Flexural Behavior Of Steel Fiber Reinforced Prestressed Concrete Beams And Double Punch Test For Fiber Reinforced Concrete
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Flexural Behavior Of Steel Fiber Reinforced Prestressed Concrete Beams And Double Punch Test For Fiber Reinforced Concrete
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Author : Netra Bahadur Karki
language : en
Publisher:
Release Date : 2012
Flexural Behavior Of Steel Fiber Reinforced Prestressed Concrete Beams And Double Punch Test For Fiber Reinforced Concrete written by Netra Bahadur Karki and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Fiber-reinforced concrete categories.
Steel fibers have widely been used in the past to reinforce brittle materials in many nonstructural applications such as pavement, tunneling lining, etc. On the basis of numerous previous studies, ACI 318-11 [2011] has recently accepted steel fiber as a minimum shear reinforcement replacement with minimum 0.75% volume fraction for both reinforced concrete and prestressed concrete members. However, not much previous research has talked about the flexural behavior of fiber reinforced concrete (FRC). As per ACI 318-11 for tension-controlled sections, the net tensile strains in the outermost layer of steel, et, should be greater than or equal to 0.005 and for the moment redistribution in continuous beam the section should sufficiently ductile (et [greater or equal to] 0.0075). For this, the sections should have small longitudinal reinforcement ratio which ultimately leads to an inefficient beam section with a large cross-sectional area. In contrast, the use of smaller concrete cross sections can lead to a diminished ductile flexural behavior as well as premature shear failure. In this context, the use of steel fiber reinforced concrete could be a potential solution since fiber can increase both the concrete shear strength and it's usable compressive strains. However limited previous researches on the flexural behavior on SFRC beams are available and most of them are of small scales and concentrated only basically for shear behavior. To the best of our knowledge, the large-scale prestressed fiber reinforced concrete beam specimens have yet to be studied for flexure behavior. In this project, six large scale prestressed concrete beams with or without steel fiber along with some material test were tested. Our experimental investigations indicated that even with inclusion of small percentage volume of fraction of steel fiber (Vf =0.75%) could not only increase the ductility and shear strength of the SFRPC beam but also change the failure pattern by increasing usable strain in concrete and steel. A modification on the limit for c/dt ratio and [phi] factor for design of flexural member given in current ACI could be proposed which could imply the smaller sections with higher longitudinal reinforcement ratio and less shear reinforcement. could be used. Any standard material test results have to ensure that FRC has, at least, been batched properly and it can give indications of probable performance when used in structures. In the current material testing method suggested by ACI, the third point bending test (ASTM C1609) has an inherent problem in that the coefficients of variations for post cracking strength and residual strength are generally very high on the order of 20%. The direct tensile test can be a more appropriate material. However, it is currently not recommended as standard method in the U.S. Because of it's difficultly in gripping arrangement which will lead to cracking of the specimen at the grips. Both the test methods also require close loop servo controlled machine. The round panel test method (ASTM C1550) requires large size specimen and heavy steel supports prevents performing test in small laboratories. Split cylinder test (ASTM C496), do not necessarily reflect the true properties of the material as the specimen is forced to fail in the line of the application of the load and the test method is also not recommended by ACI for SFRC. In order to improve the material assessment procedure, the double Punch Test (DPT) introduced by Chen in 1970 [Chen, 1970] was extensively evaluated to develop a simple, quick and reliable testing method for SFRC. Various tests were carried out in order to evaluate peak and residual strength, stiffness, strain hardening and softening, toughness and other post crack properties. Our test results indicated that the DPT method could be immersed as reliable, easier and economical material test method. It could be used to distinguish the peak strength, residual strength, toughness stiffness and crack resistance, of different SFRC mixtures with less scatter results compared to other material test methods.
Shear Behavior Of Steel Fiber Reinforced Prestressed Concrete Beams Without Shear Reinforcement
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Author : Jae-Sung Cho
language : en
Publisher:
Release Date : 2011
Shear Behavior Of Steel Fiber Reinforced Prestressed Concrete Beams Without Shear Reinforcement written by Jae-Sung Cho and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Fiber-reinforced concrete categories.
