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1

Data-driven prediction and normalization of mechanical properties in jute fiber-reinforced concrete

Ahmad Soran Abdrahman, Mustafa Rozhnw Omer, Saeed Diyar Arif, Nadir Asa Omed, Mahmood Hersh Hama Amin F

Structure and Environment

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2025

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Vol. 17, no. 3

113--126

EN

Using fiber in the concrete is one of the methods to improve its capacity for the load resisting especially for the bending and tensile loading, but this process has two challenges, the first one is the energy usage, the waste gas emission which produced in these fiber’s industry, while the second challenge is the increase in the solid waste materials in the land which is include natural plant fiber. The usage of natural fiber instead of these industrial fibers will have a double advantage. This article deals with investigating the effect of using jute fiber on the properties of concrete, also proposing statistical models to predict the compressive strength of concrete by collecting the experimental data from previous experimental work. By using three different models, including the quadrant support vector machine, Integration Linear, and squared exponential Gaussian, and using 80 experimental data points. Based on the obtained results between the proposed models to predict the compressive strength of concrete, SVM provides higher accuracy and efficiency compared to the other proposed models, when the value of the coefficient of determination is higher than the IL, and SEG by 10.98%, and 1.09% respectively.

PL

Zastosowanie włókien w betonie to jedna z metod poprawy jego wytrzymałości na obciążenia, zwłaszcza zginanie i rozciąganie. Proces ten wiąże się z dwoma wyzwaniami. Pierwszym z nich jest zużycie energii i emisja spalin powstających w przemyśle włókienniczym, a drugim - wzrost ilości odpadów stałych w glebie, w tym naturalnych włókien roślinnych. Zastosowanie włókien naturalnych zamiast włókien przemysłowych przyniesie podwójną korzyść. Niniejszy artykuł analizuje wpływ zastosowania włókien jutowych na właściwości betonu, proponując również modele statystyczne do przewidywania wytrzymałości betonu na ściskanie poprzez zebranie danych eksperymentalnych z poprzednich badań laboratoryjnych, z wykorzystaniem trzech różnych modeli, w tym kwadrantowej maszyny wektorów nośnych (SVM), interakcji liniowej (IL) i gaussowskiej radialnej funkcji bazowej (SEG), a także 80 punktów danych eksperymentalnych. Na podstawie uzyskanych wyników pomiędzy proponowanymi modelami przewidywania wytrzymałości betonu na ściskanie SVM zapewnia wyższą dokładność i wydajność w porównaniu z innymi proponowanymi modelami, podczas gdy wartość współczynnika determinacji jest wyższa niż w przypadku IL i SEG, odpowiednio o 10,98% i 1,09%.

2

Influence of steel fiber content on the frost resistance of steel fiber reinforced rubberized concrete in sulfate environment

Jiang Lei, Zhang Ming, Jing Jiahua

Archives of Civil Engineering

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2025

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Vol. 71, nr 3

355--368

EN

To evaluate the performance of steel fiber-reinforced rubber concrete (SFRRC) in a sulfate environment, a rapid freeze-thaw testing procedure was employed to assess the influence of steel fiber content on parameters such as mass, relative dynamic modulus of elasticity, compressive strength, and damage layer thickness (Hf) of SFRRC. The testing revealed the deterioration pattern of SFRRC in a sulfate erosion and freeze-thaw environment. Additionally, the mercury intrusion porosimetry technique was utilized to further investigate the pore structure characteristics of SFRRC with the goal of revealing the damage mechanism from a microscopic perspective. The results indicate that SFRRC undergoes a lower degree of freeze-thaw damage in sulfate solution than rubber concrete without steel fibers. The degree of deterioration of SFRRC gradually decreases with an increasing steel fiber content, but its frost resistance is adversely affected at a content level of 2.0%. The Hf can be used to characterize the internal damage in the SFRRC. As the Hf increases, the loss of compressive strength in the damage layer becomes more pronounced. A correlation exists between the compressive strength of SFRRC and that of the damage layer under sulfate erosion and freeze-thaw conditions, enabling calculation of the latter based on the compressive strength of the SFRRC under the influence of environmental factors. An appropriate incorporation of steel fibers optimizes the pore structure of SFRRC. As the steel fiber content gradually increases within a range of 0 to 1.5%, the total porosity decreases along with the total pore volume and area. This leads to an improvement in the pore structure of the SFRRC. At a content of 1.5%, the pore structure of SFRRC is optimized and its resistance to sulfate freeze-thaw performance is maximized.

