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1

Crack resistance of RC columns strengthened by CFRP under 30% of uls loading

Blikharskyy Yaroslav, Khmil Roman, Selejdak Jacek, Katunský Dušan, Tytarenko Roman, Blikharskyy Zinoviy

System Safety : Human - Technical Facility - Environment

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2023

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Vol. 5, iss. 1

36--45

EN

Nowadays, among many existing reinforced concrete (RC) columns, it is impossible to find samples that work only as centrally compressed members – their vast majority work as eccentrically compressed members. On the other hand, the significant volumes of reconstruction in Ukraine will require studies of the work of various RC structures strengthened under different load levels. In addition to choosing the method of strengthening itself, the relevant tasks will be studies of bearing capacity, crack resistance, reliability (including residual resource) of structures, etc. This article presents the method of crack resistance experimental study of eccentrically compressed RC members. The proposed method was tested on unstrengthened (ordinary) and strengthened (in a stretched zone) RC columns; the results of experimental studies for ordinary and strengthened samples were also obtained. The columns were strengthened with a composite material (from many carbon-fiber-reinforced polymers) – the Sika Carbodur S512 strip. The feature of the crack resistance study of columns was that they were strengthened under the initial load level of 30 %. As a result of experimental research on the samples strengthened under load, we stated that the width of the crack decreased on average by about 36 % (at the comparable values of the active load). In turn, the average maximum length of cracks decreased to about 50 % of the height of the cross-section (for unstrengthened samples, this value was approximately 80 %), and the eccentric compressive ultimate load was increased by about 33 %.

2

Ocena nowoczesności prasy próżniowej wykorzystywanej w procesie wytwarzania cegieł ceramicznych

Selejdak Jacek

Przegląd Budowlany

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2023

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R. 94, nr 9-10

140--143

PL

Nowoczesność maszyn i urządzeń stosowanych w procesach wytwarzania w istotny sposób wpływa na kształtowanie jakości wyrobów. W artykule przeprowadzona została analiza nowoczesności prasy próżniowej wykorzystywanej w procesie wytwarzania cegieł ceramicznych. Do oceny nowoczesności prasy wykorzystano pięciostopniową skalę Parkera. Poszczególne części podzespołów urządzenia zakwalifikowane zostały do odpowiednich kategorii, a następnie sklasyfikowano je na odpowiednim poziomie skali Parkera. Na podstawie przeprowadzonej oceny stwierdzono, że analizowane urządzenie ogólnie można sklasyfikować na 4 poziomie skali Parkera, co oznacza, że jest to urządzenie nowoczesne.

EN

The modernity of machinery and equipment used in manufacturing processes has a significant impact on shaping the quality of products. In the paper, the modernity of the vacuum press used in the ceramic brick manufacturing process was analysed. The Parker’s five-point scale was used to assess the modernity of the press. Individual parts of the subassemblies of the device have been classified into appropriate categories, and then classified at the proper level of the Parker’s scale. On the basis of the assessment, it was concluded that the analysed device could generally be classified at 4th level of the Parker’s scale, which means that it is the modern device.

3

Mathematical modelling of stress-strain state of steel-concrete beams with combined reinforcemenent

Selejdak Jacek, Bobalo Taras, Blikharskyy Yaroslav, Dankevych Iryna

Production Engineering Archives

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2023

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Vol. 29, Iss. 1

108--115

EN

Most of the modern computer software for the building structures` calculation is based on mathematical dependencies which make it possible to analyse rather complex stress-strain state of structures subjected to loading. As a rule, the calculation is based on the finite element method and is reduced to the calculation of deformations arising in structures due to the action of external forces with the use of real strain diagrams of materials, σ-ε diagrams for concrete and reinforcement. Modern normative regulations for reinforced concrete structures` calculation are also based on the deformation model using material deformation diagrams, which are as close to the real ones, as possible. Therefore, this study was aimed to investigate in more detail the stress-strain state and the physical essence of the processes occurring in reinforced concrete structures with combined reinforcement according to mathematical approaches and regulations of DBN B.2.6-98:2009 and DSTU B. In 2.6-156:2010. Namely, in the research is analysed the combined reinforcement of S245 steel tapes and A1000 rebar, which is used in the production of reinforced concrete elements. The results of mathematical modelling were compared with the calculation results, according to DBN B.2.6-98: 2009 and DSTU B. B 2.6-156:2010, as well as with field experimental data. Therefore, the conclusion could be made, whether it is possible to use this technique with sufficient accuracy to calculate reinforced concrete structures with combined reinforcement.

