Author: Hyerin Lee
Publisher:
ISBN:
Category : Columns, Concrete
Languages : en
Pages : 351

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Author: Hyerin Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 708

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Book Description
The effect of vertical excitation on shear strength of reinforced concrete (RC) columns has been investigated by various researchers. Field evidences, analytical studies and static or hybrid simulations suggested that excessive tension or tensile strain of the column may lead to shear degradation, and that vertical excitation can be one of the causes of shear failure. The published literature lacks dynamic experiments to investigate the effect of vertical excitation on the shear strength of RC columns due to limitations of testing facility. Considering that current seismic codes do not have a consensus on the effect of vertical acceleration on the shear demand and capacity, the presented dynamic tests and accompanying analytical investigation contribute to better understanding of the effect of vertical excitation on shear failure, one of the most critical brittle failure mechanisms. This dissertation provides the experimental and computational results, which confirm that the vertical acceleration can induce shear strength degradation of RC columns. Dynamic tests of two reduced geometrical scale specimens were conducted on the UC-Berkeley shaking table at Richmond Field Station. The two specimens had different transverse reinforcement ratio. As a result of an analytical investigation and preliminary fidelity tests, 1994 Northridge earthquake acceleration recorded at the Pacoima Dam was selected as an input motion among the 3,551 earthquake acceleration records in the PEER NGA database. The chosen ground motion was applied to the test specimens at various levels ranging from 5% to 125%. The specimens were subjected to combinations of the vertical component and the larger of the two horizontal components of the selected ground motion record. For the 125%-scale, not only combined vertical and horizontal motion was applied but also a single horizontal component was considered for direct evaluation of the effect of the vertical excitation. The experimental results imply that vertical acceleration has the potential to degrade the shear capacity of RC columns. The peak shear force in the 125%-scale run with only the horizontal component was larger than that in the 125%-scale runs with the horizontal and vertical components for each specimen, where the peak force was determined by the shear strength at these high-level tests. For these runs, considerable tensile forces were induced on the tested columns due to the vertical excitation. Tension in the columns resulted in degradation of the shear strength, which is mainly due to the degradation of the concrete contribution to the shear strength. Flexural damage at the top of the column took place before the flexural damage at the base since the bending moment at the top was larger. This was a result of the large mass moment of inertia and rigid body rotation of the mass blocks at the top of the column. In addition, comparison of the bending moment histories at the base and top of the two test specimens indicated that they were opposite in sign during the strong part of the excitation of all the intensity levels suggesting that the columns were in double-curvature. As a result of flexural yielding at the top and base of the column when bending in double curvature, the shear force reached the shear capacity which would not take place if yielding occurred only at the base. Consequently, shear cracks took place and extended over the entire column height as the intensity increased especially under the presence of significant axial tension. The analytical investigation also revealed that considerable axial tension forces can be induced in RC columns which resulted in degradation in the shear strength. Two types of computational models were utilized in the computational platform, OpenSees. Models A and B had a beam with hinges element and a nonlinear beam-column element, respectively. In addition, a new shear spring element was implemented in the same computational platform to employ code-based shear strength estimation. The element incorporates the shear strength estimations based on ACI or Caltrans SDC equations addressing the effect of column axial load and displacement ductility. Each of the models A and B was developed both without and with the newly-developed shear spring element. Upon improved modeling, results from the analysis of the tested specimens were examined in terms of shear strength variation. Accordingly, current code equations and the corresponding computational models were evaluated. The models without the shear springs did not capture the shear strength degradation accurately, whereas those including the ACI and Caltrans SDC shear springs captured the shear strength degradation due to the axial tension. Both of the ACI and Caltrans SDC springs provided results on the conservative side, where the ACI shear spring predictions were closer to the experimental results than those of the Caltrans SDC shear spring. Elimination of the concrete contribution to the shear strength under any tension was the main reason for the highly conservative predictions of the Caltrans SDC shear strength equation where the strength reduction caused by ductility was not as significant as that by the axial tension force.

