scholarly journals Pilot Studies of Concrete Beams Deformability Reinforced with Composite Reinforcement

2020 ◽  
Vol 24 (1) ◽  
pp. 103-114
Author(s):  
O. A. Vetrova
Keyword(s):  
Experimental Data ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Pilot Studies ◽  
Loading Level ◽  
Design Load ◽  
Composite Reinforcement

Purpose of research. Analysis is done on the basis of experimental data of loading level impact on deformability of beams with steel and composite fiberglass reinforcement at prolonged loads.Methods. Experimental studies of concrete bending elements of two series were carried out: the first is reinforced with composite fiberglass reinforcement of ASK class, the second is reinforced with steel reinforcement of А400 class. Studies of experimental samples were carried out under long-term loads. The structures were under different loads during the experiment: at design load, at 1.2 level from design load and at 1.5 from the design load. Concrete deformations and deflections of experimental beams of two series were fixed.Results. Dependence on time of concrete deformations of experimental samples of two series at different loading levels, dependence of deflection growth on load application level, influence dependence of loading level of elements on speed and intensity of creep deformation growth of beams with fiberglass and steel reinforcement are stated on the basis of experimental data. In particular, the bends of all samples with fiberglass reinforcement exceeded the maximum permissible value, while the maximum deflection of reinforced concrete beams in the middle of the section did not exceed maximum permissible value.Conclusion. On the basis of the obtained data, conclusions are drawn on the nature and magnitude of long-term deformations of beams with fiberglass and steel reinforcement at different levels of long-term loads. This conclusion is significant in practical sense when using concrete structures with composite reinforcement taking into account a small number of research data.

scholarly journals Limiting Reinforcement Ratios for Hybrid GFRP/Steel Reinforced Concrete Beams

2021 ◽  
Vol 11 (1) ◽  
pp. 01-11
Author(s):  
Duy Phan Nguyen ◽  
Viet Quoc Dang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Equilibrium Equations ◽  
Steel Reinforced Concrete ◽  
Glass Fiber Reinforced ◽  
Load Carrying

In this work, a theoretical approach is proposed for estimating the minimum and maximum reinforcement ratios for hybrid glass fiber reinforced polymer (GFRP)/steel-reinforced concrete beams to prevent sudden and brittle failure as well as the compression failure of concrete before the tension failure of reinforcements. Equilibrium equations were used to develop a method for determining the minimum hybrid GFRP/steel reinforcement ratio. A method for determining the maximum hybrid GFRP/steel reinforcement ratio was also developed based on the equilibrium of forces of the balanced failure mode. For estimating the load-carrying capacity of concrete beams reinforced with hybrid GFRP/steel, less than the minimum and more than the maximum reinforcement ratio is recommended. Comparisons between the proposed expressions, experimental data, and available test results in the literature shows good agreement between the theoretical and experimental data, with a maximum discrepancy of 7%.

scholarly journals EXPERIMENTAL INVESTIGATIONS OF THE LOSSES OF PRESTRESSING IN FINE REINFORCED CONCRETE ELEMENTS

2018 ◽  
Vol 22 (1) ◽  
pp. 112-117 ◽  
Author(s):  
S. G. Parfenov ◽  
M. V. Morgunov
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Experimental Investigations ◽  
Fine Grained ◽  
Concrete Shrinkage ◽  
Prestressing Force ◽  
Shrinkage And Creep