4

Wpływ wybranych czynników na dokładność oceny zbrojenia płyt żelbetowych metodą elektromagnetyczną

Ordon-Beska Beata, Selejdak Jacek

Materiały Budowlane

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2023

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nr 11

1--5

PL

W artykule przedstawiono wyniki badań elektromagnetycznych kilku modeli zbrojenia ortogonalnego z zastosowaniem Profometru PM-650. Oceniono powtarzalność pomiarów w przypadku różnego usytuowania tzw. ośrodka pomiaru względem pręta poprzecznego i oszacowano wartości błędów pomiarowych. Stwierdzono, że pozycja skanera istotnie wpływa na pomiar średnicy, natomiast w mniejszym stopniu na pomiar otuliny. W artykule poruszono również problem wpływu na wyniki czynników zaburzających pole elektromagnetyczne. W efekcie przeprowadzonych badań sformułowano zalecenia praktyczne.

EN

The article presents the results of electromagnetic research of several models of orthogonal reinforcement. Profometer PM-650 was used. The repeatability of measurements for different locations of the so-called measurement centre relative to the transverse member was evaluated and the values of measurement errors were estimated. It was found that the position of the scanner significantly affects the measurement of the diameter, while the measurement of the coating affects to a lesser extent. The article also discusses the problem of influencing the results of electromagnetic field disruptors. Practical recommendations were formulated.

5

The effect of air-entraining agent on the properties of mortars

Blikharskyy Zinoviy, Markiv Taras, Sobol Khrystyna, Turba Yurii, Selejdak Jacek

Archives of Civil Engineering

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2023

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Vol. 69, nr 3

147--156

EN

The effect of the air-entraining agent on properties of mortar mixtures as well as on the compressive strength of hardened mortars was the objective of this study. Such mortars contain a certain amount of evenly spread closed air-voids pores with dimensions of 0.02-0.05 mm. On the one hand, the presence of a large volume of such air bubbles results in the reduction of mechanical properties of mortar. On the other hand, the use of this technological approach improves rheological properties of mortar mixture. The effect of the air entrainment on the flow, density, volume of entrained air of mortar mixture and compressive strength of hardened mortar was established. Obtained results show substantial increasing in the mortar flow at cement to sand ratio 1:2 by 1.8 times. The further decrease of C:S ratio results in a slight increase of the flow and even negligible its decrease at C:S = 1:4 compared to the reference mortar. The increase of the volume of entrained air results in the decrease of the density and compressive strength of mortar, but improve the resistance to freezing/thawing cycles. The results of this study can be a guide for mortar mix design to choose the most appropriate mix proportion to produce economically efficient mortars.

PL

Celem badań był wpływ domieszki napowietrzającej na właściwości mieszanek zaprawowych oraz wytrzymałość na ściskanie zapraw. Zaprawy takie zawierają pewną ilość równomierne rozprowadzonych, zamkniętych porów powietrznych o wymiarach 0,02-0,05 mm. Z jednej strony, obecność dużej ilości takich pęcherzyków powietrza powoduje obniżenie właściwości mechanicznych zaprawy. Z drugiej strony, zastosowanie tego podejścia technologicznego poprawia właściwości reologiczne mieszanki zaprawy. Określono wpływ domieszki napowietrzającej na urabialność, gęstość, objętość wprowadzonego powietrza oraz wytrzymałość na ściskanie zaprawy. Uzyskane wyniki wskazują na znaczny, 1,8-krotny wzrost rozpływu zaprawy przy stosunku cementu do piasku 1:2. Dalsze zmniejszanie stosunku C:S powoduje niewielki wzrost urabialności, a nawet znikomy jego spadek przy C:S = 1:4 w porównaniu do zaprawy wzorcowej. Wzrost objętości wprowadzonego powietrza powoduje zmniejszenie gęstości i wytrzymałości na ściskanie zaprawy, ale poprawia mrozoodporność. Wyniki badań mogą być wskazówką przy projektowaniu zapraw, aby wybrać najbardziej odpowiednie proporcje mieszanki w celu wytworzenia ekonomicznie efektywnych zapraw.

