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Book Behavior of Circular Concrete Columns Reinforced with FRP Bars and Stirrups

Download or read book Behavior of Circular Concrete Columns Reinforced with FRP Bars and Stirrups written by Mohammad Afifi and published by . This book was released on 2013 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: The behavior of concrete members reinforced with fiber reinforced polymer (FRP) bars has been the focus of many studies in recent years. Nowadays, several codes and design guidelines are available for the design of concrete structures reinforced with FRP bars under flexural and shear loads. Meanwhile, limited research work has been conducted to examine the axial behavior of reinforced concrete (RC) columns with FRP bars. Due to a lack of research investigating the axial behavior of FRP reinforced concrete columns, North American codes and design guidelines do not recommend using FRP bars as longitudinal reinforcement in columns to resist compressive stresses. This dissertation aims at evaluating the axial performance of RC compression members reinforced with glass FRP (GFRP) and carbon FRP (CFRP) bars and stirrups through experimental and analytical investigations. A total of twenty seven full scale circular RC specimens were fabricated and tested experimentally under concentric axial load. The 300 mm diameter columns were designed according to CAN/CSA S806-12 code requirements. The specimens were divided to three series; series I contains three reference columns; one plain concrete and 2 specimens reinforced with steel reinforcement. Series II contains 12 specimens internally reinforced with GFRP longitudinal bars and transverse GFRP stirrups, while series III includes specimens totally reinforced with CFRP reinforcement. The experimental tests were performed at the structural laboratory, Faculty of Engineering, University of Sherbrooke. The main objective of testing these specimens is to investigate the behavior of circular concrete columns reinforced with GFRP or CFRP longitudinal bars and transverse hoops or spirals reinforcement. Several parameters have been studied; type of reinforcement, longitudinal reinforcement ratio, the volumetric ratios, diameters, and spacing of spiral reinforcement, confinement configuration (spirals versus hoops), and lap length of hoops. The test results of the tested columns were presented and discussed in terms of axial load capacity, mode of failure, concrete, longitudinal, and transverse strains, ductility, load/stress-strain response, and concrete confinement strength through four journal papers presented in this dissertation. Based on the findings of experimental investigation, the GFRP and CFRP RC columns behaved similar to the columns reinforced with steel. It was found that, FRP bars were effective in resisting compression until after crushing of concrete, and contributed on average 8% and 13% of column capacity for GFRP and CFRP RC specimens, respectively. Also, the use of GFRP and CFRP spirals or hoops according to the provisions of CSA S806-12 yielded sufficient restraint against the buckling of the longitudinal FRP bars and provided good confinement of the concrete core in the post-peak stages. The axial deformability (ductility) and confinement efficiency can be better improved by using small FRP spirals with closer spacing rather than larger diameters with greater spacing. It was found that, ignoring the contribution of FRP longitudinal bars in the CAN/CSA S806-12 design equation underestimated the maximum capacity of the tested specimens. Based on this finding, the design equation is modified to accurately predict the ultimate load capacities of FRP RC columns. New factors [alpha][indice inférieur g] and [alpha][indice inférieur c] were introduced in the modified equation to account for the GFRP and CFRP bars compressive strength properties as a function in their ultimate tensile strength. On the other hand, proposed equations and confinement model were presented to predict the axial stress-strain behavior of FRP RC columns confined by FRP spirals or hoops. The model takes into account the effect of many parameters such as; type of reinforcement, longitudinal reinforcement ratio; transverse reinforcement configuration; and the volumetric ratio. The proposed model can be used to evaluate the confining pressure, confined concrete core stress, corresponding concrete strain, and stress-strain relationship. The results of analysis using the proposed confinement model were compared with experimental database of twenty four full-scale circular FRP RC columns. A good agreement has been obtained between the analytical and experimental results. Proposed equations to predict both strength and stress-strain behavior of confined columns by FRP reinforcements demonstrate good correlation with test data obtained from full-scale specimens.

Book Behaviour of GFRP Reinforced Concrete Columns Under Combined Axial Load and Flexure

Download or read book Behaviour of GFRP Reinforced Concrete Columns Under Combined Axial Load and Flexure written by Arjang Tavassoli and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Flexural ductility of prestressed concrete enhancement by lateral confinement

Download or read book Flexural ductility of prestressed concrete enhancement by lateral confinement written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 1992-09-01 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Application of the LRFD Bridge Design Specifications to High strength Structural Concrete

Download or read book Application of the LRFD Bridge Design Specifications to High strength Structural Concrete written by S. H. Rizkalla and published by Transportation Research Board. This book was released on 2007 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores recommended revisions to the American Association of State Highway and Transportation Officials' Load and Resistance Factor Design (LRFD) Bridge Design Specifications to extend the applicability of the flexural and compression design provisions for reinforced and prestressed concrete members to concrete strengths greater than 10 ksi.