3

A Set of Finite Elements for 2D Analysis of Reinforced Concrete Foundations on Deformable Subsoil

Szajna Waldemar

Civil and Environmental Engineering Reports

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2024

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Vol. 34, no. 2

100--116

EN

The paper presents a formulation and verification of a 2D soil – structure interaction model which enables the analysis of reinforced concrete shallow foundations under monotonic short-time loads. The structure supported by a deformable subsoil, whose elasto-plastic features are being considered. The structure model describes: the ability of crack creation, non-linear stress – strain characteristics of concrete and reinforcement and also reinforcement – concrete interaction. The foundation – subsoil contact model enables the identification of slide and adhesion zones. The presented mathematical formulation allowed for the development of a set of finite elements simulating the behaviour of the foundation, the subsoil and the contact zone between them. The elasto-plastic approach was used to describe the behaviour of the structure, the subsoil and the contact phenomena. Computer programs were prepared and verifying analyses were presented.

4

Utilizing ensemble learning in the classifications of ductile and brittle failure modes of UHPC strengthened RC members

Taffese Woubishet Zewdu, Zhu Yanping, Chen Genda

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 2

art. no. e86, 2024

EN

This study aims to achieve the swift and precise classification of ductile and brittle failure modes in flexural reinforced concrete (RC) members, specifically those with tension sides strengthened by ultrahigh performance concrete (UHPC). Employing six ensemble learning techniques - Bagging, Random Forest, AdaBoost, Gradient Boosting, XGBoost, and LightGBM - the authors utilize a comprehensive dataset comprising 14 features, which include manually labeled failure modes obtain from load-deflection curves. The model training spans four scenarios, varying in the inclusion or exclusion of features describing the cross-sectional area of RC members and moment resistance. XGBoost emerges as the most effective classifier, achieving an impressive 84% accuracy with high confidence. Additionally, the study employs the Shapley Additive Explanation (SHAP) technique on the best-performing model to illuminate the significance and impacts of various features in UHPC-strengthened flexural members’ failure modes. Notably, moment resistance and UHPC tensile strength surface as the most influential factors in predicting failure modes. Increased rebar yield strength, UHPC compressive strength, UHPC reinforcement ratio, and steel fiber volume in UHPC contribute to enhanced ductility in flexural members, while heightened moment resistance and UHPC layer thickness, along with a robust RC-UHPC interface, tend to induce brittleness. The introduction of such an effective failure modes classification model, coupled with the model’s explainability, instills trust in its predictions and facilitates seamless integration into real-world applications, particularly in seismic areas. The model’s ability to operate without the need for pre-experimental tests marks a significant advancement in the field.

5

Study on the tensile properties of basalt fiber reinforced concrete under impact: experimental and theoretical analysis

Xie Lei, Sun Xinjian, Yu Zhenpeng, Lian Huiheng

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 2

art. no. e99, 2024

EN

Basalt fiber (BF) can significantly improve the dynamic properties of concrete. However, the underlying mechanism of the effect on the dynamic splitting tensile properties of concrete by comprehensively considering BF content and BF length has not been fully clarified. Under such a background, this study aimed to carry out an orthogonal experiment on the dynamic splitting tensile properties of basalt fiber reinforced concrete (BFRC) by taking into account different fiber contents and lengths using the split Hopkinson pressure bar equipment. The research results indicate that addition of BF improves the dynamic splitting tensile strength and the integrity of concrete after failure. In addition, the sensitivity of the dynamic increase factor of concrete to strain rate shows a continuously increasing trend as BF content increases, but an upward trend first followed by a downward trend with the increase of BF length. Based on the combined results, the optimal fiber content and length were determined to be 0.2% and 6 mm, respectively. Then, combined with high-speed camera and scanning electron microscopy, the failure mechanism of BFRC was deeply revealed. It is found that the reinforcing effect of BF on concrete is mainly reflected as the pull-out failure at low strain rates and the pull-apart failure at high strain rates. Moreover, BF can change the development mode of cracks during the failure process by inhibiting the development of shear failure zone, thereby playing its cracking resistant role. Finally, the K&C model was modified based on the experimental data to make it adapt to BFRC.