The ACI 318-08 building code allows to use the steel fiber reinforcement as alternative shear reinforcement with satisfying certain criteria when a beam is required minimum shear reinforcement. However, this provision applies to a nonprestressed and prestressed concrete beam such that it could be conservative since the shear strength of prestressed concrete beam is generally enhanced due to the prestressing force. This is due partially to the fact that the provision has been accepted based on researches, mostly conducted in nonprestressed concrete beam. Most of experiments conducted for prestressed concrete beam in small scale tests, with a height of specimens were less than 10 in. A larger scale of experiment is required due to concerns of size effect. In addition, in order to evaluate the qualification of a Steel Fiber Reinforced Concrete (SFRC) mixture used for structural applications, such as increasing shear resistance, a material evaluation method is essential. Currently ASTM or ACI Committee 544 (Fiber-Reinforced Concrete) does not recommend any standardized test method for evaluating shear performance of a particular SFRC material. This study addresses the research gaps described above by testing large-scale Steel Fiber Reinforced Prestressed Concrete (SFRPC) beams as well as developing a simple laboratory test techniques. A total 13 simply-supported beams for large-scale test with a shear span to effective depth ratio of 3.0 and a height of 24 in. were subjected to monotonically-increased, concentrated load. The test parameters were mainly included compressive strength, volume fraction of steel fibers, compressive reinforcement ratio. The results of large-scale test showed that the use of hooked steel fibers in a volume fraction greater than or equal to 0.50% volume fraction of steel fibers (67 lb per cubic yard), which is less than requirement by ACI 318-08 (0.75%, 100 lb per cubic yard), led to substantial enhancement of shear behaviors including the first cracking, the ultimate, and ductility. High compressive strength of SFRC, greater than 9000 psi, which is higher than ACI 318-08 requirement (less than 6000 psi) could be used as well. However, there was no significant effect from compressive reinforcement ratio. A simply shear test method for SFRC was proposed in this study. The test apparatus is almost exactly the same as the conventional ASTM bending test with only minor modification, in addition, it could simulate a pure shear stress by adjusting loading and support positions. By introducing a proper reinforcement for bending stress, it was possible to evaluate shear performance of SFRC with clear and uncomplicated shear stress field in the critical section.
Double Punch Test For Evaluating The Performance Of Steel Fiber Reinforced Concrete
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Author : Aaron Paul Woods
language : en
Publisher:
Release Date : 2012
Double Punch Test For Evaluating The Performance Of Steel Fiber Reinforced Concrete written by Aaron Paul Woods and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
The objective of this study is to develop test protocols for comparing the effectiveness of fiber-reinforced concrete (FRC) mixtures with high-performance steel fibers. Steel fibers can be added to fresh concrete to increase the tensile strength, ductility, and durability of concrete structures. In order to quantify steel fiber-reinforced concrete (SFRC) mixtures for field applications, a material test capable of predicting the performance of SFRC for field loading conditions is required. However, current test methods used to evaluate the structural properties of FRC (such as residual strength and toughness) are widely regarded as inadequate; a simple, accurate, and consistent test method is needed. It was determined that the Double-Punch Test (DPT), originally introduced by Chen in 1970 for plain concrete, could be extended to fiber-reinforced concrete to satisfy this industry need. In the DPT, a concrete cylinder is placed vertically between the loading platens of the test machine and compressed by two steel punches located concentrically on the top and bottom surfaces of the cylinder. It is hypothesized that the Double-Punch Test is capable of comparing future fiber-reinforcement design options for use in structural applications, and is suitable for evaluating FRC in general. The DPT Research and Testing Program was administered to produce sufficient within-laboratory data to make conclusions and recommendations regarding the simplicity, reliability, and reproducibility of the DPT for evaluating the performance of SFRC. Several variables (including fiber manufacturer, fiber content, and testing equipment) were evaluated to verify the relevance of the DPT for FRC. In this thesis, the results of 120 Double-Punch Tests are summarized and protocols for its effective application to fiber-reinforced concrete are recommended. Also, fundamental data is provided that indicates the DPT could be standardized by national and international agencies, such as the American Society of Testing and Materials (ASTM), as a method to evaluate the mechanical behavior of FRC. This project is sponsored by the Texas Department of Transportation (TxDOT) through TxDOT Project 6348, "Controlling Cracking in Prestressed Concrete Panels and Optimizing Bridge Deck Reinforcing Steel," which is aimed at improving bridge deck construction through developments in design details, durability, and quality control procedures.
Aci Structural Journal
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Author :
language : en
Publisher:
Release Date : 1988
Aci Structural Journal written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with Concrete categories.
