, load application and release cycles were seven days long. When each cycle was introduced, the load was applied in steps. Necessary load application or unloading lasted for 5 min and consisted of four steps, each 25% of the necessary load. From the long-term static and cyclic creep tests, it was seen that only the plain specimens showed that static creep strains are within cyclic creep strains. For all the other specimens, the static load was higher than the cyclic-load-induced creep amplitude. Also, 1% polyvinyl alcohol fibre-reinforced specimens showed the most elastic characteristics under cyclic load, and 1% steel fibre-reinforced specimens appeared to be the most resistant to the cyclic load introduction. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

17. Potential Use of Construction Waste for the Production of Geopolymers: A Review †.

Author

Radina, Liga, Sprince, Andina, Pakrastins, Leonids, Gailitis, Rihards, and Sakale, Gita

Subjects
FIBERS, SELENIUM poisoning, POLYMERS, CONCRETE, CEMENT
Abstract

In recent decades, geopolymer concrete has often been viewed as an alternative to traditional concrete. Although its comparatively lower production of greenhouse gas emissions during a lifecycle is usually mentioned at the top of the list of benefits, the possibility of using various waste materials in its production is a clear advantage as well. This literature review summarizes and analyses the existing information on the different available construction wastes for the production of geopolymer and foamed geopolymer concrete and analyzes the curing conditions, constituents in the aluminosilicate precursor, mechanical properties, and the activator type. As part of the literature review, the use of autoclaved aerated concrete and brick wastes has been evaluated. Autoclaved concrete has been chosen because it is a typical low-strength, cement-based construction material and demolition waste that is currently disposed of in landfills, making it quite a challenge for direct use as a supplementary cementitious material. On the other hand, brick waste, one of the most common construction wastes, can be feasibly used in the form of brick dust. This literature review uses data from randomly selected studies. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

31. Long-term properties of foamed concrete

Author

Gailitis, Rihards, primary, Sprince, Andina, additional, Pakrastins, Leonids, additional, Shakhmenko, Genadijs, additional, Kozlovskis, Tomass, additional, and Radina, Liga, additional

Published
2019
Full Text
View/download PDF

32. Heat release and thermal conductivity of expanded-clay concrete for 3D printer

Author

Usanova, Kseniia, Barabanshchikov, Yuriy, Pakrastins, Leonids, Akimov, Stanislav, and Belyaeva, Svetlana

Subjects
cement, heat of hydration, silica fume, thermal transmittance, expanded-clay concrete, permeability of heat, regression analysis, 3d printer, superplasticizer, lcsh:TA1-2040, heat release, thermal conductivity, furnace slag, lcsh:Engineering (General). Civil engineering (General), claydite concrete
Abstract

The subject of research is expanded-clay concrete with additives of ground granulated blast-furnace slag, silica fume, superplasticizer admixture and air-entraining admixture for 3D printing. The heat release of concrete and thermal conductivity of concrete are investigated depending on the concrete composition (cement, water cement ratio, expanded-clay), additives (slag, silica fume) and admixtures (superplasticizer, air-entraining agent). The thermal conductivity of concrete depends primarily on the expanded clay gravel content and depends less on the cement content. If both factors increase, the thermal conductivity decreases. This is due to the replacement of dense sand grains with a more porous cement paste. The influence of air-entraining admixture on the thermal conductivity of expanded-clay concrete was not detected due to the high scattering of the experimental points. It was confirmed that the cement content and water cement ratio have an impact on the integral value of the heat release per unit mass of cement (q = Q/C). This value decreases with increasing cement content. The reason for this is that the total heat generated by concrete Q, with constant W/C and other equal conditions, increases linearly with increasing the cement content. The air-entraining admixture increases the heat generation by concrete. This is due to the chemical interaction between the admixture and cement hydration products with the formation of thermodynamically more stable compounds.

