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International Concrete Abstracts Portal

Showing 1-5 of 14 Abstracts search results

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


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: 

SP118-08

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


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: 

SP118-04

Date: 

January 1, 1990

Author(s):

J. C. Chern, C. H. Young, and K. C. Wu

Publication:

Symposium Papers

Volume:

118

Abstract:

Conventional concrete and mortar are both major construction materials because of their advantages in durability, economy, and comparably good mechanical properties. However, brittleness and low tensile strength are weak constitutions of these materials. Therefore, they provide less resistance to the propagation of cracks. Fibers can resist against the propagation of cracks due to the contribution of traction, resulting from the fibers-matrix bond mechanism, on the crack face. Some exact mathematical formulations to express thestress intensity factor and the crack opening displacement are proposed in this research to interpret the fracture behavior of fiber reinforced cementitious composites. Using these formulations, two fracture criteria can be performed to evaluate the tendency of crack propagation of this composite material. These two criteria are stress intensity factor and crack tip opening displacement. To achieve a more reasonable solution, the couple effect between the crack opening displacement and the fiber bridging traction is also considered. From the numerical results shown in this study, it is concluded that the fiber reinforced concrete provides higher resistance against the propagation of cracks than ordinary plain concrete, and one can clearly understand the resistance ability of fibers for the fracture behavior of concrete.

DOI:

10.14359/2928


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