Flexural Behavior Of Steel Fiber Reinforced Rubberized Concrete
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Author : Zaid S. Hussein
language : en
Publisher:
Release Date : 2011
Flexural Behavior Of Steel Fiber Reinforced Rubberized Concrete written by Zaid S. Hussein and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Reinforced concrete categories.
This thesis focused on the study of flexural load-deflection behavior of Steel Fiber Reinforced Rubberized Concrete (SFRRC) up to first crack-load. Specifically, it involved an experimental method to examine simultaneous flexural load-deflection response measurements on normal Portland Cement Concrete, Rubberized Concrete, Steel Fiber Reinforced Concrete, and SFRRC, and other. Other basic tests were addressed to characterize fresh mix and constituent material properties. Regression models were developed to predict the following: (i) first-net deflection, (ii) net deflection at any applied load, and (iii) first-crack load at different mix combinations of crumb rubber and steel fiber. Results from this investigation showed that the incorporation of crumb rubber inherits the elastic property to concrete; however, the additional gain in elasticity from the increased strength due to the incorporation of steel fiber as a second constituent played a more dominant role in improving this property.
Experimental Study Of Flexural Behavior Of Preflex Sfrc Encased Steel Joist Composite Beams
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Author : Niraj Narendra Bora
language : en
Publisher:
Release Date : 2020
Experimental Study Of Flexural Behavior Of Preflex Sfrc Encased Steel Joist Composite Beams written by Niraj Narendra Bora and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
This study investigates the behavior of encased steel composite beams in straight and preflex beams, constructed and tested at Civil Engineering Laboratory Building (CELB). Upwards camber is provided in the steel sections in steel angles and HSS tube in the composite beam encased in Steel fibers reinforced concrete (SFRC). Experimental procedure has been performed to study the flexural behavior of composite steel joists encased in SFRC. Compressive strength, tensile strength and modulus of rupture are computed. The physical properties of steel fiber reinforced concrete are calculated through testing at the UTA Civil Engineering Laboratory Building. Eighteen cylindrical (4"x8") specimens, eighteen beams encased with Double angle (6"x6"x20"), eighteen beams encased with HSS steel beams (6"x6"x20") were prepared and tested after 28 days of curing. The specimens were tested for their compressive strength, tensile strength, and modulus of rupture. The results showed that compressive strength increased by 45% with adding steel fibers of 1% by volume in concrete. Also, addition of 1% steel fibers by volume increases the tensile strength by 33% as compared to 0% steel fibers by volume. The experimental results showed that, cambering of double angles in concrete beam increases the ultimate load capacity by 10% while midspan deflection reduces by 25% relative to straight section in concrete beam. The study investigates flexural behavior HSS and double angle encased concrete beams, while results shows approximately similar performance for both type of beams. Use of steel fibers reinforced concrete is also an advantage to increase the flexural capacity of beam and to reduction in midspan. Adding 1% volume fraction of steel fibers to increases the ultimate load capacity by 30% and reduces the midspan deflection by 41% comparative to concrete without steel fibers. This study shows that, there is significant improvement in the flexural capacity of beam with the provision of cambering and addition of steel fibers. Preflex Encased steel Joist Composite Beams are innovative structural members that provides more strength to structures with long spans like long span bridges, because it requires girders of large flexural capacity.
Construction Materials And Structures
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Author : S.O. Ekolu
language : en
Publisher: IOS Press
Release Date : 2014-12-05
Construction Materials And Structures written by S.O. Ekolu and has been published by IOS Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-12-05 with Technology & Engineering categories.
The two volumes of these Proceedings contain about 200 conference papers and 10 keynote papers presented at the First International Conference on Construction Materials and Structures, held in Johannesburg, South Africa from 24 to 26 November 2014. It includes sections on Materials and characterization; Durability of construction materials; Structural implications, performance, service life; Sustainability, waste utilization, the environment; and Building science and construction.
Behavior Of Prestressed Concrete Beams With Cfrp Strands
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Author :
language : en
Publisher:
Release Date : 2016
Behavior Of Prestressed Concrete Beams With Cfrp Strands written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Concrete beams categories.