Published
2021

34. Long-term properties of foamed concrete.

Author

Gailitis, Rihards, Sprince, Andina, Pakrastins, Leonids, and Shakhmenko, Genadijs

Subjects
CONSTRUCTION materials, CONCRETE, BLOCKS (Building materials), COMPRESSIVE strength, ELASTICITY
Abstract

Foamed concrete has been used as a building material since the early 1920s. In the beginning, it was used as an insulation material with very low density. Since then there have been attempts to improve the structural properties in order to increase materials load-bearing capacity. In the present-day foamed concrete is being used in soil reinforcement, manufacturing of building blocks and other sorts of construction materials (Mugahed Amran, Farzadnia, & Abang Ali, 2015). The aim of this article is to determine the behaviour and long-term properties of foamed concrete. Cylindrical specimens (Ø46×190 mm) were used for creep and shrinkage testing. The creep properties of the specimens were determined by loading them with 20% and 60% of the ultimate compressive stress value (Sprince, 2015). The compressive strength, creep, shrinkage and specific creep of the material were examined. It was determined that during 90 days of creep testing the non-linear creep deformations (specimens loaded with 60% of the ultimate stress) are 4 times larger than linear creep deformations (specimens loaded with 20% of the ultimate stress). Also, changes in the modulus of elasticity of foamed concrete were researched over time. Foamed concrete modulus of elasticity reached 12.21 GPa on the 28th day, 12.49 GPa on the 62nd and 14.23 GPa on the 144th day since the specimens were made. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

37. Overcoming Problems with Waste Water Treatment from Dense Emulsions in the Oil Refining Industry

Author

Mikryukova, E. M., Suvorova, E. V., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

38. Fibre-Reinforced Bored Electric Discharge Technology Pile as a Buried Reinforced Concrete Structure

Author

Fedorov, P. Yu., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

39. Designing the Organization of Buildings and Structures Construction in Special Natural and Climatic Conditions

Author

Bogdanov, Vasily Filippovich, Sokolova, Alina Iosifovna, Petrova, Irina Vladimirovna, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

40. Deep Earth Anchor ERT

Author

Sokolov, N. S., Fedorov, P. Yu., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

41. Optimum Type of Depth Constructions in Insulated Soils

Author

Sokolov, N. S., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

42. Rigidity of Supporting Sections of High Building Bars and the Possibility of Its Monitoring by Inclinometers

Author

Plotnikov, Alexey N., Ivanov, Mikhail Yurievich, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

43. More About the Possibilities of the ERT Injection Piles

Author

Sokolov, N. S., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

44. Optimum Type of Depth Reinforced Concrete Structures When Strengthening the Foundation of Industrial Buildings

Author

Sokolov, Nikolay Sergeevich, Viktorova, Svetlana Stanislavovna, Alekseeva, Galina Nikolaevna, Terekhova, Olga Pavlovna, Malyanova, Lydia Ivanovna, Maguskin, Victor Vladimirovich, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

45. Tamped Slotted Foundations

Author

Glushkov, Alexey, Glushkov, Vyacheslav, Glushkov, Ilya, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

46. Migrating Corrosion Inhibitor (MCI) for Concrete Rebar and Its Inhibitory Efficiency

Author

Leonovich, Sergei N., Karpushenkava, L. S., Karpushenkov, S. A., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

47. The Issues of Reliability of Microclimate Creation Systems

Author

Rusinova, N. G., Fedorov, N. A., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

48. Development, Strength Check, Calculation of the Wind Load of a Multi-layer Guarding Structure

Author

Bakhmisova, M. A., Plotnikov, Alexey N., Sakmarova, L. A., Petrov, M. V., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

49. The Use of Carbon Fiber Tapes as One of the Ways to Increase the Seismic Resistance of Gas-Silicate Walls

Author

Dzhamuev, B. K., Erizhokova, E. S., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

50. Energy Efficiency and Sustainability of High-Rise Buildings and Structures

Author

Malyanova, Lydia Ivanovna, Sergeeva, Maria Alekseevna, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Vatin, Nikolai I., editor, Tamrazyan, Ashot G., editor, Plotnikov, Alexey N., editor, Leonovich, Sergei N., editor, Pakrastins, Leonids, editor, and Rakhmonzoda, Ahmadjon, editor

Published
2022
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results