The article deals with late losses of prestressing of reinforcement due to shrinkage and creep in fine reinforced concrete structures. Creep deformations can several times exceed the elastic straincaused by load. The most common in practice caseof the development of concrete creep is slowly decreased creeping with timewith a rather high initial rate of the development in the first hours after loading. It is typical for stresses that do not exceed the long-term resistance of concrete. Experimental study of deformation of shrinkage and creep of fine-grained concrete allows us to compare the loss of prestressing due to concrete shrinkage and creep. Usually there is an aggregate effect of these factors, which significantly complicates the study of the processes occurring in concrete during long-term exposures. Basically, the results obtained during testing of concrete prisms are used to compare stress-related properties of concrete, but this is not enough to study the loss of prestressing due to concrete shrinkage and creep and testing should be carried out on elements reinforced with prestressed reinforcement to take into account changes in prestresses and redistribution of stresses on the height of the cross section (depth) of the element with a prolonged action of the prestressing force. The results of experimental studies of rectangular reinforced concrete beams at loadcase of different ages of t = 14, 28, 280 and 320 days are analyzed. The losses from rapid creep, shrinkage losses, total losses from shrinkage and creep are considered. The experimental data are presented in the form of graphs and tables. There was performed comparison of the experimental data with the calculated ones determined according to the current standards, and for shrinkage according to the method proposed by I.I. Ulitsky as well.

scholarly journals Stress-deformed state of proof areas of reinforced concrete beams

2021 ◽  
Vol 2 (92) ◽  
pp. 32
Author(s):  
Stepan Neutov ◽  
Zlata Holovata ◽  
Daria Kirichenko
Keyword(s):  
Concrete Beams ◽  
Experimental Studies ◽  
Breaking Load ◽  
Load Level ◽  
Reinforced Concrete Beams ◽  
Longitudinal Reinforcement ◽  
Shear Span ◽  
Long Acting ◽  
Inclined Cracks

Abstract. The results of experimental studies of the stress-strain state of the support sections of rein-forced concrete beams from some of the most signifi-cant factors are presented. It was found that during long-term loading such factors are the level of the initial loading; concrete class; the percentage of transverse reinforcement in the shear span; the per-centage of longitudinal reinforcement in the com-pressed zone; the percentage of longitudinal working reinforcement in the extended zone. With an increase in the class of concrete, the moment corresponding to the appearance of normal cracks and the shear force corresponding to the appearance of inclined cracks slightly increase, although they lag behind the growth of the class of concrete. The process of crack-ing in the investigated beams begins, as a rule, with the appearance of normal cracks in the zone of pure bending at a load level (0.15... 0.33) from breaking. Inclined cracks appeared somewhat later, at load levels close to 0.5 of breaking. With a relatively high percentage of longitudinal reinforcement, the first oblique cracks appeared in the middle of the beam height in the shear span. At load levels close to 0.7, the process of formation of new cracks practically stops, and already existing cracks open more inten-sively. During the period of exposure to a constant long-term load, the width of the opening of normal cracks increased on average by 1.2–1.5 times, and the width of the opening of inclined cracks increased by 2.5–3 times. In the process of loading before the destruction of previously long-loaded beams, the width of the opening of normal cracks remained practically unchanged, and the width of the opening of inclined cracks increased by 1.2–1.7 times, and the breaking load for beams loaded with a preliminary long-acting load of 0.85 from the breaking load in-creased by 13–15 % compared to short-term loading. The opening width of inclined cracks along the length was different, its maximum value was ob-served in the middle of the height of the section of the support sections of the beams.

scholarly journals Finite element analysis of reinforced concrete deep beam with large opening

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Elsayed Ismail ◽  
Mohamed S. Issa ◽  
Khaled Elbadry
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
The Other ◽  
Deep Beam ◽  
Web Openings ◽  
Design Load ◽  
Large Opening

Abstract Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.

scholarly journals RETROFITTING AND DACTILITY OF REINFORCED CONCRETE BEAMS USING AN EXTERNAL REINFORCEMENT METHOD

2019 ◽  
Vol 3 (2) ◽  
pp. 135
Author(s):  
Novita Ike Triyuliani ◽  
Sri Murni Dewi ◽  
Lilya Susanti
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Concrete Beams ◽  
Concrete Block ◽  
Steel Reinforcement ◽  
Reinforced Concrete Beams ◽  
Building Structures ◽  
Average Increase ◽  
External Reinforcement ◽  
Strength And Ductility

