Wyniki wyszukiwania - BazTech

1

Research on the design method of flexural capacity of RC beams strengthen by ultra-high performance concrete

Wang Jiawei, Ying Feifei

Archives of Civil Engineering

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2024

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Vol. 70, nr 1

487--507

EN

Due to the increase in traffic volume, load level, and service life of existing bridges, the bending bearing capacity of reinforced concrete beams (hereinafter referred to as RC beams) has decreased, leading to safety issues. In order to solve the problem of insufficient flexural bearing capacity of RC beams, this article adopts the method of ultra-high performance concrete (UHPC) flexural strengthening RC beams, establishes a finite element model of UHPC-RC reinforcement system, and conducts stress analysis with reinforcement thickness, reinforcement range, reinforcement form, and reinforcement height as parameters to determine the optimal scheme of the reinforcement system. Based on the calculation results, a theoretical formula for the maximum principal stress and maximum deflection of the reinforcement system is proposed. To verify the feasibility of the plan, a reinforcement design was carried out on an existing beam, and it was found that the bending bearing capacity of the RC beam increased by 21%; the high tensile strength of UHPC and the addition of steel fibers have a good limiting effect on cracks; The steel plate of the reinforcement system can be used as a template, reducing construction costs and having good economy.

2

Management of the Special Processes – An Experimental Study of Bent Reinforced Concrete Beams

Michałowska-Maziejuk Dorota, Klimecka-Tatar Dorota, Ingaldi Manuela, Kaczmarska Bożena, Czajkowska Agnieszka

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 2

248--265

EN

The article presents an analysis of the results obtained from the testing of simply supported reinforced concrete beams subjected to four-point bending. The beams, with two levels of steel reinforcement (ρs1=1.26%, ρs2=0.71%), and dimensions of 0.12x0.30x3.30m, were subjected to loading involving a sudden increase in force with multiple unloading cycles to zero. The study included comparative analysis of deflection results obtained from experimental tests (calculated based on the curvature of the element and readings from measurement devices) with deflection values obtained through calculations based on two selected standards. Real values of ultimate bending moments were also compared with theoretical values. Additionally, compressive strength tests were conducted on eight cubic concrete specimens with a side length of b=150mm, obtained for each concrete batch. They constitute accompanying studies. Using standard procedures, strength and statistical parameters were estimated and evaluated, taking into account the assessment of the quality of the concrete production used to make the reinforced concrete beams. Ensuring compliance with the process of producing full-sized reinforced concrete beams with existing standard procedures, as well as attention to the quality of concrete production, contributed to achieving satisfactory results in the experimental tests. Knowledge about the impact of loading on mechanical properties enables effective management of factors shaping quality to obtain a construction material with optimal parameters.

3

Wpływ otworów technologicznych na nośność belek żelbetowych

Pozorski Zbigniew, Lisowski Tomasz

Nowoczesne Hale

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2023

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Nr 2

42--50

PL

Zastosowanie otworów technologicznych w belkach pozwala na bardziej ekonomiczne wykorzystanie dostępnej przestrzeni budynku. Otwór w elemencie konstrukcyjnym, nawet jeśli jest mały, powoduje istotne zaburzenie w rozkładzie naprężeń i odkształceń. Z tego powodu w miejscach występowania małych otworów należy zapewnić dodatkowe zbrojenie przenoszące siłę tnącą. W artykule przedstawiono dwie metody wyznaczania niezbędnego zbrojenia wokół otworu: metodę standardową oraz metodę kratownicową.

EN

The use of technological openings in beams allows for more economical use of the available building space. An opening in a structural element, even if it is small, causes a significant disturbance in the distribution of stresses and deformations. For this reason, in places with small openings, additional reinforcement should be provided to transfer cutting force. The article presents two methods of determining the necessary reinforcement around the opening: the standard method and the truss method.

