Shear Behavior Of Prestressed Concrete Box Beams Reinforced With Cfrp Stirrups
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Shear Behavior Of Prestressed Concrete Box Beams Reinforced With Cfrp Stirrups
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Author : Omkar D. Karekar
language : en
Publisher:
Release Date : 2011
Shear Behavior Of Prestressed Concrete Box Beams Reinforced With Cfrp Stirrups written by Omkar D. Karekar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Evaluation Of Cfrp Reinforced Prestressed Concrete Beams For Shear Behavior
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Author : Yassin Abbas
language : en
Publisher:
Release Date : 2022
Evaluation Of Cfrp Reinforced Prestressed Concrete Beams For Shear Behavior written by Yassin Abbas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
Fiber-reinforced polymer (FRP) can be effectively utilized in structures as rods, sheets, bars, and tendons due to its high strength-to-weight ratio, non-corrosiveness, non-magnetic properties, and its flexibility. FRPs include carbon fiber-reinforced polymers (CFRPs), aramid fiber-reinforced polymers (AFRPs), and glass fiber-reinforced polymers (GFRPs). Previous studies have investigated these materials under various load conditions and in a variety of structures, including prestressed concrete beams reinforced with CFRP, which has the highest tensile modulus out of all the FRP varieties. The increasing popularity of FRP as a reinforcement particularly as prestressing tendons in concrete structures is prompting research to more accurately predict the behavior of such structures under various types of loading and boundary conditions. Although many studies have investigated the flexural behavior of beams reinforced with FRP, few studies have focused on their complex shear behavior. Design guidelines in the U.S. such as ACI440.4R-04 and AASHTO 2018 have been published to support the design of structures using FRP. The objective of this thesis was to evaluate these guidelines for accuracy in predicting nominal shear capacity using prestressed concrete beams reinforced with CFRP. This study also aimed to offer alternative solutions to improve calculations of nominal shear capacity for prestressed beams reinforced with CFRP tendons.
Shear Strength Of Concrete Beams Prestressed With Cfrp Cables
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Author : Mirpayam Nabipaylashgari
language : en
Publisher:
Release Date : 2012
Shear Strength Of Concrete Beams Prestressed With Cfrp Cables written by Mirpayam Nabipaylashgari 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.
This thesis investigates the shear capacity of concrete T-beams prestressed with CFRP cables (CFCC) and contributes to the scarce research available for shear behavior of FRP prestressed concrete beams. Four beams are tested under distributed load, while twelve beams are tested under four point bending. Three different a/d ratios of 1.5, 2.5 and 3.5 are investigated. The results show that the shear capacity of the beams increases significantly when a/d is reduced below 2.5. The effect of FRP stirrups on the shear capacity of the beams is investigated and it is shown that the minimum required stirrups according to CSA-S6-10 are ineffective in deep beams with a/d = 1.5. The accuracy of current North American shear design formulas for FRP prestressed concrete beams subjected to four-point bending and distributed load is evaluated. The available strut and tie models are studied for determining the shear capacity of FRP prestressed deep beams.
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.
Shear Behavior Of Large Scale Concrete Beams Strengthened With Fibre Reinforced Polymer Frp Sheets
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Author :
language : en
Publisher:
Release Date : 2001
Shear Behavior Of Large Scale Concrete Beams Strengthened With Fibre Reinforced Polymer Frp Sheets written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Many studies conducted on the use of Fibre Reinforced Polymer (FRP) sheets for shear strengthening have been completed on beams that are small in relation to the effective bond length of the FRP. This study focuses on the use of FRP sheets for large-scale concrete members. Two series of large scale concrete beams were strengthened in shear to develop a better understanding of the behaviour of FRP shear strengthening on large specimens and to develop a means of predicting the shear capacity for all sizes of members. The first series of three specimens were obtained from a full sized I-section prestressed concrete bridge girder. One of these specimens was tested as a control, with the remaining two strengthened for shear with different configurations of Carbon Fibre Reinforced Polymer (CFRP) sheets. To develop a better understanding of bond behaviour of large-scale specimens, three reinforced concrete T-section beams were fabricated with a web height that was larger than those found in the literature. One of these beams was strengthened in shear using Glass Fibre Reinforced Polymer (GFRP) sheets and two others were strengthened using CFRP sheets. These beams were tested under static loading conditions. (Abstract shortened by UMI.).
Shear Behavior Of Concrete Beams Reinforced With High Performance Steel Shear Reinforcement
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Author :
language : en
Publisher:
Release Date : 2004
Shear Behavior Of Concrete Beams Reinforced With High Performance Steel Shear Reinforcement written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
The current shear design provisions of the ACI 318 specifications limit the yield strength in transverse reinforcement to 60 ksi. Advancement in technology has led to the fabrication of High Performance steel. Use of HP steel in reinforced concrete could lead to cost savings by reducing the amount of steel required due to the inherited high strength and increase of the service life of structural members due to its enhanced corrosion resistance. This research is undertaken to examine the use of high performance steel as a feasible reinforcement material for reinforced concrete structures. Commercially available steel, Micro-Composite Multi-Structural Formable (MMFX), conforming to ASTM A 1035, was selected for this study. MMFX steel has minimum yield strength of 100 ksi. This experimental program comprised eighteen tests using nine large-scale reinforced concrete beams subjected to static loading up to failure. The key parameters considered in experimental program were the steel type and the amount of shear reinforcement. This research investigated crack width, modes of failure, deflection, stirrup strain, ultimate load carrying capacity and the behavior of the MMFX steel as transverse reinforcement for concrete beams. Results from the experimental program show that by utilizing the higher yield strength and consequently reducing the reinforcement ratio of MMFX steel, the beams can achieve almost the same load-carrying capacity as the beams reinforced with conventional Grade 60 steel. Also, beams reinforced with MMFX showed similar deflections at service load as the beams reinforced with Grade 60 steel. Therefore, reduction in the reinforcement ratio of MMFX steel, did not affect the serviceability of these beams. Analysis shows that the ACI 318, CSA, and AASHTO LRFD design codes can closely predict the ultimate shear strength for beams reinforced with high performance steel having yield strength up to 100 ksi. The beams were also analyzed using a well-established Mo.