The innovations strengthening building structures are important topics. Failure in structures such as beams and columns due to time, re-functions of a building, even initial design errors that are weak or lack the safety factor of a building structure. External reinforced concrete beams are one of the beams currently being developed. It is a concrete block with reinforcement of steel reinforcement on the outer (external) of the beam. This study aims to determine the index of increasing beam strength and ductility after retrofitting external steel reinforcement, which has the dimension of beams 15 x 15 x 100 cm, repeating 12 pcs, with external reinforcement each 6 pcs 2Ø6 and 3Ø6. The results from this study are an increasing the index of beam flexural strength after retrofit with external steel reinforcement. Meanwhile, beams after retrofit with 2Ø6 external steel have an average increase index of 1.25 and 1.21 while for external steel 3Ø6 are 1.29 and 1.60 respectively. The ductility depends on the value of ultimate load and maximum deflection that occurs, where the ductility value for the comparison of each specimen experiences a reduction in the average ductility value with 2Ø6 external steel which is 37.74% and 70.95% while with 3Ø6 external steel is 61,65% and 60.62%. Berbagai inovasi upaya peningkatan kekuatan struktur bangunan telah menjadi bahasan yang penting. Kegagalan pada struktur seperti balok dan kolom karena umur, alih fungsi suatu bangunan, bahkan kesalahan desain awal yang lemah atau kurang memenuhi faktor keamanan suatu struktur bangunan. Balok beton bertulangan eksternal adalah salah satu balok yang sedang dikembangkan pada saat ini, yaitu balok beton dengan perkuatan tulangan baja di sisi terluar (eksternal). Penelitian ini bertujuan untuk mengetahui indeks peningkatan kekuatan balok dan daktilitas setelah dilakukan perbaikan menggunakan tulangan baja eksternal, dengan dimensi balok 15 × 15 × 100 cm berulang 12 buah, penambahan tulangan baja eksternal masingmasing 6 buah 2Ø6 dan 3Ø6. Hasil yang didapat dari penelitian ini adalah indeks peningkatan kekuatan lentur balok setelah dilakukan perbaikan menggunakan tulangan baja eksternal. Dimana balok setelah dilakukan perbaikan dengan baja eksternal 2Ø6 memiliki indeks peningkatan rata-rata 1,25 dan 1,21 sedangkan untuk baja eksternal 3Ø6 masing-masing 1,29 dan 1,60. Daktilitas tergantung dari nilai beban ultimit dan lendutan maksimum yang terjadi, dimana nilai daktilitas untuk perbandingan tiap benda uji mengalami reduksi nilai daktilitas rata-rata dengan baja eksternal 2Ø6 yaitu sebesar 37,74% dan 70,95% sedangkan dengan baja eksternal 3Ø6 sebesar 61,65% dan 60,62%.

scholarly journals EXPERIMENTAL STUDIES OF REINFORCED CONCRETE BEAMS STRENGTHENED WITH STEEL FIBER JACKET

2020 ◽  
pp. 34-45
Author(s):  
O. Radaikin ◽  
L. Sharafutdinov
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Breaking Load ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Steel Fiber Reinforced Concrete ◽  
Joint Work ◽  
Loaded Crack

The purpose of the study is to experimentally study the joint work of steel fiber reinforced concrete (SFB) reinforcement jacket and reinforced concrete beams at all stages of loading to further develop a methodology for calculating this method of reinforcing bending elements. The main results of the study consist in assessing the strength, stiffness, fracture toughness, as well as the nature of fracture with a picture of the development of cracks for the examined 4 samples (two with a jacket of reinforcement, two - control - without reinforcement). It has been established that the use of SFB jacket with a thickness of 45 mm and with a fiber content percentage of 2,5% (at a flow rate of 196 kg/m3) increases the breaking load by 20 %, stiffness from 3,4 to 11 times as it is loaded, crack resistance 2,4-2,8 times. The results are compared with computer modeling in ANSYS PC: the discrepancy in the load of crack formation, fracture and deflection values for full-scale samples and a computer model are within 6,3 %, which indicates the reliability of the numerical results and the possibility of using the proposed computer models in further studies on topic of the article.

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