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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: 

SP118-06

Date: 

January 1, 1990

Author(s):

L. Nobile

Publication:

Symposium Papers

Volume:

118

Abstract:

Focuses on the formulation of a self-consistent model for a compressed concrete containing randomly distributed flat microcracks. A general formulation of the constitutive law for such material is obtained, finding the overall mechanical response to be strongly nonlinear in the region near the maximum in the stress-strain curve.

DOI:

10.14359/2942


Document: 

SP118-07

Date: 

January 1, 1990

Author(s):

Arne Hillerborg

Publication:

Symposium Papers

Volume:

118

Abstract:

A fracture mechanics approach is presented. In this approach, the complete material behavior during tensile fracture is described in a way suitable for the analysis of failure of structures. Two examples are given of practical applications, in which the results can be compared with code specifications. The first is the cracking strength of a beam. It is demonstrated that the formal flexural stress that causes cracking decreases as the depth of the beam increases. The second example is the shear strength of a beam without shear reinforcement. The theoretical results show a good agreement with test results. There seem to be reasons to revise the rules in the ACI Building Code regarding the influence of beam depth, of span-to-depth ratio, and of the amount of longitudinal reinforcement on the shear strength. The tensile toughness of concrete, expressed as fracture energy, proves to be an important material property, which ought to be taken into account.

DOI:

10.14359/2947


Document: 

SP118-01

Date: 

January 1, 1990

Author(s):

Victor c. Li

Publication:

Symposium Papers

Volume:

118

Abstract:

Reviews the tensile failure of concrete structures subjected to a variety of practical loading. Attention is focused on the propensity of fracture failure of concrete structures and the fracture properties of cementitious materials. The relevance of fracture mechanics to modern concrete design code is highlighted.

DOI:

10.14359/2908


Document: 

SP118-08

Date: 

January 1, 1990

Author(s):

Zdenek P. Bazant, Siddik Sener, and Pere C. Prat

Publication:

Symposium Papers

Volume:

118

Abstract:

This symposium contribution gives a preliminary report on tests of the size effect in torsional failure of plain and longitudinally reinforced beams of reduced scale, made of microconcrete. The results confirm that there is a significant size effect, such that the nominal stress at failure decreases as the beam size increases. This is found for both plain and longitudinally reinforced beams. The results are consistent with the recently proposed Bazants size effect law. However, the scatter of the results and the scope and range limitations prevent it from concluding that the applicability of this law has been proven in general.

DOI:

10.14359/2955


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