6

Study of waterproof ability and corrosion resistance of basalt fiber‑reinforced concrete with superhydrophobic surfaces

Li Yunfeng, Wang Qing, Hou Chen, Song Qingnan, Zhang Rui, Wang Ning

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 2

art. no. e93, 2024

EN

Basalt fiber-reinforced concrete (BFRC) is used extensively in bridge engineering. However, seawater can cause the cracking of BFRC bridge concrete and the corrosion of steel reinforcement inside the concrete. In this study, an efficient fabrication method of the superhydrophobic surface of BFRC was used to improve its durability. BFRC has high surface compactness, and sodium stearate can play a better role as a modifier. Through the orthogonal study, superhydrophobic BFRC was prepared, and the effects of three major factors (temperature, time, and concentration) on the wettability of BFRC were investigated. The soaking time and solution concentration were more significant than any other factor. The capillary water absorption of the superhydrophobic BFRC was reduced compared to the BFRC. In addition, the soaking method could improve BFRC corrosion resistance by analyzing the equivalent circuit. The soaking method could improve the durability of BFRC effectively. Meanwhile, BFRC with a superhydrophobic surface had self-cleaning performance and good mechanical robustness. This research extends the scope and field of BFRC and provides technical support for utilizing the existing building.

7

Experimental investigation of RC shear walls with openings under cyclic loading repaired with externally bonded CFRP strips

Ozdemir Anil, Kopraman Yagmur

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 1

art. no. e14, 2024

EN

A total of 9 real scale reinforced concrete shear walls were produced, 3 of them being the reference, representing the basement floor of a reinforced concrete building. These 9 shear walls produced, 3 wall are fully filled, 3 of them have window openings and 3 of them have door openings. The RC shear walls were exposed to displacement-controlled reversed cyclic lateral loading. In the experiments that damaged the experimental specimens, loads up to 0.5% story drift ratio for moderate damage and 1.0% story drift ratio for heavy damage were applied. Within the scope of the experimental study, the damage distributions of the tested nine RC shear walls were examined in detail, and the strengthening technique was developed using CFRP strip and CFRP fan-type anchors. The performance of damaged RC shear walls after using the devised repair method was analysed. The study's findings revealed that the repair method created by employing CFRP strips to restore moderately damaged RC shear walls with and without apertures was well enough successful in restoring the shear walls' performance levels.

8

Experimental and theoretical study on the shear behavior of CFRP bar‑reinforced UHPFRC beams considering orientation and volume fraction of steel fibers

Liang Longming, Ke Lu, Feng Zheng, Li Chuanxi, Yan Banfu, Guo Jia

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 1

art. no. e1, 2024

EN

This paper aims to comprehensively understand the shear behavior of fiber-reinforced polymer (CFRP) bars reinforced ultra-high-performance fiber-reinforced concrete (UHPFRC) beams, and develop a calculation model to predict the shear capacity. The crucial parameters under consideration are the orientation and volume fraction of steel fibers. A magnetic field fiber orientation setup was utilized to achieve the desired orientation. The results indicated that all UHPFRC beams demonstrated shear failure, showing clear instances of both beam action and arch action throughout the failure progression. By orienting the steel fibers at an angle of 60° relative to the longitudinal axis of the beams, the average shear capacity increases by 23.51% compared to that of the beams with random distributed steel fibers because the steel fibers are almost perpendicular to the diagonal shear cracks. Increasing the fiber volume fraction from 1.5% to 2.0% led to a significant maximum increase in the average shear capacity, reaching 31.73%. Moreover, the larger orientation angles and higher volume fraction of steel fibers contributed to improved ductility, reaching a maximum of 124.0%. Finally, a highly accurate model based on the fiber-matrix discrete approach was formulated. The proposed model showed a slight overestimation of shear capacity, with most values not exceeding 10%, and a standard deviation below 6.22%.