6

Specifics of physico-mechanical characteristics of thermally-hardened rebar

Kopiika Nadiia, Selejdak Jacek, Blikharskyy Yaroslav

Production Engineering Archives

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2022

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Vol. 28, Iss. 1

73--81

EN

Thermal hardening is widely used nowadays for modification of steel bar properties and obtaining effective reinforcing material. Strength and deformation characteristics of thermally hardened reinforcement is the complex indicator of reinforcement efficiency. Therefore, reliable assessment of physico-mechanical characteristics of thermally hardened rebar is topical and important issue. This article is intended to the analysis of physico-mechanical characteristics of thermally hardened rebar on the basis of experimental data. Thorough statistical processing of experimental data was made and specific features of strength parameters were identified. Analytical model of strength characteristics is proposed, which enables to take into account inhomogeneous strength properties of the rebar along its cross-section. It could be stated that assessment of physico-mechanical characteristics of thermally hardened rebar is topical and important issue, which is the prospective area of further research.

7

Modelling of strengthening of concrete beams with FRP in Ansys software

Kowalski Damian, Selejdak Jacek

Materiały Budowlane

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2022

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nr 11

188--191

EN

The purpose of this article is to confirm an accuracy of Cohesive Zone Model (CZM) implemented in Ansys for modelling concrete beams strengthened with fiber reinforced polymer (FRP) tapes. Only mode II of debonding was taken into account, which is sufficient for a case of bent beam strengthened with FRP tape glued to its bottom. Results show satisfying coincidence of used model with experimental data and therefore confirm usefulness of CZM for solving the above mentioned problems.

PL

Celem artykułu jest weryfikacja dokładności modelu Cohesive Zone Model (CZM), zaimplementowanego w programie Ansys, w modelowaniu numerycznym belek żelbetowych wzmacnianych taśmami z polimerów zbrojonych włóknami (FRP). Wzięto pod uwagę jedynie postać II utraty przyczepności, co jest wystarczające w przypadku belek zginanych wzmocnionych taśmą przyklejoną do ich spodu. Wyniki pokazują zadowalającą zgodność użytego modelu z danymi eksperymentalnymi i tym samym potwierdzają użyteczność CZM do rozwiązywania ww. zagadnień.

8

Influence of the percentage of reinforcement by un-stressed rebar on the deformability of pre-stressed RC beams

Blikharskyy Yaroslav, Selejdak Jacek, Bobalo Taras, Khmil Roman, Volynets Myhailo

Production Engineering Archives

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2021

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Vol. 27, Iss. 3

212--216

EN

This article presents the materials of deformability studies of pre-stressed steel-concrete beams reinforced with a package of reinforcement with different ratio of tape and rebar in the pure bending moment zone. The aim of the research was determination of the reinforcement percentage influence, for pre-stressed reinforced concrete beams reinforced with a package of reinforcement on their deformability. Also, the aim was to evaluate the effectiveness of using pre-stressed rebar in combined reinforcement. The practical significance of the experimental research is to study the deformability in pre-stressed bending elements with external tape and rebar reinforcement, taking into account the influence of different ratios of reinforcement areas within the combined reinforcement and development of proposals for such structures` calculation and design. The scientific novelty of the research is in obtaining the deformability characteristics of reinforced concrete beams reinforced with a package of reinforcement (tape and steel bars with periodic profile) with different ratios in the case of static loads` action.

9

Influence of the percentage of reinforcement damage on the bearing-capacity of RC beams

Blikharskyy Yaroslav, Selejdak Jacek

Budownictwo o Zoptymalizowanym Potencjale Energetycznym

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2021

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Vol. 10 Nr 1

145--150

EN

This article presents the test results of reinforced concrete beams with different percentages of reinforcement damage. One of the main causes of structural damage is corrosion. The main cause of corrosion is an aggressive environment, which can endanger the environmental ecology. During the study, the effect of damage to reinforced concrete beams was investigated. The beams were produced full-sized, 100x200x2100 mm. According to the research program, 6 beams were tested, including undamaged control samples with a single reinforcement bar of ∅20 mm - BC-1 and BC-2; samples with a reinforcement bar of ∅20 mm with about 10% damage - BD-3 and BD-4; samples with a reinforcement bar of ∅20 mm with about 20% damage - BD-5 and BD-6. The reinforcement bar was damaged before concreting the samples. As a result, it was determined that a reduction in the bearing-capacity of the reinforced concrete beams depended on the percentage of damage to the reinforcement bar.