4

The influence of a polyurea coating on bent reinforced concrete beams with various reinforcement ratios

Szafran Jacek, Matusiak Artur, Rzeszut Katarzyna, Jankowiak Iwona

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 1

art. no. e144579

EN

“Polyurea coatings as a possible structural reinforcement system” is a research project aimed at exploring possible applications of polyurea coatings for improving structural performance (including steel, concrete, wooden and other structures used in the construction industry). As part of the project, this paper focuses on evaluating the performance of bent reinforced concrete (RC) beams covered with a polyurea coating system. Easy polyurea application and its numerous advantages can prove very useful when existing RC structural elements are repaired or retrofitted. Laboratory tests of three types of RC beams with three different longitudinal reinforcement ratios were performed for the purposes of this paper. The tests were designed to determine the bending strength, performance and cracking patterns of the coated RC beams. In addition, a theoretical model was developed to predict the impact of the polyurea coating on the bending strength of the RC beams. On this basis, the effect of the coating on the bending strength and the performance of the coated beams at the ultimate limit state (ULS) was examined and analyzed. The results showed that the use of the polyurea coating has a positive impact on the cracking state of the RC beams subject to bending and little effect on their bending strength.

5

The impact of a polyurea layer on cracking and performance of reinforced concrete beams under breaking load

Szafran Jacek, Matusiak Artur, Rzeszut Katarzyna, Jankowiak Iwona

Structure and Environment

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2022

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Vol. 14, no. 3

76--82

EN

The paper discusses the results of laboratory experimental studies on reinforced concrete components (beams) with an outer polyurea layer. The important part of the study is the comparison of the results concerning the load-displacement relation for the reference beams (without the polyurea layer on their external surfaces) and those with the polyurea layer. The main conclusion from this part of the research is that the beam elements covered with a polyurea layer are protected against corrosion processes even in an emergency state. The occurrence of scratches, even of large size, is neutralized by the coating that effectively bridges them.

PL

W artykule zaprezentowano wyniki laboratoryjnych badań eksperymentalnych dotyczących elementów żelbetowych (belek) wraz z zewnętrzną warstwą polimocznika. Istotną częścią pracy jest porównanie wyników zależności obciążenie - przemieszczenie dla belek referencyjnych (bez warstwy polimocznika na powierzchniach zewnętrznych) oraz tych taką warstwę posiadającą. Kluczowym wnioskiem płynącym z tej części badań jest ten mówiący o tym, że elementy belkowe pokryte warstwą polimocznika zabezpieczone są przed korozją nawet w stanie awaryjnym. Występowanie rys nawet znacznych rozmiarów jest zneutralizowane poprzez skuteczne ich mostkowanie powłoką.

6

Investigation of defective reinforced concrete beams with obtained damage of compressed area of concrete

Blikharskyy Zinoviy, Lobodanov Мaksym, Vegera Pavlo

Production Engineering Archives

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2022

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Vol. 28, Iss. 3

225--232

EN

In the building industry, it is a frequent cause of damage to elements at different stages: during transportation, operation, installation, etc. Since replacing an element is not always possible due to various circumstances, it entails significant financial losses, logistics, and others. For this reason, the expediency of studying the effect of damage on the bearing capacity of reinforced concrete elements is growing. This effect is dependent on its type and has significant variability. In the case of the combination of the defect and damage in reinforced concrete elements, the complexity of the research of this element increases significantly. In this article is discussed: a review of damaged reinforced concrete elements; researching the influence of the damage and additional factors on the element; developed testing methodology for bending reinforced concrete elements with damage to concrete in a compressed zone with insufficient reinforcement, when performing damage to the action of the load and during the action of the load, is presented; the influence on the deformability and bearing capacity of the variability of damage on the sample with insufficient reinforcement is reflected, taking into account the factor of change in the load at which the damage is performed; a comparison is made of the dependence of the change in the actual height of the compressed zone on the change in the load on the elements; implementation of conclusions on the result of the study.