Shear Strengthening Of Reinforced Concrete Beams With Bi Directional Carbon Fiber Reinforced Polymer Cfrp Strips And Cfrp Anchors
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Author : Nawaf Khaled Alotaibi
language : en
Publisher:
Release Date : 2014
Shear Strengthening Of Reinforced Concrete Beams With Bi Directional Carbon Fiber Reinforced Polymer Cfrp Strips And Cfrp Anchors written by Nawaf Khaled Alotaibi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The use of externally bounded Carbon Fiber Reinforced Polymer (CFRP) for strengthening existing RC structures has shown promising results. Although CFRP materials have high tensile strength, the ability to utilize that strength is limited by debonding of the CFRP laminates from the concrete surface. In order to prevent or delay debonding, CFRP anchors were used to provide an alternative means of transferring forces from CFRP strips to the concrete. Previous tests on prestressed I-girders strengthened with uni-directional and bi-directional CFRP strips showed that bi-directional CFRP application resulted in significant shear strength gain in comparison to a uni-directional application. The objective of this thesis is to evaluate the behavior of reinforced concrete beams strengthened in shear with bi-directional CFRP strips and CFRP anchors so that the findings from the previous work can be understood and implemented. Four 24 in. deep T-beams were fabricated at the Phil M. Ferguson Structural Engineering Laboratory at The University of Texas at Austin. Eight tests were conducted on these specimens to examine the effect of the bi-directional layout of CFRP on the shear strength. Specimens with 14-in. web width were selected as a part of the experimental program to allow for direct comparison with test results from the previous project. Additional beams with a web width of 8 in. were included to evaluate thinner webs similar to those in the I-girders. Test results indicate a significant increase in shear strength due to the bi-directional application of CFRP strips with CFRP anchors installed on beams with a shear span-to-depth ratio (a/d) of 3. Substantial shear strength gain up to 62% was achieved in beams with 14-in. webs. and up to 43% for beams with 8-in. webs. However, negligible shear strength gain was observed in beams with a/d of 1.5 (deep beams). Experimental test results demonstrate an interaction between the contribution of concrete, transverse steel and CFRP to the shear resistance of a reinforced concrete beam. The findings of this research contribute to a better understanding of the shear behavior of reinforced concrete members strengthened with externally bonded CFRP applied bi-directionally. Experimental results from this research project provide data needed in the field of CFRP shear strengthening since limited data are available on large-scale tests.
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.
Shear Behavior Of Reinforced Concrete T Beams Strengthened With Carbon Fiber Reinforced Polymer Cfrp Sheets And Cfrp Anchors
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Author : Yun Gon Kim
language : en
Publisher:
Release Date : 2011
Shear Behavior Of Reinforced Concrete T Beams Strengthened With Carbon Fiber Reinforced Polymer Cfrp Sheets And Cfrp Anchors written by Yun Gon Kim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The objective of this research is the evaluation of shear behavior of full-scale reinforced concrete T-beams strengthened with carbon fiber reinforced polymer (CFRP) sheets and CFRP anchors. Although the CRFP material has high tensile strength, premature failure due to debonding CFRP sheets prevents utilizing that strength. The use of CFRP anchors prevents this failure, so the CFRP sheets are able to reach ultimate strain. The current shear design is based on plasticity, which assumes that all steel (ductile material) stirrups, across the critical section yield at ultimate. However the strain in the CFRP (brittle material), is essential to estimate the shear contribution of CFRP. To evaluate the validity of CFRP strengthening for shear, 24 tests were conducted with several parameters including shear-span-to-depth ratio, depth of beams, different transverse reinforcement ratios, and the layout of CFRP strips. In addition, a simple shear behavior model was developed to explain the differences between ductile and brittle material. From test observation, the use of CFRP anchors resulted in U-wrap application to perform like continuous wrapping which implies that a CFRP strip reached rupture strain because the anchors prevented debonding failure. However, all FRP strips did not rupture simultaneously because the strain distribution across a critical crack was not uniform. The average strain across the critical crack was about 0.005. Therefore a conservative value of effective strain (0.004) was selected for design purposes. In addition, when a beam is strengthened with CFRP, interactions between the contributions of the CFRP, steel or concrete must be taken into account. Factors ka, ks, and kf were introduced in the proposed shear design equations. Factor ka reflects the change in the material contributions as the shear span to depth ratio (a/d ratio) changes in deep beams. Factors ks and kf account for the change in steel or CFRP shear contribution due to the change in the critical crack angle as well as the interactions between the steel and FRP transverse reinforcement. As the amount of either steel or FRP material increase, the efficiency of the other material decreases.
Shear Capacity Of Prestressed Concrete Beams Reinforced With Frp Reinforcement
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Author : Daniel Mal Bok Dowden
language : en
Publisher:
Release Date : 1997
Shear Capacity Of Prestressed Concrete Beams Reinforced With Frp Reinforcement written by Daniel Mal Bok Dowden and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with Fiber-reinforced plastics categories.