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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.

Book Spirally reinforced High strength Concrete Columns

Download or read book Spirally reinforced High strength Concrete Columns written by Salvador Martinez Morales and published by . This book was released on 1983 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Behavior of High Strength Concrete Columns

Download or read book Behavior of High Strength Concrete Columns written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of high-strength concrete for bridges and high-rise buildings become popular due to development in concrete technology and availability of various types of mineral and chemical admixtures. High-strength concrete could lead to smaller member sizes for compression members and therefore provide considerable savings associated with material costs and reduction of dead loads. However, Most of the current design codes, such as AASHTO-LRFD Bridge Specifications, are still based on tests conducted using normal-strength concrete. Many studies indicate that the behavior of columns with high-strength concrete is different from that of normal-strength concrete. The experimental phase of this investigation consists of thirty two rectangular and twenty four circular columns subjected to concentric and eccentric loading conditions to investigate the behavior of high-strength concrete columns. The main variables considered in this study were concrete strength ranging from 7.9 to 16.5 ksi, shape of cross section, and longitudinal and transverse reinforcement ratios. Using the test results of this study and other researches in literature, the dissertation provides design equation to predict the capacity of high-strength concrete columns with tie and spiral reinforcements subjected to concentric and eccentric loading conditions up to 18 ksi. The research also proposes a new stress-strain relationship of high-strength concrete confined with spiral reinforcements.

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 Strength of High Strength Concrete Columns Under Eccentric Compression

Download or read book Strength of High Strength Concrete Columns Under Eccentric Compression written by R. H. Basappa Setty and published by . This book was released on 1995 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research work involved a study of behaviour and strength of eccentrically loaded High Strength Concrete columns. The research comprised experimental and analytical components. With regard to experimental work, twelve columns were manufactured and tested to failure. All columns were rectangular in cross-section with 300 mm x 100 mm as dimensions. The test specimens were loaded about the minor axis. The ratio of longitudinal reinforcement was either 1.47% (4 - 12 mm diameter bars) or 2.2% (6 - 12 mm diameter bars). The lateral reinforcement was in the form of rectangular closed ties made of 6 mm wires (W6). The spacing of ties was generally 50 mm, but, was decreased to 30 mm, at either ends to avoid premature failure.

Book Behaviour of High Strength Concrete Columns Under Axial Load and Uniaxial Bending

Download or read book Behaviour of High Strength Concrete Columns Under Axial Load and Uniaxial Bending written by Natalie Anne Lloyd and published by . This book was released on 1994 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to significant economic and structural advantages associated with the use of high strength concrete in compression members, the application of high strength concrete in columns and core walls is increasing. The advantages of using high strength concrete are well documented. Utilisation of high strength concrete leads to a reduction in column size. However, this results in an increase in slenderness of columns which would otherwise be stocky when built using low strength concrete. In addition, columns are rarely designed for pure axial load yet most research to date has focussed on high strength colurnns subject to concentric compression. Very limited data is available on columns subject to eccentric compression. The present research therefore focussed on slender columns subject to eccentric compression.

Book Design of Concrete Structures Using High strength Steel Reinforcement

Download or read book Design of Concrete Structures Using High strength Steel Reinforcement written by Bahram M. Shahrooz and published by Transportation Research Board. This book was released on 2011 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Report 679: Design of Concrete Structures Using High-Strength Steel Reinforcement evaluates the existing American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications relevant to the use of high-strength reinforcing steel and other grades of reinforcing steel having no discernible yield plateau. The report also includes recommended language to the AASHTO LRFD Bridge Design Specifications that will permit the use of high-strength reinforcing steel with specified yield strengths not greater than 100 ksi. The Appendixes to NCHRP Report 679 were published online.

Book The Failure of Plain and Spirally Reinforced Concrete in Compression

Download or read book The Failure of Plain and Spirally Reinforced Concrete in Compression written by Frank Erwin Richart and published by . This book was released on 1929 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Square High strength Concrete Columns Under Load Reversals

Download or read book Behaviour of Square High strength Concrete Columns Under Load Reversals written by Wojciech Lipien and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Strength and deformation characteristics of 10 square confined high-strength concrete columns were investigated. Properties of columns were selected to allow assessment of the importance of confinement parameters for high-strength concrete columns. The specimens were tested under constant axial compression and incrementally increasing lateral deformation reversals, simulating seismic action. The data indicate that high-strength concrete columns can be confined to behave in a ductile manner. The volumetric ratio of confinement reinforcement required for high strength concrete columns is higher than that required for normal-strength concrete columns, although the spacing requirement does not appear to be a function of concrete strength. Columns confined with higher grade lateral reinforcement require lower volumetric ratios of confinement steel. The arrangement of lateral reinforcement plays an important role on improving deformability. Columns confined with well-distributed longitudinal reinforcement, laterally supported by transverse reinforcement show improved deformability. The volumetric ratio and spacing limitations for these columns need not be as stringent as those required for less favourable steel arrangements. Axial compression reduces column ductility. An analytical investigation was also conducted to assess the applicability of conventional analyses techniques used for normal-strength concrete columns to those made with high-strength concrete. The applicability of a confinement model, based on test data under concentric compression, was verified against experimental data. The results indicate that the confinement model can be employed to columns under combined bending and axial load. Furthermore, moment-curvature relationships obtained by plane section analysis, moment-rotation and force-displacement relationships obtained by integration of curvatures and consideration of column plastic hinging region, as usually done for columns with normal-strength concrete, produce fairly accurate representation of experimentally observed force-deformation relationships. (Abstract shortened by UMI.).