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Home > Publications > 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.
Showing 1-5 of 14 Abstracts search results
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
SP118-09
Jin-Ken Kim, Seok-Hong Eo, and Hong-Kee Park
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.
10.14359/2962
SP118-10
A. Carpinteri
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.
10.14359/2968
SP118-05
Sawarng Ratanalert Ratanalert and MethiI Wecharatana
Many fracture mechanics models have been proposed in recent years to account for the nonlinear behavior of concrete around the crack tip region. These well-known models are the fictitious crack model (FCM) by Hillerborg, the crack band model (CBM) by Bazant, and the two-parameter fracture model (TPFM) by Jenq and Shah, etc. To model the fracture process zone or microcracked zone, these models often assumed the linear or bilinear stress-displacement relationship to simplify the analysis since actual relationships were not available due to difficulties in conducting direct tension tests. To avoid tedious numerical computation and the need of stress-displacement relationship, TPFM was proposed based on the simple LEFM concept. The model was quite accurate when applied to the notched beam test. All these models presented some degree of satisfaction when comparing with some experimental data. Since more direct tension tests with complete postpeak stress-displacement relationships have been successfully conducted in recent years, the need of assuming the stress-displacement relationship or using the indirect notched beam test is no longer necessary. An evaluation of the FCM using the observed stress-displacement relationships versus the assumed one seems to be an interesting task to verify the validity of the model. For TPFM, the proposed two unique fracture parameters should be verified for specimen size independence. A series of experiments were conducted on two types of test specimens (notched beam and compact tension) with different geometries. The results indicate that the parameters recommended in TPFM seem to be unique only for the notched beam specimen. The same two parameters were found to be tenfold larger for the compact tension specimen. For FCM, the predicted load-CMOD and load-deflection curves using the observed stress-displacement relationship are in better agreement with experimental data than those determined from the assumed linear relationship. Although theoretically both predicted load-CMOD and load-deflection curves should have the same order of accuracy, in this study, they were found to be substantially different.
10.14359/2934
SP118-08
Zdenek P. Bazant, Siddik Sener, and Pere C. Prat
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.
10.14359/2955
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