9

Fibrobeton – kompozyt cementowy do zadań specjalnych

Dziedzic-Polańska Izabela

Izolacje

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2023

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T. 28, nr 2

52--57

PL

W artykule omówiono specyfikę fibrobetonu. Przedstawiono różnego rodzaju włókna do zbrojenia betonu. Opisano jego właściwości, a także wpływ zbrojenia betonu na optymalizację kosztów inwestycji.

EN

The article discusses the specificity of fibre concrete. Various types of fibres for concrete reinforcement are presented. Its properties as well as the impact of concrete reinforcement on the optimization of investment costs are described.

10

Analysis of the influence of electrical parameters of concrete and reinforcement inside concrete walls on the values of the electric field intensity

Choroszucho Agnieszka

Przegląd Elektrotechniczny

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2022

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R. 98, nr 8

111--117

EN

The aim of the article is to analyze the influence of the variability of the electrical parameters of non-ideal and absorbing dielectric (usual concrete) on the values of the electric field intensity. A detailed analysis was also made of the influence of the reinforcement diameter, the number of rows and the spacing between the bars on the values of the electric field intensity. The subject of the research was a model containing a loadbearing wall made of concrete (absorbing dielectric) with reinforcement in the form of steel rods (conductor). Four reinforcement systems commonly used in construction were analyzed. Additionally, the discussion covered the influence of electrical parameters (electric permittivity, conductivity) on the field intensity values calculated for heterogeneous, complex material structures. The results of the field generated by the wireless communication system operating at the frequency f = 5 GHz are presented. The numerical finite difference time domain (FDTD) method was used. The influence of the values of electric permittivity and conductivity of concrete on the field intensity values was discussed in detail.

PL

Celem publikacji jest analiza wpływu zmienności wartości parametrów elektrycznych nieidealnego i absorbującego dielektryka (beton zwykły) na wartości natężenia pola elektrycznego. Również dokonano szczegółowej analizy wpływu średnicy zbrojenia, liczby rzędów oraz rozstawu pomiędzy prętami na wartości natężenia pola elektrycznego. Przedmiotem badań był model zawierający ścianę nośną wykonaną z betonu (absorbujący dielektryk) wraz ze zbrojeniem w postaci stalowych prętów (przewodnik). Analizowano cztery, powszechnie stosowane w budownictwie układy zbrojenia. Dodatkowo dyskusji poddano wpływ parametrów elektrycznych (przenikalność elektryczna, konduktywność) na wartości natężenia pola obliczone dla niejednorodnych, złożonych struktur materiałowych. Zaprezentowane zostały wyniki pola generowanego przez system komunikacji bezprzewodowej pracujący przy częstotliwości f=5 GHz. Zastosowano numeryczną metodę różnic skończonych w dziedzinie czasu (FDTD). Szczegółowo omówiono wpływ stosowanych w literaturze wartości przenikalności elektrycznych oraz konduktywności betonu na wartości natężenia pola.

11

Studies on the behaviour of steel fibre-reinforced concrete under monotonic and repeated cyclic stress in compression

Jayanth K., Shesha Prakash M. N., Suresh G. S., Naveen B. O.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e50, 2022

EN

Steel fibre-reinforced concrete (SFRC) has shown better performance behaviour with respect to the post-crack strength and in restricting the crack width and its propagation. Studies on behaviour of SFRC under repeated loading are a significant work. Behaviour of reinforced concrete structures during ground excitations in the form of earthquake forces could be significantly improved by addition of steel fibres in suitable dosage. Fibre type, aspect ratio, and dosage of fibres significantly influence the behaviour of steel fibre-reinforced concrete. Here, the work carried by various researchers with respect to the studies on the behaviour of SFRC under monotonic and cyclic stress in compression is presented. An experimental investigation on stress–strain characteristics of SFRC under monotonic loading in compression was carried, comprising M20 grade concrete, hooked-end steel fibres (l = 50 mm, diameter = 1 mm), and varying fibre dosages of 1.0, 1.25, 1.5, and 1.75% by volume of concrete. The stress–strain characteristics arrived based on the above experimental studies were compared with theoretical stress–strain characteristics, based on the equations proposed in literature. This served in understanding the behaviour of SFRC with respect to their stress–strain characteristics using experimental studies and by theoretical models, and analyse the extent of agreement and acceptance.