Author: Cole C. McDaniel
Publisher:
ISBN:
Category :
Languages : en
Pages : 232

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Author: Marvin E. Criswell
Publisher:
ISBN:
Category : Columns, Concrete
Languages : en
Pages : 434

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The objectives of this investigation were to study the strength and behavior of slowly (statically) loaded reinforced concrete slab-column connections and to determine the effect of rapid (dynamic) loading on the strength and behavior by comparison with the static test results. Nineteen full-scale models of a connection and adjoining slab area, consisting of a simply supported slab 84 or 94 inches square and 6-1/2 inches thick loaded concentrically on a 10- or 20-inch-square stub column at the center of the slab, were tested. The main variables were the amounts of reinforcement in the slab (p = 0.75 and 1.50 percent), the column size, and the loading speed. Eight specimens were loaded to failure statically, two were subjected to a very rapidly applied load of short duration, and nine were loaded to failure by a rapidly applied load with a rise time chosen to represent the conditions in a blast-loaded structure. The static test results are compared with 12 shear strength prediction methods. Differences between the mechanism of shear failure in slabs and beams are examined. (Author).

Author: Christian Meyer
Publisher: Springer
ISBN: 3709125243
Category : Technology & Engineering
Languages : en
Pages : 257

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Book Description
A comprehensive review of the material behavior of concrete under dynamic loads, especially impact and impuls, opens the volume. It is followed by a summary of the various analytical tools available to engineers interested in analyzing the nonlinear behavior of reinforced concrete members for dynamic load. These range from relatively simple and practice-oriented push-over analysis to sophisticated layered finite element models. Important design-related topics are discussed, with special emphasis on performance of concrete frames subjected to seismic loads. The significance of modern software systems is recognized by including extensive examples. For readers not current in dynamic analysis methods, an appendix contains a review of the mathematical methods most commonly used for such analysis.

Author: P. Fajfar
Publisher: Routledge
ISBN: 1351417207
Category : Technology & Engineering
Languages : en
Pages : 436

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Book Description
These proceedings, arising from an international workshop, present research results and ideas on issues of importance to seismic risk reduction and the development of future seismic codes.

Author: Hyerin Lee
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 184

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Author: Farzad Naeim
Publisher: Springer Science & Business Media
ISBN: 1461516935
Category : Technology & Engineering
Languages : en
Pages : 816

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Book Description
This handbook contains up-to-date existing structures, computer applications, and infonnation on planning, analysis, and design seismic design of wood structures. A new and very useful feature of this edition of earthquake-resistant building structures. Its intention is to provide engineers, architects, is the inclusion of a companion CD-ROM disc developers, and students of structural containing the complete digital version of the handbook itself and the following very engineering and architecture with authoritative, yet practical, design infonnation. It represents important publications: an attempt to bridge the persisting gap between l. UBC-IBC (1997-2000) Structural advances in the theories and concepts of Comparisons and Cross References, ICBO, earthquake-resistant design and their 2000. implementation in seismic design practice. 2. NEHRP Guidelines for the Seismic The distinguished panel of contributors is Rehabilitation of Buildings, FEMA-273, Federal Emergency Management Agency, composed of 22 experts from industry and universities, recognized for their knowledge and 1997. extensive practical experience in their fields. 3. NEHRP Commentary on the Guidelinesfor They have aimed to present clearly and the Seismic Rehabilitation of Buildings, FEMA-274, Federal Emergency concisely the basic principles and procedures pertinent to each subject and to illustrate with Management Agency, 1997. practical examples the application of these 4. NEHRP Recommended Provisions for principles and procedures in seismic design Seismic Regulations for New Buildings and practice. Where applicable, the provisions of Older Structures, Part 1 - Provisions, various seismic design standards such as mc FEMA-302, Federal Emergency 2000, UBC-97, FEMA-273/274 and ATC-40 Management Agency, 1997.

Author: M. J. N. Priestley
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 132

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Author: K. Maekawa
Publisher: CRC Press
ISBN: 1482288087
Category : Architecture
Languages : en
Pages : 768

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Book Description
This book describes the application of nonlinear static and dynamic analysis for the design, maintenance and seismic strengthening of reinforced concrete structures. The latest structural and RC constitutive modelling techniques are described in detail, with particular attention given to multi-dimensional cracking and damage assessment, and their p