The high cost of repairing reinforced or prestressed concrete structures due to steel corrosion has driven engineers to look for solutions. Much research has been conducted over the last two decades to evaluate the use of Fiber Reinforced Polymers (FRPs) in concrete structures. Structural engineering researchers have been testing FRP to determine their usability instead of steel for strengthening existing reinforced concrete structures, reinforcing new concrete members, and for prestressed concrete applications. The high strength-to-weight ratio of FRP materials, especially Carbon FRP (CFRP), and their non-corrosive nature are probably the most attractive features of FRPs. In this study, an experimental program was conducted to investigate the flexural behavior of prestressed concrete beams pre-tensioned with CFRP strands. The bond characteristics were examined by means of experimentally measuring transfer length, flexural bond length, and bond stress profiles. A total of four rectangular beams pre-tensioned with one 0.5-in. diameter CFRP strand were fabricated and tested under cyclic loading for five cycles, followed by a monotonically increasing load until failure. In investigating bond properties, the experimental results were compared to the equations available in the literature. The results from the four flexural tests showed that the main problem of CFRP strands, in addition to their liner-elastic tensile behavior, was lack of adequate bonding between FRP and concrete. Poor bonding resulted in early failure due to slippage between FRPs and concrete. As a result, a new technique was developed in order to solve the bonding issues and improve the flexural response of CFRP prestressed concrete beams. The new technique involved anchoring the CFRP strands at the ends of the concrete beams using a new "steel tube" anchorage system. It was concluded that the new technique solved the bond problem and improved the flexural capacity by about 46%. A computer model was created to predict the behavior of prestressed beams pre-tensioned with CFRP. The predicted behavior was compared to the experimental results. Finally, the experimental results were compared to the behavior of prestressed concrete beams pre-tensioned with steel strands as generated by the computer model. The CFRP beams showed higher strength but lower ductility.
A Standard Tensile Testing Procedure For Fiber Reinforced Concrete Frc And Ultra High Performance Fiber Reinforced Concrete Uhp Frc Based On Double Punch Test Dpt
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Author : Shuveksha Tuladhar
language : en
Publisher:
Release Date : 2017
A Standard Tensile Testing Procedure For Fiber Reinforced Concrete Frc And Ultra High Performance Fiber Reinforced Concrete Uhp Frc Based On Double Punch Test Dpt written by Shuveksha Tuladhar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Current test methods such as ASTM 1609, ASTM 1550 and direct tensile test are used for evaluating the mechanical properties of Fiber Reinforced Concrete (FRC) and to determine the quality of mixture in design and construction practice. These test methods show high variability in the results, requires large specimen and complicated test setup. An ideal material test method for FRC should give consistent results in determining mechanical properties such as peak strength and residual strengths. Moreover, current test methods are expensive and time-consuming as more specimens are needed to acquire reliable test results. Double Punch Test (DPT) is a simple, reliable and consistent test method for evaluating the post-cracking behavior of FRC. DPT originally developed to determine the tensile strength of plain concrete, can also be used for evaluation of peak load and post-peak behavior of FRC and Ultra-High-Performance Fiber Reinforced Concrete (UHP-FRC). This method has a simple test setup and is easier to conduct in comparison to other test methods. DPT experimental test results are seen to be more consistent than the other test methods currently in practice. The simplicity of test setup, reliability of results (low scatter due to the higher cracking surface) and smaller specimens (fewer materials used) are the major advantages of using DPT method for evaluation of post cracking response of FRC and UHP-FRC. In this research, the application of double punch test is validated for FRC and the same method has been used and developed to confirm the suitability for UHP-FRC material in determining tensile strength and behavior in post cracking phase. However, there still exist some potential issue in the DPT method that needs to be resolved. The circumferential extensometer that is used to determine the total crack opening displacement in DPT is an expensive instrument. This limits the use of DPT method in most of the industrial and research laboratories. The measurement of crack width and inspection of a number of cracks are the important parameter for evaluating the characteristics of any concrete material. It is time-consuming to measure the crack width in a test by conventional visual inspection and automated crack width measurement is indispensable. This research mainly focuses on the deriving a simple formula for estimating average and maximum crack width using the axial deformation data and optimize the time taken for each DPT test. The relation would remove the need of using the expensive circumferential extensometer for the test. Thus, DPT could be used to evaluate and compare the quality of mixture for FRC and UHP-FRC by using a simple arrangement of LVDTs.
Applied Mechanics Reviews
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Author :
language : en
Publisher:
Release Date : 1994
Applied Mechanics Reviews written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with Mechanics, Applied categories.