ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

Showing 1-5 of 10 Abstracts search results

Document: 

SP236

Date: 

May 26, 2006

Author(s):

Editors: Adolfo Matamoros and Kenneth Elwood / Sponsored by: Joint ACI-ASCE Committee 445 and Joint ACI-ASCE Committee 441

Publication:

Symposium Papers

Volume:

236

Abstract:

Earthquakes worldwide have clearly demonstrated the vulnerability of reinforced concrete members to degradation in shear strength when subjected to cyclic loading. Such degradation can lead to significant damage to the structure and, possibly, even collapse. With the advancement of performance-based earthquake engineering, where the response of the structure must be traced through all levels of damage, there is a significant need to accurately define the deformation capacity and shear strength for such members. This symposium publication represents an effort from researchers across the globe trying to address this challenging problem. Although at the time of publication there are some methodologies that can be used in performance-based earthquake engineering, there is a significant need for improved methods better suited for these types of applications. Furthermore, one of the concerns often expressed by researchers is that test data used in the past to develop and calibrate existing models consisted of relatively small data sets. This problem is compounded by differences between experimental studies in aspects such as the type of load history used, the manner in which deformations were recorded during tests, and the definition of displacement and strength at failure. The recent development of the PEER column database, hosted by the University of Washington, provided a valuable resource to overcome some of these problems. It presented researchers with a larger pool of data, which included the full hysteretic response of every column in the data set. Although this represented a very significant step forward, efforts of this kind should continue to improve the ability of researchers to calibrate and evaluate models for shear strength and deformation capacity. A joint technical session was organized by Joint ACI-ASCE Committees 441, Reinforced Concrete Columns, and 445, Shear and Torsion, during the American Concrete Institute’s Fall 2004 Convention in San Francisco, CA. The goal of the technical session was to showcase recent developments in this area, with the hope that continued discussion will lead to improved models that are suitable for performance-based engineering. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP236

DOI:

10.14359/16443


Document: 

SP236-08

Date: 

May 1, 2006

Author(s):

P. Adebar

Publication:

Symposium Papers

Volume:

236

Abstract:

The new provisions in the 2004 Canadian code for flexural displacement capacity of concrete walls, and the new provisions for seismic shear design of slender concrete walls are presented. To facilitate explanation of the seismic shear provisions, general expressions for shear design are first presented, and the non-seismic shear design provisions in the Canadian and ACI 318 building codes are briefly reviewed. According to the new seismic shear design provisions presented here, the maximum shear force and concrete contribution depend on the inelastic rotation demand in the plastic hinge, and the compression stress (critical crack) angle used to determine the quantity of horizontal reinforcement depends on the axial compression stress applied on the wall. The 2004 Canadian code provisions generally require more horizontal reinforcement than the ACI 318 provisions except when inelastic rotational demand is small and axial compression stress is large; however, the Canadian provisions permit significantly higher shear stress for high-strength concrete walls. The new provisions can be used to design concrete walls given the expected level of drift demand or, as demonstrated in this paper, can be used to estimate drift capacity of walls accounting for the significant influence of shear.

DOI:

10.14359/18217


Document: 

SP236-01

Date: 

May 1, 2006

Author(s):

D.V. Syntzirma and S.J. Pantazopoulou

Publication:

Symposium Papers

Volume:

236

Abstract:

The sequence of failure in reinforced concrete (RC) prismatic members is used as a tool in estimating dependable deformation capacity. Response mechanisms that may limit the response leading to damage localization are identified (web diagonal cracking, bar buckling, disintegration of compressive struts due to load reversal, and anchorage failure of primary reinforcement). Deformation components are additive only if stable hysteretic response controlled by flexure prevails. In all other cases, the deformation component associated with the controlling mode of failure dominates the overall deformability of the member. Because the sequence of failure depends to a large extent on load history, deformation attained at any particular level of load is also load history dependent. This is why experimental values for deformation capacity reported in international literature are characterized by excessive scatter. The proposed methodology is applied to a number of published column tests. Analytical estimates are evaluated through comparisons with experimental results and by parameter studies conducted in order to examine the sensitivity of the estimated displacement limit at compression bar buckling to important design variables.

DOI:

10.14359/18204


Document: 

SP236-04

Date: 

May 1, 2006

Author(s):

S. Bae and O. Bayrak

Publication:

Symposium Papers

Volume:

236

Abstract:

The research reported herein is aimed at identifying the relationship between curvature ductility, displacement ductility and drift capacity of reinforced concrete columns. In order to achieve this goal and to study the effects of aspect ratio (L/h) on the seismic performance of columns, an analytical procedure that can be used to evaluate the deformation capacity of reinforced concrete columns is developed. Experimentally verified constitutive models for reinforcing bar slip, inelastic buckling of bars, and confinement of concrete are used. The P-? effect is also taken into account. Model verification is performed by predicting the behavior of columns tested by different researchers. The effect of longitudinal reinforcement ratio, volumetric ratio of confining reinforcement, column aspect ratio, and axial load level on the relationship between various ductility parameters is evaluated and discussed.

DOI:

10.14359/18209


Document: 

SP236-03

Date: 

May 1, 2006

Author(s):

S. Pujol and M.A. Sozen

Publication:

Symposium Papers

Volume:

236

Abstract:

The effect of shear reversals on the drift capacity of reinforced concrete columns is studied comparing computed limiting drift for monotonically increasing load and limiting drift for cyclic loads. The latter is estimated using models calibrated with data from tests of columns subjected to shear reversals. The comparison indicates that, within the ranges considered, shear reversals cause stiffness decay at displacements that can be as low as one quarter of the displacement capacity for monotonically increasing shear. The effects of stiffness decay on the demand for a single degree of freedom system subjected to strong ground motion are studied. The formulations considered indicate that, if relative reduction in lateral stiffness is associated with an equal relative reduction in damping, shear reversals affect drastically the resistance of the system but not dynamic demand. Ranges are given defining a domain within which the effects of shear reversals may be ignored.

DOI:

10.14359/18207


12

Results Per Page 




Please enter this 5 digit unlock code on the web page.