Behaviour Of Self Consolidating Steel Fiber Reinforced Concrete Beams Under Reversed Cyclic Loading
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Behaviour Of Self Consolidating Steel Fiber Reinforced Concrete Beams Under Reversed Cyclic Loading
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Author : Nima Aghniaey
language : en
Publisher:
Release Date : 2002
Behaviour Of Self Consolidating Steel Fiber Reinforced Concrete Beams Under Reversed Cyclic Loading written by Nima Aghniaey and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with University of Ottawa theses categories.
Concrete is a very weak and brittle material in tension. It has been shown in previous researches that the addition of steel fibers to a concrete matrix can improve this behavior. The ability of fibers to control and redistribute stresses after cracking results in a number of improvements in the structural behaviour of concrete. A review of existing literature shows that the addition of steel fibers enhances concrete's tensile resistance, crack control properties, ductility and damage tolerance. In beams, fibers can transform brittle shear response into a flexural response and promote ductility, thereby allowing for a full or partial replacement of traditional shear reinforcement. The enhanced shear capacity, ductility and damage tolerance of Steel Fiber Reinforced Concrete (SFRC) can also potentially be used to relax seismic detailing requirements in frames by partially replacing the required transverse reinforcement in the plastic hinge regions of RC beams. One of the drawbacks associated with SFRC is that the addition of steel fibers to a traditional concrete mix at high fiber contents can result in workability problems. The combined use of Self-Consolidating Concrete (SCC) and fibers can solve this problem and facilitate placement for a wider range of structural applications. Although several studies have been conducted on the behaviour of SFRC beams subjected to monotonic loading, there is limited research on the behaviour of SFRC beams under cyclic or reverse-cyclic loading. This thesis presents the results of an experimental and analytical study conducted on nine SFRC beam specimens tested under load reversals. The main objective of this research program was to investigate the effect of fibers on structural behaviour and to examine the ability of steel fibers to replace transverse reinforcement. The experimental and analytical results show that use of fibers results in several improvements in behaviour, including enhanced damage tolerance and post-peak ductility. The results also show that steel fibers can potentially be used to allow for a reduction of transverse reinforcement in beams, however further research is required.
Structural Behaviour Of Self Consolidating Steel Fiber Reinforced Concrete Beams
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Author : Michael I. Cohen
language : en
Publisher:
Release Date : 2012
Structural Behaviour Of Self Consolidating Steel Fiber Reinforced Concrete Beams written by Michael I. Cohen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Concrete beams categories.
When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.
Dynamic Properties And Application Of Steel Fiber Reinforced Self Consolidating Concrete To Segmental Bridge Columns In Moderate To High Seismic Regions
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Author : Nasi Zhang
language : en
Publisher:
Release Date : 2014
Dynamic Properties And Application Of Steel Fiber Reinforced Self Consolidating Concrete To Segmental Bridge Columns In Moderate To High Seismic Regions written by Nasi Zhang 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.
In this dissertation, the application of steel fiber reinforced self-consolidating concrete (SFRSCC) to precast unbonded post-tensioned segmental bridge columns in moderate-to-high seismic regions is evaluated numerically and experimentally. Drop weight impact tests are first conducted on plain concrete and steel fiber reinforced concrete (SFRC). The standard drop test recommended by the American Concrete Institute (ACI) is first conducted and a modification to this standard ACI, which involves visual inspection of first cracking and ultimate failure, is then developed. The Kolmogorov-Smirnov (K-S) test along with fitted normal and lognormal distributions are used to examine the distribution of the number of blows required to cause first cracking and ultimate failure of the concrete. The minimum sample size required to calculate the impact strength of SFRC is determined using equations available in the literature. This sample size is used in the subsequent impact study on SFRSCC specimens. The static and dynamic properties of ten groups of SFRSCC, including one group of self-consolidating concrete (SCC) without steel fibers, are studied and compared. Dramix℗ʼ ZP305, RC-65/35-BN, and RC-80/30-BP steel fiber (glued and hooked end) at a volume of 0. 25%, 0. 5% and 1% are considered in the study. The static properties are calculated using compression tests, split-tension tests and flexural beam tests. The dynamic properties are determined using the modified ACI impact test. A dynamic load sensor is installed underneath the base plate of the impact test machine to measure the relative reaction force history. The recorded reaction forces are used to develop an automated impact test method, which can circumvent visual inspections. Two large-scale (1:3. 37), precast, unbonded and post-tensioned segmental columns, one constructed with SCC and one constructed with SFRSCC (with 0. 5% of ZP305 steel fiber by volume), are tested under cyclic loading. These segmental columns incorporate shear keys at the joints. The backbone force-displacement relationships of the segmental columns are calculated from a pushover model available in the literature. The hysteretic behavior of the segmental columns under cyclic loading is also simulated by a numerical model developed on the OpenSEES platform. A single span, large-scale (1:3. 37) bridge model incorporating SFRSCC segmental columns (with 0. 5% of ZP305 steel fiber by volume) is tested on a shake table. Two types of cap beam-to-superstructure connections are considered for the bridge model: a connection using non-seismic rubber bearing and a fixed connection. The bridge model is tested for far field and near field ground motions along various directions and with increasing peak ground accelerations (PGAs). The evolution of the cumulative damage to the bridge model after each seismic test is evaluated through a system identification involving white noise excitation. A flag-shaped hysteretic model is proposed and validated through the cyclic test results obtained in this research and those available in the literature. The proposed flag-shaped model is used to predict the seismic response of the bridge model. Adding steel fibers to concrete significantly improves its impact strength and ductility. The SFRSCC segmental columns suffered less damage than the SCC columns for the same level of drift. The large-scale bridge model incorporating SFRSCC segmental columns sustained high intensity far field and near field ground motions with limited damage. The proposed flag-shaped hysteretic model can be used to simulate the cyclic behavior of segmental columns, and to provide reasonable estimates of their seismic response under strong ground motions.
