scholarly journals DUCTILITY RESPONSE OF HYBRID FIBRE REINFORCED CONCRETE BEAMS

Author(s):  
Eswari Natarajan

Abstract: The effect of fibre content on the Strength and ductility behaviour of hybrid fibre reinforced concrete (HFRC) beams having different fibre volume fractions was investigated. The parameters of this investigation included service load, ultimate load, service load deflection, ultimate load deflection, crack width, deflection ductility and energy ductility. The fibre volume fraction (Vf) ranged from 0.0 to 2.0 percent. Steel and polyolefin fibres were combined in different proportions and their impact on the above parameters was studied. The ductile response of hybrid fibre reinforced concrete beams was compared with that of control beam. The test results show that addition of 2.0 percent by volume of hybrid fibres improve the strength and ductility appreciably. Empirical expressions for predicting the strength and ductility of hybrid fibre reinforced concrete (HFRC) are proposed based on regression analysis. A close agreement has been obtained between the predicted and experimental results.

2018 ◽  
Vol 7 (4.20) ◽  
pp. 502 ◽  
Author(s):  
Amer Mohamed Ibrahim ◽  
Ahmed Abdullah Mansor ◽  
Wissam D. Salman ◽  
Mohammed Jaafar Hamood

This paper presents an experimental investigation on the strength of bubbled wide reinforced concrete beams with different types of shear steel plates. Eight specimens with dimensions of 215x560x1800mm were investigated. The studied variables deal with replacement of 10mm stirrups diameter stirrups spaced at 125mm by shear steel plates having equivalent cross-sectional area for stirrups at mid legs height with circular opening of different thicknesses (3, 4 and 5mm). Four specimens were without any bubbles and the others with bubbles. This study showed that the shear steel plates is a good alternative for replacing the stirrups and gives increasing in yield, ultimate load and deflection (at service load) with 5% , 15% and 9% on the average when using the bubbles. Without using bubbles, the aspect ratio of shear steel plates bounded between the boundaries 4.5 to 8 gave increased the ductility by 36%. Using the bubbles in specimens was decreased 4.7% from the total weight of specimens. ACI 318-14(1) and EC 2(2) codes give a predicted deflection more than that obtained from experimental results by 16% on the average and by 24% when using bubbles.    


2019 ◽  
Vol 3 (2) ◽  
pp. 135
Author(s):  
Novita Ike Triyuliani ◽  
Sri Murni Dewi ◽  
Lilya Susanti

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%.


2020 ◽  
Vol 8 (6) ◽  
pp. 4856-4860

This paper presents the effects of adding basalt fibres on reinforced concrete beams. The fibre volume fraction Vf ranges from 0.0 to 2.0 %. First crack load, service load, yield & ultimate load and their corresponding deflections were noted. The ductility response of BFRC beams were evaluated. The results show that 1.5% by volume of basalt fibre improves the overall performances. The maximum increase in deflection and energy ductility was found to be 34 % and 39% respectively when compared to that of reference beam. The increasing application of basalt is noticed as an insulating material in the construction and automotive industry and less hazardous than asbestos fiber. Basalt fabrics are produce d for the structural, electro-technical purposes. Structural applications include electromagnetic shielding structures, various components of automobiles, aircraft, ships and household appliances.


Most commonly the reinforced concrete structures fail by exhibiting the flexural and shear pattern of cracks. So in order to avoid this type of failure and to increase the life span of the structure, the strengthening of the structural members has to be studied. The concept of using fibres in the concrete has more advantage in increasing the concrete strength. However, in this investigation two different types of fibre which has higher (Steel hooked end fibre) and lesser moduli (Polypropelene fibre) which increases the modulus of elasticity of concrete. This Hybrid combination of fibres will reduce the chances of brittleness and small crack formation in the concrete. The use of computer software to model these elements is much faster, and extremely cost-effective. Hence, the Non-linear Finite Element Analysis (FEA) of a Hybrid fibre reinforced concrete beams has been modelled and analysed using the ANSYS software package. The flexure and shear pattern of arrangements in control beam and three Hybrid fibre Reinforced concrete beams of different proportions (1%, 1.5% and 2%) were modeled and analyzed for the results of ultimate load, deflection and stiffness ratio of the beams.


In this paper, the flexural behavior of hybrid fibre reinforced concrete beams was investigated. Two types of hybrid fibres were used. used in this study, one is having high young’s modulus steel fibre (Hooked end) and another one is having low young’s modulus Polypropylene fibre with different proportions. Nine types of reinforced concrete beams were made by using M50 grade high strength concrete mix a volume factors of hybrid fibres as 1.5%. this beams includes conventional concrete, LC3 concrete and he beam with the following combinations of hybrid fibres such as OPC 100%, LC3 100%, SF100%, SF25% -PF75%, SF40%-PF60%, SF50%-PF50%, SF60%-PF40%, SF75%-PF25 %, PF100%, the working results shows that percentage proportion of combined SF-PF at 75%-25% had the best implementation on its flexural strength. Experimental results also shows that beam with SF75%-PF25% had their structural stiffness, ductility index and energy absorption capacity have been improved the most as compared with the conventional concrete and other fibre combinations of beams.


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