12

Badanie właściwości mechanicznych betonu ze zbrojeniem rozproszonym z włókien syntetycznych

Blazy Julia, Drobiec Łukasz

Izolacje

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2021

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R. 26, nr 4

74--78

PL

Fibrobeton, czyli beton zbrojony włóknami, otrzymywany jest przez dodanie do mieszanki betonowej włókien metalicznych lub niemetalicznych. Przeprowadzone badania miały na celu sprawdzenie, czy norma PN-EN 14651, przeznaczona do trzypunktowego testu zginania betonowych próbek zbrojonych włóknami metalicznymi, może być również zastosowana do badań betonu z włóknami syntetycznymi. Zbadano ponadto urabialność i wytrzymałość na ściskanie betonu z włóknami i bez nich. Sprawdzono również, czy dana objętość i rodzaj zastosowanej fibry mógłby zastąpić tradycyjne zbrojenie prętami stalowymi, a więc czy badany kompozyt może pełnić funkcję konstrukcyjną. W ramach badań została przygotowana betonowa mieszanka bez włókien oraz mieszanka z dodatkiem 0,22% (2 kg/m3) włókien syntetycznych. Dla obu mieszanek ilość cementu, kruszywa, wody i superplastifikatora była identyczna. W artykule omówiono podstawy prowadzenia badań, zastosowane materiały, sposób przygotowania próbek oraz technikę badań i wyniki badań wytrzymałości na ściskanie.

EN

Fiber-reinforced concrete is obtained by adding metallic or nonmetallic fibers to the concrete mixture. The tests were carried out to check whether the PN-EN 14651 standard, intended for three-point bending test the concrete samples reinforced with metallic fibers, can also be used for testing the concrete samples reinforced with synthetic fibers. In addition, the workability and compressive strength of concrete with and without fibers were tested. It was also checked whether used volume and type of fiber could replace traditional reinforcement with steel bars, and thus whether the tested composite can function as a structure. As part of the research, concrete mixture without fibers and with the addition of 0,22% (2 kg/m3) of synthetic fibers were prepared. For both mixtures, the amount of cement, aggregate, water and superplasticizer was identical. The article presents the basics of testing, materials used, method of sample preparation as well as the test technique, and the results of the compressive strength tests.

13

Wpływ włókien polimerowych na wytrzymałość na ściskanie i rozciąganie betonu w świetle norm PN-EN 206 i PN-EN 14651

Blazy Julia, Drobiec Łukasz

Inżynieria i Budownictwo

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2021

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R. 77, nr 8

391--396

PL

Przedstawiono możliwość zastosowania normy PN-EN 14651, przeznaczonej do badania betonów z fibrą stalową, do określenia wytrzymałości na rozciąganie przy zginaniu betonów z dodatkiem 2,0 i 3,0 kg/m3 włókien polimerowych o różnej geometrii i formie. Pozostały skład mieszanki betonowej był niezmienny w przypadku każdej serii. Opisano również użyte materiały, metodykę badań oraz wyniki badań konsystencji i wytrzymałości na ściskanie betonów z fibrą i bez fibry. Przeprowadzono analizę uzyskanych wyników i podsumowano wpływ włókien niemetalicznych na właściwości betonu.

EN

In the article, the possibility of use the PN-EN 14651 standard, intended for testing concretes with steel fibers, to determine the flexural strength of concrete with the addition of 2.0 and 3.0 kg/m3 of polypropylene fibers of different geometry and form was presented The remaining composition of the concrete mix was the same for each series. Additionally, the used materials, the methodology of tests, results of consistency tests and the evaluation of the compressive strength of concrete with and without fibers were discussed. Finally, the obtained results were analyzed and the influence of non - metallic fibers on the properties of concrete was summarized.