Book Modeling the Behavior of Lightly Reinforced Concrete Columns Subjected to Lateral Loads

Download or read book Modeling the Behavior of Lightly Reinforced Concrete Columns Subjected to Lateral Loads written by Eric John Setzler and published by . This book was released on 2005 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Prior studies have shown that many reinforced concrete buildings located in seismically active regions do not have the necessary lateral strength and ductility to perform adequately in earthquakes. In particular, it has been noted that reinforced concrete columns with poor transverse reinforcement are susceptible to shear failure and loss of axial capacity under cyclic lateral loads. The research reported here is focused on modeling the lateral deformation behavior of lightly reinforced concrete columns subjected to lateral loads. Lateral deformations in a column are comprised of three parts: flexural, reinforcement slip, and shear deformations. The monotonic response for each of these deformations was modeled separately. Flexural deformations were modeled using moment-curvature analysis and a plastic hinge model. A review of existing models for reinforcement slip was completed, and an existing model was modified based on experimental data and a parametric study. A comparison of models showed that the proposed slip model performs well in terms of accuracy and efficiency. A shear model was adopted from a previous study, and combined with an available computer program to predict shear behavior in this study. These three component models were found to predict the lateral response envelopes acceptably well for several sets of experimental data. A model for the overall lateral force-deformation relationship of reinforced concrete columns was created by combining the effects of each of the component models. The behavior of a column is classified into one of five categories based on a comparison of the shear, yield, and flexural strengths. The expected behavior in each category determines rules that govern the combination of the deformation components. For columns that are susceptible to shear failure after the onset of flexural failure, the response envelope is modified based on an available shear capacity model. An axial capacity model is also employed for the prediction of ultimate deformations. The proposed model was compared with experimental data from 37 column tests by various researchers. It was found that the classification system employed in the model was successful in representing column behavior. Overall, the model did a reasonable job of predicting the lateral response envelope for the columns in the test database. The model predicted the peak lateral strength well, and successfully represented the onset of shear failure in columns initially failing in flexure.

Book Behavior of Concrete and Slender Reinforced Concrete Columns Under Cyclic Axial Compression with Bidirectional Eccentricities

Download or read book Behavior of Concrete and Slender Reinforced Concrete Columns Under Cyclic Axial Compression with Bidirectional Eccentricities written by Byong Youl Bahn and published by . This book was released on 1993 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: A rational analysis of reinforced concrete (R/C) structures requires satisfactory modeling of the behavior of concrete under general loading patterns. The behavioral characteristics of concrete dominantly depends upon its load history. For the study of concrete behavior, parametric study and experimental investigation into the behavior of concrete under load history of random cycles are performed. Through parametric study, the applicability of the previous concrete models is examined and a physically motivated modeling for the cyclic stress-strain relationships is proposed. The present modeling of concrete under general cyclic loading is initiated to provide substantial applicability, flexibility of mathematical expressions and furthermore to describe the behavior of random cycles. For the experimental study of concrete subjected to cyclic axial compressions, tests of 3 in. by 6 in. concrete cylinders are conducted under four different loading regimes to determine the major experimental parameters for the proposed analytical expressions. The model developed is based on the results of parametric study and experimental data obtained for the present study. The validity of the proposed general cyclic model is confirmed through a comparison of the experimental results and simulated behavior of the model. Furthermore, the analytical model proposed has been idealized and incorporated into the procedures in analyzing RIC columns. The behavior of R/C columns having various properties and subjected to a variety of loading conditions have been the topics of considerable investigation. Of particular significance in the area of unexplored problems is the behavior of R/C columns under cyclic compressive load. It should be noted that cyclic loads with bidirectional eccentricities considered are in the longitudinal direction, and not in the transverse direction, with respect to the column axis. For the experimental investigation, tests of four foot long columns are conducted under stroke control to achieve both ascending and descending branches of the load-deformation curves. Analysis of RC columns subjected to cyclic axial compressions with bidirectional eccentricities should be approached from the standpoint of a three dimensional problem. A numerical procedure based on extended finite segment method is proposed here to predict the ultimate load, deflections and moment-curvature of experimental results. It is found that the proposed numerical analysis can reasonably simulate the loading and unloading behavior of R/C columns under combined biaxial bending moments and axial compressions.

Book Flexural Behavior of Lightweight Concrete Columns Under Seismic Conditions

Download or read book Flexural Behavior of Lightweight Concrete Columns Under Seismic Conditions written by Mervyn J. Kowalsky and published by . This book was released on 1996 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Behavior of Non Ductile Slender Reinforced Concrete Columns Retrofit by CFRP Under Cyclic Loading