Behaviour And Analysis Of Steel Fibre Reinforced Concrete Under Reversed Cyclic Loading
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Author : Wei Jun Wei Luo
language : en
Publisher:
Release Date : 2014
Behaviour And Analysis Of Steel Fibre Reinforced Concrete Under Reversed Cyclic Loading written by Wei Jun Wei Luo 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.
Shear Behavior Of Steel Fiber Reinforced Ultra High Strength Self Compacted Concrete Beams
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Author : Omar Jumah Zaal Rawashdeh
language : en
Publisher:
Release Date : 2015
Shear Behavior Of Steel Fiber Reinforced Ultra High Strength Self Compacted Concrete Beams written by Omar Jumah Zaal Rawashdeh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Fiber-reinforced concrete categories.
Ultra-high-strength concrete is a new class of concrete that has been the result of the progress in concrete material science and development. This new type of concrete is characterized with very high compressive strength; about 100 MPa. Ultra-high strength concrete shows very brittle failure behavior compared to normal-strength concrete. Steel fibers will significantly reduce the workability of ultra-high strength concrete. The development and use of self-compacting concrete has provided a solution to the workability issue. The combination of technology and knowledge to produce Ultra-High strength fiber reinforced self-compacting concrete was proved to be feasible. Few studies investigated the effect of incorporating steel fibers on the shear behavior of ultra-high-strength reinforced concrete beams. The research consists of a test series and analytical investigation. The present research investigated the shear behavior of reinforced beams made of normal-strength-concrete fiber-reinforced self-compacting concrete (28 MPa), high-strength concrete fiber-reinforced self-compacting concrete (60 MPa) and ultra-high-strength fiber-reinforced self-compacting concrete (100 MPa). The test parameters included two different shear span-to-depth ratios of 2.22 (deep beam action) and 3.33 (slender beam action), and three different steel fiber volume fractions of 0.4%, 0.8%, and 1.2%. The test results showed that the shear strength gain ranged from 20% to 129% for the beams having a concrete grade of 28 MPa, 26% to 63% for the beams having a concrete grade of 60 MPa, and 8.6% to 94% for the beams with a concrete grade of 100 MPa. For the deep beams, the shear strength gain tended to decrease by increasing the concrete grade. For the slender beams with steel fiber volume fractions of 0.4% and 0.8%, varying the concrete grade had no obvious effect on the shear strength gain. For the viii slender beams with the higher steel fiber volume fraction of 1.2%, the shear strength gain tended to decrease with an increase in the concrete grade. In the analytical investigation, the accuracy and validity of published analytical models have been demonstrated. Predictions of analytical models by Ashour et al. (1992) and Narayanan et al. (1987) were in good agreement with the experimental results.
Nonlinear Analysis Of Reinforced Concrete Beams And Columns With Special Reference To Full Range And Cyclic
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Author : Zhizhou Bai
language : en
Publisher:
Release Date : 2017-01-27
Nonlinear Analysis Of Reinforced Concrete Beams And Columns With Special Reference To Full Range And Cyclic written by Zhizhou Bai and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-27 with categories.
