An Analysis of Existing Data on Reinforced Concrete Columns PDF Download
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Author: Joseph Daleda
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Joseph Daleda
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Fatemeh Shirmohammadi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Accurate and realistic assessment of the performance of columns in general, and those in critical locations that may cause progressive failure of the entire structure, in particular, is significantly important. This performance is affected by the load history, pattern, and intensity. Current design code does not consider the effect of load pattern on the load and displacement capacity of columns. A primary research sponsored by Kansas Department of Transportation (KDOT) was conducted as the initial step of the present study (No. K-TRAN: KSU-11-5). The main goals of the KDOT project were: (1) investigation of new KDOT requirements in terms of the column design procedure and detailing and their consistency with AASHTO provisions; (2) verification of the KDOT assumptions for the plastic hinge regions for columns and bridge piers, (3) provide assessment of the load capacity of the existing columns and bridge piers in the light of the new specifications and using the new load demand as in the new provisions; and finally recommendations for columns and bridge piers that do not meet the new requirements. A conclusion was drawn that there is a need for conducting more studies on the realistic performance of Reinforced Concrete (RC) sections and columns. The studies should have included performance of RC members under various loading scenarios, assessment of columns capacity considering confinement effect provided by lateral reinforcement, and investigation on performance of various monotonic and cyclic material models applied to simulate the realistic performance. In the study reported here, monotonic material models, cyclic rules, and plastic hinge models have been utilized in a fiber-based analytical procedure, and validated against experimental data to simulate behavior of RC section under various loading scenarios. Comparison of the analytical predictions and experimental data, through moment-curvature and force-deflection analyses, confirmed the accuracy and validity of the analytical algorithm and models. The performance of RC columns under various axial and lateral loading patterns was assessed in terms of flexural strength and energy dissipation. FRP application to enhance ductility, flexural strength, and shear capacity of existing deficient concrete structures has increased during the last two decades. Therefore, various aspects of FRP-confined concrete members, specifically monotonic and cyclic behavior of concrete members confined and reinforced by FRP, have been studied in many research programs, suggesting various monotonic models for concrete confined by only FRP. Exploration of existing model performances for predicting the behavior of several tested specimens shows a need for improvement of existing algorithms. The model proposed in the current study is a step in this direction. FRP wrapping is typically used to confine existing concrete members containing conventional lateral steel reinforcement (tie/spiral). The confining effect of lateral steel reinforcement in analytical studies has been uniquely considered in various models. Most models consider confinement due to FRP and ignore the effect of conventional lateral steel reinforcement. Exploration of existing model performances for predicting the behavior of several tested specimens confined by both FRP and lateral steel shows a need for improvement of existing algorithms. A model was proposed in this study which is a step in this direction. Performance of the proposed model and four other representative models from literature was compared to experimental data from four independent databases. In order to fulfill the need for a simple, yet accurate analytical tool for performance assessment of RC columns, a computer program was developed that uses relatively simple analytical methods and material models to accurately predict the performance of RC structures under various loading conditions, including cyclic lateral displacement under a non-proportionally variable axial load (Esmaeily and Xiao 2005, Esmaeily and Peterman 2007). However, it was limited to circular, rectangular, and hollow circular/rectangular sections and uniaxial lateral curvature or displacement. In this regards, a computer program was developed which is the next generation of the aforesaid program with additional functionality and options. Triangulation of the section allows opportunity for cross-sectional geometry. Biaxial lateral curvature/displacement/force combined with any sequence of axial load provides opportunity to analyze the performance of a reinforced concrete column under any load and displacement path. Use of unconventional reinforcement, such as FRP, in lateral as well as longitudinal direction is another feature of this application.
Author: David Redekop
Publisher:
ISBN:
Category :
Languages : en
Pages : 306
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Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
ISBN: 2883940991
Category : Technology & Engineering
Languages : en
Pages : 73
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For the ongoing condition assessment of concrete structures, it is necessary to identify the extent, nature, cause and prognosis of any deterioration using a range of tools and methods, including prediction models. Combined with the original design and construction details, this gives a vast amount of information over a long time period. A framework concept is therefore needed to process the entirety of the information in order to make sound investment decisions on future maintenance management. To provide such a framework, fib Bulletin 59 summarizes information published infib Bulletins 17, 22, 34 and 44 relevant to the control and assessment of reinforced concrete structures, and develops a practical concept of how, when and where to control the condition of an existing concrete structure in order to facilitate structural management. Thus it gives a basis for processing relevant information in order to make decisions on the appropriate course of action for condition control.