Download or read book Behavior of Non Ductile Slender Reinforced Concrete Columns Retrofit by CFRP Under Cyclic Loading written by and published by . This book was released on 2019 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Middle East region and many countries in the world, older reinforced concrete (RC) columns are deemed to be weak in seismic resistance because of their low amount of reinforcement, low grades of concrete, and large spacing between the transverse reinforcement. The capacity of older RC columns that are also slender is further reduced due to the secondary moments. Appropriate retrofit techniques can improve the capacity and behavior of concrete members. In this study, externally bonded Carbon Fiber Reinforced Polymer (CFRP) retrofit technique was implemented to improve the behavior of RC columns tested under constant axial load and cyclic lateral load. The study included physical testing of five half-scale slender RC columns, with shear span to depth ratio of 7. Three specimens represented columns in a 2-story, and two specimens represented columns in a 4-story building. All specimens had identical cross sections, reinforcement detail, and concrete strength. Two specimens were control, two specimens were retrofit with CFRP in the lateral direction, and one specimen retrofit in the longitudinal and lateral directions. A computer model was created to predict the lateral load-displacement relations. The experimental results show improvement in the retrofit specimens in strength, ductility, and energy dissipation. The effect of retrofitting technique applied to two full-scale prototype RC buildings, a 2-story and a 4-story building located in two cities in Iraq, Baghdad, and Erbil, was determined using SAP2000.

Book Reinforced Concrete Column Behavior Under Cyclic Loading

Download or read book Reinforced Concrete Column Behavior Under Cyclic Loading written by 熊朝暉 and published by . This book was released on 2017-01-28 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Reinforced Concrete Column Behavior Under Cyclic Loading" by 熊朝暉, Zhaohui, Xiong, 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. DOI: 10.5353/th_b3124383 Subjects: Columns, Concrete Axial loads Reinforced concrete

Book Normal strength and High strength Concrete Columns Under Cyclic Axial Load and Biaxial Moment

Download or read book Normal strength and High strength Concrete Columns Under Cyclic Axial Load and Biaxial Moment written by Mehdi Zarei and published by . This book was released on 2016 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: The technique of using Carbon Fiber Reinforced Polymer (CFRP) materials to repair and strengthen various concrete members has become popular in the structural retrofitting field as an effective way to enhance the strength and ductility of concrete members due to its superior mechanical properties. In this study a method was introduced to study the behavior of concrete columns with and without CFRP jackets under constant axial load and variable lateral load. The lateral load was applied monotonically and cyclically. To predict the behavior of concrete columns under monotonic and cyclic compressive loadings, a computer code was developed to produce the moment-curvature diagram for concrete sections. The moment-curvature diagram was then input in SAP2000 to study the behavior of reinforced concrete columns. The result of this analysis was found to correlate with experimental data well. The behavior of high-strength concrete (HSC) columns having various properties and subjected to a variety of loading conditions has been the topic of considerable investigation. Of particular significance in this area is the behavior of HSC columns under cyclic compressive load with bidirectional eccentricity. For the experimental investigation, tests of six square slender HSC columns were conducted under stroke control to achieve both ascending and descending branches of the load-deformation curves. Analysis of HSC columns subjected to cyclic axial compression with bidirectional eccentricity was approached from the standpoint of a three-dimensional problem. A computer program based on the extended finite segment method and accounting for geometrical nonlinearity has been proposed here to predict the load-deflection curves of HSC columns under cyclical loading. The HSC stress-strain relationship obtained by parametric study and experimental investigation into the behavior of concrete under cyclical load history has been incorporated into the numerical procedure. The presented computer analysis results have been compared with the experimental data, and a satisfactory agreement was attained for both the ascending and descending branches of the load-deformation curves.

Book Behavior of Spirally Reinforced High Strength Concrete Columns Under Axial Loading

Download or read book Behavior of Spirally Reinforced High Strength Concrete Columns Under Axial Loading written by David L. Montgomery and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted to study the behavior of spirally reinforced high strength concrete (HSC) columns subjected to axial compression loading. The main objective of the experiment was to investigate the effects of the volumetric ratio of spiral steel, the spiral spacing, the specimen size and the concrete strength on the strength and ductility performance of confined concrete. Behavior of the cover concrete, spiral reinforcement steel, and longitudinal reinforcing bars were also investigated to gain insight into the overall behavior of HSC columns. A total of 32 spirally reinforced HSC columns were tested, including ten 254 mm diameter columns with concrete strength f'c of 69.7 Mpa, nine 203 mm diameter columns with concrete strength f'c of 69.7 MPa, and thirteen 203 mm diameter columns with concrete strength f 'c of 89.8 MPa. Overall height of each specimen was four times the diameter. All of the specimens were reinforced longitudinally with five deformed reinforcement bars and laterally by various amounts of spiral reinforcement. An increase in the volumetric ratio of spiral steel resulted in increases in the strength and ductility of confined HSC, with the improvements in ductility being more pronounced. Reductions in spiral spacing resulted in improved strength and ductility of confined HSC when the volumetric ratio of spiral steel was sufficiently large. Increases in concrete strength were found to result in decreases in the peak strength enhancement, axial strain at peak strength, spiral stress at peak strength, and deformability of the specimens. Larger diameter columns achieved better participation of the cover concrete shell and had larger strengths at low axial strains. Cover concrete began spalling at lower concrete strengths and at earlier axial strains than expected in the columns with f'c of 89.8 MPa.