14

O reakcji stali z matrycą cementową w betonie zbrojonym

Kurdowski Wiesław

Inżynieria i Budownictwo

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2021

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R. 77, nr 7

320--323

PL

Badania strefy przejściowej stal pręta zbrojeniowego - matryca cementowa wykazały, że jony żelaza dyfundują do matrycy cementowej i reagują z jonami wapniowymi, z utworzeniem uwodnionego żelazianu wapnia. Po trzech miesiącach zaznacza się również reakcja jonów żelaza z głównym składnikiem zaczynu, jakim jest faza C-S-H. Początkowo jony żelaza wnikają pomiędzy warstwy tej fazy, a następnie powodują jej stopniową przemianę w uwodniony żelazian wapnia. Powstaje warstewka uwodnionego żelazianu wapnia na matrycy cementowej. Natomiast dyfuzja jonów wapnia do warstewki pasywacyjnej na stali jest znacznie mniej zaawansowana, niż jonów żelaza do matrycy cementowej. Wykonane mikroanalizy pokazują, że dyfuzja jonów żelaza przeważa, a jony wapnia mają bardzo mały wpływ na skład warstewki pasywacyjnej na stali. Nie są one „ruchliwe”, mimo że występują w dużym stężeniu w roztworze w fazie ciekłej matrycy cementowej. Główną rolę w tych procesach odgrywają jony żelaza, dyfundujące z pręta zbrojeniowego do matrycy cementowej.

EN

The study of transition zone - steel of the reinforcing rod cement matrix was shown that the iron ions are diffusing to the cement matrix and are reacting with the calcium ions, with the formation of hydrated calcium ferric. Already after 3 months the reaction of iron ions with the main component of the cement paste i.e. C-S-H phase is evident. Initially the iron ions are penetrating between the layers of this phase and next they are causing its gradual transformation in hydrated calcium ferric. Thus the layer of hydrated calcium ferric on the cement matrix is formed. However, the diffusion of calcium ions to the passivation film on steel is significantly less advanced than the ferric ions to the cement matrix. The microanalysis are showing the the iron ions diffusion is prevailing and the calcium ions have the low influence on the composition of passivation film on steel. They are not “movable”, despite that they have high concentration in the liquid phase in cement matrix. The main role in these processes the ferric ions are playing, which are diffusing from reinforcing bar to the cement matrix.

15

Effect of Modified Carbon Nanotubes Epoxy on the Mechanical Properties of Concrete Reinforced with FRP Sheets

Kazemi Hamid, Heydari Mostafa, Bamoharam Fateme Farash

Civil and Environmental Engineering Reports

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2021

|

Vol. 31, no. 3

177--196

EN

Today, using Fiber Reinforced Polymer (FRP) sheets is one of the conventional methods in retrofitting concrete structures. Some factors affecting FRP sheets proper performance include mechanical properties, surface specifications, connector’s material and connecting approach in concrete elements. Previous studies showed that FRP epoxy resin and its basic surface have a significant impact on the ultimate bearing capacity. In line with the development of nanotechnology in recent years, this paper presents an experimental study to show the effects of adding the best percentage of nano-carbons to adhesive resin and evaluate the ultimate axial, shear and bending strengths in concrete samples. The results show that using FRP with carbon nanotube reinforced resins will significantly increase stiffness and ductility by 100%; moreover, it shows an effective increase of almost 13% in axial and flexural strengths of specimens.

