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International Concrete Abstracts Portal

Showing 1-5 of 14 Abstracts search results

Document: 

SP118-13

Date: 

January 1, 1990

Author(s):

Arne Hillerborg

Publication:

Symposium Papers

Volume:

118

Abstract:

The stress-deformation relation now generally accepted for tensile fracture, i.e., with the descending branch described by means of a stress-displacement relation in a localized band, has been applied to the compressive stresses in a bent, reinforced beam. The displacement in this band is averaged over a length, which is proportional to the depth of the compression zone. The resulting average stress-strain relation, which is strongly size-dependent, is used for the analyses of the stresses in a rectangular beam section, and for the corresponding moment-curvature relationship. The results differ appreciably from those from conventional assumptions. The new approach shows a better agreement with test results than the conventional approach. Further test comparisons are, however, recommended. The new approach may form the basis of changed design assumptions, particularly for high-strength concrete.

DOI:

10.14359/2983


Document: 

SP118-12

Date: 

January 1, 1990

Author(s):

T. Shioya, M. Iguro, Y. Nojiri, H. Akiyama, and T. Okada

Publication:

Symposium Papers

Volume:

118

Abstract:

Experimental and theoretical studies on shear strength of large reinforced concrete beams are presented. The shear strength of a reinforced concrete beam without shear reinforcement gradually decreases as an effective depth d of a beam increases, and is generally called the size effect. From the result of the experiment on large beams, the size effect of a beam exists even for a beam deeper than 100 cm which had been outside of the scope of past experiments, and the size effect at d ò 100 cm may be considered to be inversely proportional to the fourth root of the effective depth. According to the result of a nonlinear finite element analysis, the size effect on flexural tensile strength of concrete and shear transfer across crack surfaces must be considered in estimating the shear strength of a large reinforced concrete beam.

DOI:

10.14359/2978


Document: 

SP118-11

Date: 

January 1, 1990

Author(s):

Y. S. Jenq and S. P. Shah

Publication:

Symposium Papers

Volume:

118

Abstract:

The shear resistance of reinforced concrete beams without shear stirrups has been shown to be dependent on the size of beams. It was reported that as the beam depth increases, the shear resistance of the reinforced concrete beams decreases. Furthermore, the final failure mode of the reinforced concrete beams were found to be dependent on the strength as well as beam size. All other factors (i.e., maximum aggregate size, steel ratio, and proportion of specimen dimensions) being equal, large beams and early age beams (which have relatively low strength) were observed to fail in diagonal shear while small beams and matured beams failed in flexure. To explain the size effect on the shear resistance and final failure mode of reinforced concrete beams, a fracture mechanics approach was used in the present study. It was concluded that the effect of size on the final failure mode and shear resistance of reinforced concrete beams can be reasonably explained using the fracture mechanics concept.

DOI:

10.14359/2973


Document: 

SP118-10

Date: 

January 1, 1990

Author(s):

A. Carpinteri

Publication:

Symposium Papers

Volume:

118

Abstract:

Progressive cracking in structural elements of concrete is considered. Two simple models are applied, which, even though different, lead to similar predictions for the fracture behavior. Both virtual crack propagation model and cohesive limit analysis show a trend toward brittle behavior and catastrophical events for large structural sizes. Such a trend is fully confirmed by more refined finite element investigations and by experimental testing on plain and reinforced concrete members.

DOI:

10.14359/2968


Document: 

SP118-09

Date: 

January 1, 1990

Author(s):

Jin-Ken Kim, Seok-Hong Eo, and Hong-Kee Park

Publication:

Symposium Papers

Volume:

118

Abstract:

In most of the structural members with initial cracks, the strength tends to decrease as the member size increases. This phenomenon is known as size effect. Among the structural materials of glass, metal, or concrete, etc., concrete represents the size effect even without initial crack. According to the previous size effect law, the concrete member of very large size can resist little stress. Actually, however, even the large-size member can resist some stress if there is no initial crack. In this study, the empirical models for uniaxial compressive strength that are derived based on nonlinear fracture mechanics are proposed by the regression analysis with the existing test data of large-size specimens.

DOI:

10.14359/2962


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