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
ISBN: 2883941025
Category : Technology & Engineering
Languages : en
Pages : 482
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Book Description
The third edition of the Structural Concrete Textbook is an extensive revision that reflects advances in knowledge and technology over the past decade. It was prepared in the intermediate period from the CEP-FIP Model Code 1990 (MC90) tofib Model Code for Concrete Structures 2010 (MC2010), and as such incorporates a significant amount of information that has been already finalized for MC2010, while keeping some material from MC90 that was not yet modified considerably. The objective of the textbook is to give detailed information on a wide range of concrete engineering from selection of appropriate structural system and also materials, through design and execution and finally behaviour in use. The revised fib Structural Concrete Textbook covers the following main topics: phases of design process, conceptual design, short and long term properties of conventional concrete (including creep, shrinkage, fatigue and temperature influences), special types of concretes (such as self compacting concrete, architectural concrete, fibre reinforced concrete, high and ultra high performance concrete), properties of reinforcing and prestressing materials, bond, tension stiffening, moment-curvature, confining effect, dowel action, aggregate interlock; structural analysis (with or without time dependent effects), definition of limit states, control of cracking and deformations, design for moment, shear or torsion, buckling, fatigue, anchorages, splices, detailing; design for durability (including service life design aspects, deterioration mechanisms, modelling of deterioration mechanisms, environmental influences, influences of design and execution on durability); fire design (including changes in material and structural properties, spalling, degree of deterioration), member design (linear members and slabs with reinforcement layout, deep beams); management, assessment, maintenance, repair (including, conservation strategies, risk management, types of interventions) as well as aspects of execution (quality assurance), formwork and curing. The updated textbook provides the basics of material and structural behaviour and the fundamental knowledge needed for the design, assessment or retrofitting of concrete structures. It will be essential reading material for graduate students in the field of structural concrete, and also assist designers and consultants in understanding the background to the rules they apply in their practice. Furthermore, it should prove particularly valuable to users of the new editions of Eurocode 2 for concrete buildings, bridges and container structures, which are based only partly on MC90 and partly on more recent knowledge which was not included in the 1999 edition of the textbook.
Author: Ka-Wai Lee
Publisher: Cuvillier Verlag
ISBN: 3865370497
Category :
Languages : en
Pages : 222
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Author: Richard Lawrence Emberley
Publisher:
ISBN:
Category :
Languages : en
Pages : 456
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Abstract: Fire is a significant threat to the structural integrity of buildings. Depending on the architecture of the structure and the intensity and duration of the fire event, structural members may lose strength and stiffness eventually leading to collapse whether by flexural buckling or crushing. The focus of this research is on the behavior and fire performance of reinforced-concrete columns under fire conditions. In order to effectively study column performance with differing loading, aggregate and dimensional characteristics under varying time-temperature curves and fire exposures, a numerical model was constructed in Microsoft Excel. The spreadsheet model allowed for complete transparency of the calculations and provided a means to visualize the data in flexible ways. ANSYS and several published column furnace tests were used to benchmark the heat transfer and structural analysis portions of the model. One, three and four-sided fire exposures along with the ASTM E119 fire curve and a natural fire curve were used to study latent heating effects, increasing and decreasing eccentricities, moment magnification, and failure modes. Assessments of column structural capacity were performed in accordance with the provisions of ACI 318. The completed model served as an effective tool for the thesis and is available to help aid students and engineers investigate the design of reinforced concrete columns under fire conditions through integration the heat transfer analyses and the structural evaluations.
Author: R. H. Basappa Setty
Publisher:
ISBN:
Category : Columns, Concrete
Languages : en
Pages : 130
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Book Description
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.
Author: Xenia Rofes
Publisher:
ISBN:
Category : Columns, Concrete
Languages : en
Pages : 392
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Author: Eric John Setzler
Publisher:
ISBN:
Category : Columns, Concrete
Languages : en
Pages : 404
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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.