10

Comparison of calculation methods for sheet piling

Kosmala-Kot Wiesława, Selejdak Jacek

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2020

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Z. 26 (176)

89-94

EN

Basic methods for calculating sheet piling were presented in the paper. The Blum’s graphical and analytical-graphical methods were characterized for a sheet pile that is single anchored at the top and freely supported at the bottom. Methods for determining the sheet pile length, sinkage into the soil and the selection of the sheet pile profile were shown. The method for determining the reaction value on the sheet pile support was also presented. The calculated design parameters for both methods were compared in a table. On the basis of the above calculations, it was determined that the two calculation methods lead to similar cross-sections of sheet piling.

PL

W artykule przedstawiono podstawowe metody obliczania ścianek szczelnych. Scharakteryzowano metody graficzno-analityczną i analityczną Bluma dla ścianki szczelnej górą jednokrotnie zakotwionej zaś dołem swobodnie podpartej. Pokazano sposób określania długości ścianki, potrzebnego zagłębienia w gruncie oraz doboru profilu ścianki. Ponadto zaprezentowano również metodę wyznaczenia wartości reakcji na podporze ścianki. Wyliczone parametry projektowe dla obu metod zestawiono w tabeli. Na podstawie przeprowadzonych obliczeń stwierdzono. że zastosowane dwie metody obliczeniowe prowadzą do otrzymania zbliżonych przekrojów ścianek szczelnych.

11

Determination of the optimum percentage of high strength bars in RC beams with combined reinforcement using FEM

Selejdak Jacek, Blikharskyy Yaroslav, Bobalo Taras, Kopiika Nadiia

System Safety : Human - Technical Facility - Environment

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2020

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Vol. 2, nr 1

230--236

EN

In this work on the basis of the developed and tested mathematical model, the numerical experiment is conducted in order to study in more detail the specifics of performance of concrete beams` with combined reinforcement. For this purpose nine series of reinforced concrete beams with different combination of steel bars (A400C, At800, A1000) and ribbon reinforcement (C275) were modeled. In the developed series two classes of concrete were used: C50/60, C35/45. The functions derived on the basis of mathematical modeling allow us to determine the recommended percentage of high-strength reinforcement of common reinforced concrete structures with single reinforcement. Therefore, the possibility is obtained to reduce the total structures` reinforcement percentage, increasing their deformability by the specified value without affecting the bearing capacity.

12

Non-uniform corrosion of steel rebar and its influence on reinforced concrete elements` reliability

Blikharskyy Yaroslav, Kopiika Nadiia, Selejdak Jacek

Production Engineering Archives

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2020

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Vol. 26, Iss. 2

67--72

EN

Remarkable place of reinforced concrete structures in construction field has been noted in wide number of recent researches. Subsequently, their degradation due to aggressive environment has become the topical problem nowadays. Therefore, the formulation of reliable technique for corroded element strength decrement is of great importance, and could be achieved only with the use of complex experimental and theoretical analysis. In this article an attempt is made to propose the mathematical approach to corrosive process modelling, taking into consideration the specifics of its development. According to thorough literature review on existing studies, main specifics of the process were indicated for further suppositions and assumptions formulation. Accordingly, the complex theoretical investigation with corresponding mathematical computations was conducted and results of analytical modelling were discussed. As the initial data for analytical modelling results of previously conducted experiments were used. Analysis of the obtained results shows rather high correspondence with the real conditions of structural element exploitation, taking into consideration material anisotropy and complexity of the corroded zone spread along the rebar cross-section. Proposed methodology for limit force decrease evaluation in general demonstrates reliable results and could be used for further evaluation of corrosion impacts on reinforced concrete elements bearing capacity.

