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International Concrete Abstracts Portal

Showing 1-5 of 29 Abstracts search results

Document: 

SP238-18

Date: 

October 1, 2006

Author(s):

H. Nakahara and K. Sakino

Publication:

Symposium Papers

Volume:

238

Abstract:

In order to evaluate the load carrying capacity and ductility of hinging zone ofthe concrete filled steel tubular (CFT) columns, tests are carried out on 12 circular speci-mens and 18 square specimens subjected to uniform bending under a constant axial load.The experimental parameters are: 1) depth to thickness ratio (D/t ratio) and width to thick-ness ratio (B/t ratio) of steel tube; 2) axial load ratio; 3) material strength; 4) deformationhistory and 5) annealing. One of the features of the test is the wide range of D/t and B/tratio. The range of D/t ratio of the circular CFT columns are 40.5-160 and the range of B/t ratio of the square CFT columns are 32.8-98.0, respectively. The experimental load-de-formation relations are compared with those of the elasto-plastic analysis based on theproposed stress-strain relationships established for the filled concrete and for the steel tube.The analytical results show good agreement with the test results for all specimens. Thisimplies that the proposed stress-strain relationships for CFT columns are useful to predictthe characteristics of the filled concrete and the steel tube.

DOI:

10.14359/18278


Document: 

SP238-15

Date: 

October 1, 2006

Author(s):

T.-H. Tan and X. Sun

Publication:

Symposium Papers

Volume:

238

Abstract:

This paper presents an experimental investigation to determine the ultimate strength of concrete under triaxial compression. Concrete of 4 different strength levels were employed and triaxal tests were performed on 100 x 300 mm cylindrical specimens to establish the failure criteria for low, normal and high-strength concrete. The effects of confining pressure and stress path on different grades of concrete were also studied and test results were used to verify the failure criteria proposed by other researchers.

DOI:

10.14359/18275


Document: 

SP238-17

Date: 

October 1, 2006

Author(s):

K. Sakino

Publication:

Symposium Papers

Volume:

238

Abstract:

It has been widely known that concrete filled steel tubular (CFT) columns have much higher strength and deformation capacities than common reinforced concrete (RC) columns because of beneficent interactive confinement effect between the filled concrete and the steel tube. The confinement effect by steel tube furthermore contributes to improving ductility of high-strength concrete, and enables application of the CFT columns in high-rise buildings located on seismic regions. This paper describes the axial and the flexural behaviors of CFT columns with circular and square sections based on many experimental researches conducted in Japan. The emphasis of this paper will be placed on the stress-strain curve models for concrete in CFT columns, which play the fundamental role in assessing both of the axial and the flexural behaviors of the CFT columns.

DOI:

10.14359/18277


Document: 

SP238-03

Date: 

October 1, 2006

Author(s):

S. Bae and O. Bayrak

Publication:

Symposium Papers

Volume:

238

Abstract:

In performance-based seismic design, evaluation of the deformation capacity of reinforced concrete columns is of paramount importance. The deformation capacity of a column can be expressed in several different ways: (1) curvature ductility, (2) displacement ductility, or (3) drift. Even though several performance-based confining reinforcement design procedures have been proposed, the relationship between different ductility factors is not clearly understood. The effect of concrete strength, longitudinal reinforcement ratio, volumetric ratio of confining reinforcement, shear span-to-depth ratio, and axial load level on the relationship between different ductility factors was studied. Finally, the confinement reinforcement design requirements of current design codes and recently proposed performance-based design methods were compared and critically examined.

DOI:

10.14359/18263


Document: 

SP238-02

Date: 

October 1, 2006

Author(s):

J.P. Moehle and D.E. Lehman

Publication:

Symposium Papers

Volume:

238

Abstract:

A current focus in earthquake engineering research and practice is the development of seismic design procedures whose aim is to achieve a specified performance. To implement such procedures, engineers require methods to define damage in terms of engineering criteria. Previous experimental research on bridge columns has focused on component failure, with relatively little attention to other damage states. A research program was undertaken to assess the seismic performance of well-confined, circular-cross-section, reinforced concrete bridge columns at a range of damage states. The test variables included aspect ratio, longitudinal reinforcement ratio, spiral reinforcement ratio, axial load ratio, and the length of the well-confined region adjacent to the zone where plastic hinging is anticipated. The experimental results are used to identify important damage states and to link those states to engineering parameters.

DOI:

10.14359/18262


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