This dissertation, "Nonlinear Analysis of Reinforced Concrete Beams and Columns With Special Reference to Full-range and Cyclic" by Zhizhou, Bai, 白植舟, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled NONLINEAR ANALYSIS OF REINFORCED CONCRETE BEAMS AND COLUMNS WITH SPECIAL REFERENCE TO FULL-RANGE AND CYCLIC BEHAVIOUR Submitted by BAI Zhizhou for the degree of Doctor of Philosophy at The University of Hong Kong in December 2006 In this thesis, the full-range flexural behaviour of reinforced concrete (RC) beams and columns made of normal- and high-strength concrete under both monotonic and cyclic loading is studied. The full-range moment-curvature relationships are obtained based on a numerical method that considers the cyclic response of constitutive materials. A two-dimensional nonlinear finite element procedure is also developed for the analysis of RC beams under monotonic and non-reversed cyclic loading. For RC beam sections, it is found that the full-range flexural behaviour is basically dependent on the tension steel to balanced steel ratio. The full-range moment-curvature curves for under-reinforced sections have long yield plateaus while those for over-reinforced sections have sharp peaks. The full-range moment-curvature curves under monotonic loading in sagging and hogging moments are found to give the envelope for cyclic response. Reversed cyclic loading generally creates overall residual tensile strains in RC sections, and is especially significant for under-reinforced sections. The variation of neutral axis depth during monotonic and cyclic loading shows different trends for under- and over-reinforced sections. For RC column sections, it is found that the full-range flexural behaviour is strongly dependent on the axial load and confinement, which govern the moment capacity, ductility and failure mode of an RC column. The flexural ductility is generally reduced by compressive axial load but increased by confinement. The moment-curvature curve of a section under tensile axial load or relatively low compressive axial load has a long plateau around peak moment, while that under relatively high compressive axial load has a sharper peak. The complete moment-curvature curves under monotonic loading in sagging and hogging moments give the envelope for cyclic response except for sections under very high compressive axial load. A section under tensile axial load or low compressive axial load tends to elongate after a complete cyclic loading, while a section under high compressive axial load tends to shorten. The variations of neutral axis depth and steel stresses are also dependent on the axial load and confinement. The effect of concrete tensile strength is only notable for under-reinforced RC beam sections and for RC column sections under tensile axial load or relatively low compressive axial load at the service stage. The Bauschinger effect of steel is negligible in the case of RC sections undergoing non-reversed cyclic loading, but becomes significant for reversed cyclic loading that is extended into large inelastic deformation. Besides section analyses, a two-dimensional nonlinear finite element procedure is also developed for better understanding of the behaviour of RC beams under monotonic and non-reversed cyclic loading. In particular, the local bond-slip effect is modelled by linear displacement contact elements. The numerical predictions are validated by experimental results. With the proper choice of bond parameters, results show that the procedure is capable of modelling the for
Tensile Behaviour Of Ultra High Performance Steel Fiber Reinforced Concrete
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Author : Yuechen Yang
language : en
Publisher:
Release Date : 2019
Tensile Behaviour Of Ultra High Performance Steel Fiber Reinforced Concrete written by Yuechen Yang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
Reinforcing bars are provided in reinforced concrete structures on account of conventional concretes negligible resistance to tension. However, corrosion of steel reinforcement inevitably occurs due to carbonation and chloride ingress, which significantly reduces the service life of structures. An alternative to this predicament is now feasible with the advent in cementitious material technologies, such as ultra-high-performance, self-consolidating, steel fiber reinforced concrete (UHP-SFRC). The keystone of safe and economically feasible designs with UHP-SFRC is dependant on its characterization in tension. Thus, in the present work, a detailed research study including both experimental and analytical components was conducted to investigate the tensile behaviour of UHP-SFRC: tensile strength was quantified and correlated through direct tension test (DTT), four-point bending test (FPBT), splitting tensile test, nonlinear finite element analysis and a calibrated empirical expression in relation to cylinder compressive strength. In addition, effects of important parameters on flexural strength including casting methodology, volumetric ratio of steel fibers, aspect ratio of bending prism and prism size were assessed. Moreover, the bilinear stress-strain and stress-crack mouth opening relationships of UHP-SFRC were derived according to the inverse analysis procedures proposed by Annex 8.1 of CSA-S6 (2018) and Annex U of CSA-A23.1 (2019). Furthermore, a nonlinear finite element analysis software, VecTor2, was employed to develop numerical models with the ability to match the response curves obtained from FPBT. Analytical results indicated that cracking strength of UHP-SFRC derived from the inverse analysis method was generally greater than those obtained from direct tension test, splitting tensile test, nonlinear finite element models and the calibrated empirical expression. Additionally, inverse analysis and finite element analysis results indicated that the majority of prisms exhibited tension hardening behaviour with a hardening ratio greater than 1.1 and an ultimate tensile strain greater than 0.1%. In addition to tension tests, a host of non-destructive tests were conducted to assess the physical properties and durability performance of UHP-SFRC.
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.
Behavior Of Fiber Reinforced Concrete Encased Open Web Steel Joist Composite Members Under Monotonic And Reversed Cyclic Loading
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Author : Madhusudan Khuntia
language : en
Publisher:
Release Date : 1998
Behavior Of Fiber Reinforced Concrete Encased Open Web Steel Joist Composite Members Under Monotonic And Reversed Cyclic Loading written by Madhusudan Khuntia and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with Composite construction categories.
Fiber Reinforced Concrete Under Cyclic And Dynamic Compressive Loadings
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Author : Duane Eric Otter
language : en
Publisher:
Release Date : 1988
Fiber Reinforced Concrete Under Cyclic And Dynamic Compressive Loadings written by Duane Eric Otter and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with Composite materials categories.