13

Safety of formworks in the engineering and general construction sector

Brózda Kinga, Selejdak Jacek

System Safety : Human - Technical Facility - Environment

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2019

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Vol. 1, nr 1

284--290

EN

Formwork systems are necessarily used in the implementation of the RC (reinforced concrete) structures. Formworks are required regardless of whether a construction is monolithic or prefabricated and used to form the engineering and general structures or structural elements, such as abutments, supports and decks of the bridges, tanks and retaining walls, but also industrial and accommodation facilities etc. Ensuring the OHS (occupational health and safety) during transport, assembly and disassembly of formworks is a necessary condition for the execution of RC works in a safe and economical way. The paper presents the analysis of the safety requirements for formworks. Furthermore, the general requirements for the execution of the formwork structures were discussed. The most common organizational and technological mistakes and cased of neglects related to the operation of the formwork which lead to infringement of the OHS regulations were also identified.

14

Corrosion of reinforce bars in RC constructions

Blikharskyy Zinoviy, Selejdak Jacek, Blikharskyy Yaroslav, Khmil Roman

System Safety : Human - Technical Facility - Environment

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2019

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Vol. 1, nr 1

277-283

EN

In this article presented results of researching corrosion of steel bars in aggressive environment in time under loading. For researching were used special equipment. The experience and research works shown that steel bars in the crack cross-section area can be corrode. With increasing width of crack in re-bars and power of aggressive of environment increased the level of corrosion and decreased time of progress. The level of danger of corrosion in the crack in depend of specialty of steel bars. It is geometry parameters of steel bars and characteristic of corrosive behaviour. The general tendency of the influence of various defects on the strength of steels is widely studied experimentally and theoretically only for geometrically correct stress concentrators. For damages that are irregular in shape, such as corrosion ulcers, significantly less researching in each case must experiment to find their effect on the mechanical properties of steels. In this work the influence of simultaneous action of the aggressive environment and loading on strength of steel rebars has been described.

15

Weight minimization of spatial trusses with genetic algorithm

Grzywiński Maksym, Selejdak Jacek

Quality Production Improvement - QPI

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2019

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Vol. 1, Iss. 1

238--243

EN

A genetic algorithm is proposed to solve the weight minimization problem of spatial truss structures considering size and shape design variables. A very recently developed metaheuristic method called JAYA algorithm (JA) is implemented in this study for optimization of truss structures. The main feature of JA is that it does not require setting algorithm specific parameters. The algorithm has a very simple formulation where the basic idea is to approach the best solution and escape from the worst solution. Analyses of structures are performed by a finite element code in MATLAB. The effectiveness of JA algorithm is demonstrated through benchmark spatial truss 39-bar, and compare with results in references.

16

Assessment of the effect of the pre-cast beams IG axial spacing on the effort bridge span

Gąćkowski Roman, Selejdak Jacek

Quality Production Improvement - QPI

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2019

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Vol. 1, Iss. 1

281--288

EN

In designing of reinforced concrete bridges are often used pre-cast of pre-tensioned or post-tensioned prestressed members. In professional practice, when designing bridge span pre-cast of pre-tensioned prestressed beams IG type, different axial beams spacing’s are used and they are joined by a reinforced concrete slab. The paper presents a comparative analysis of an influence of the axial spacing of IG type beams in the cross-section of the bridge, on the bridge span effort, using standards PN-85/S-10042 and PN-EN 1992-2:2010. The optimal axial spacing of precast IG type beams is presented, while maintaining the standard conditions of ULS (Ultimate Limit State). Such a solution has a positive impact on the costs of the entire project, significantly lowering the global investment cost.

17

Zastosowanie geosyntetyków do wzmacniania dróg leśnych

Selejdak Jacek, Urbański Mariusz

Materiały Budowlane

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2019

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nr 4

56--57

PL

W artykule przedstawiono wybrane rozwiązania poprawiające nośność dróg leśnych z wykorzystaniem nowoczesnych materiałów geosyntetycznych. Zwrócono uwagę na zalety tego rozwiązania, takie jak m.in. zmniejszenie kosztów. Zastosowanie geosyntetyków w konstrukcji dróg (nie tylko leśnych), ze względu na ich właściwości,wpływa pozytywnie na trwałość konstrukcji podczas eksploatacji m.in. przez wzmocnienie podłoża gruntowego.

EN

The article presents selected solutions increasing the load capacity of forest roads with the use of modern materials such as geosynthetics. Attention was paid to the advantages of using geosynetics to strengthen forest roads among which, among others you can distinguish the currently significant cost savings. Therefore, the use of geosynthetics in the construction of roads (not only forest), due to their properties, has a positive effect on the durability of their operation, among others by strengthening the ground.