16

Flexural cracking behavior and calculation approach of reinforced highly ductile fiber-reinforced concrete beams

Zhang Min, Deng Mingke, Wu Zhiyan, Pan Jiaojiao

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

320--333

EN

Highly ductile fiber-reinforced concrete (HDC) is a class of cementitious composites reinforced with polyvinyl alcohol (PVA) fibers and exhibits strain-hardening behavior and multiple fine cracks under tension. This study aims to evaluate the cracking behavior and propose a simple calculation approach of the crack width and crack spacing of reinforced HDC (RHDC) flexural members. The four-point bending tests were conducted for RHDC beams with a different ultimate tensile strain of HDC and tensile reinforcement ratio. The flexural cracking performance of beams was mainly analyzed. The results showed that the width, spacing, height of flexural cracks of RHDC beams was significantly smaller compared with those of reinforced concrete (RC) beams. An increase in the ultimate tensile strain of HDC decreases the crack width and crack height while has little influence on the average crack spacing of RHDC beams. The effect of the tensile reinforcement ratio on the crack width is notable for RHDC beams with a higher ultimate tensile strain of HDC. The increasing of the tensile reinforcement ratio decreases the average crack spacing and crack height of RHDC beams. Furthermore, theoretical formulas for the average crack spacing, average crack width, and maximum crack width of RHDC beams were proposed based on the bond interaction between rebars and HDC and the fiber bridging stress. The predicted values have good agreement with the experimental values, indicating that the proposed method is reliable to evaluate the crack behavior of RHDC flexural members. Based on an accurate validation, the effect of cover thickness, HDC strength, and rebar diameter on the crack behavior of RHDC beams was conducted and found consistent with the law of RC beams.

17

The impact of the agressive acid environment on RC constructions

Blikharskyy Yaroslav, Khmil Roman, Blikharskyy Zinoviy, Shnal Taras

System Safety : Human - Technical Facility - Environment

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2020

|

Vol. 2, nr 1

223--229

EN

The main issue of the article is the corrosion of the reinforced concrete elements by the co-influence of the aggressive and power factors. The problem of corrosion is extremely actual one. Therefore the tests were carried out upon the specimens considering the corrosion in the acid environment, namely 10 % H2SO4. The acid environment H2SO4 was taken as a model of the aggressive environment. Conclusions concerning the corrosion model of the cross section and investigation of stress-strain state have been made. That material concerns the problem of the reinforced concrete corrosion as a whole construction. Reinforced concrete beams were tested with and without the co-action of the aggressive environment and power factor.

18

Simulation of the stress-strain state of eccentrically compressed and tensioned reinforced concrete beams

Karpiuk Vasyl, Somina Yuliia, Maistrenko Oksana, Karpiuk Fedir

System Safety : Human - Technical Facility - Environment

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2020

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Vol. 2, nr 1

207--214

EN

The paper deals with the working peculiarities of the support zones of reinforced concrete elements subject to bending with due account of the eccentric compression and tension. The authors performed simulation of the stress-strain behaviour of the indicated structures with the aid of “Lira” software which results are shown in the graphical and tabulated form. The performed simulation allowed of tracing the work of the studied sample beams till collapse. Such approach made it possible to single out and generalize the main collapse patterns of the inclined cross-sections of the reinforced concrete elements subject to bending on which basis the authors developed the improved method to calculate their strength (Karpiuk et al., 2019).

19

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

|

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.

20

Inżynier Kajetan Mościcki (1855-1933) i jego działalność na rzecz budowy ulic i mostów Warszawy

Mistewicz Marek

Kwartalnik Historii Nauki i Techniki

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2020

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T. 65, nr 1

9--36

EN

The article presents the problems of building and maintaining urban transport infrastructure in Warsaw at the turn of the 20th century. The text concerns Kajetan Mościcki (1855-1933), engineer, who was appointed by the acting Mayor of Warsaw, General Sokrates Starynkiewicz, to the position of senior city engineer and head of the municipal construction department, where he worked from 1889 to 1909. During this period, he paved the streets which were worn or damaged by sewerage works with wooden blocks and covered the sidewalks with concrete slabs. He designed the first slip road in the Kingdom of Poland in the form of a spiral, and he also participated in the construction of the oldest road engineering structures made of reinforced concrete, located in Ujazdowski Park and on Karowa street in Warsaw, the first Warsaw power plant and the second city bridge across the Vistula. In addition to his professional activity, Kajetan Mościcki was an inventor in the fields of mechanics and electrical engineering. At the end of his life, he founded an award that the Polish Academy of Arts and Sciences was to grant to Polish scientists for outstanding achievements.