In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Become an ACI Member
Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
ACI World Headquarters
38800 Country Club Dr.
Farmington Hills, MI
ACI Middle East Regional Office
Second Floor, Office #207
The Offices 2 Building, One Central
Dubai World Trade Center Complex
Phone: +971.4.516.3208 & 3209
ACI Resource CenterSouthern California
Feedback via Email
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 10 Abstracts search results
September 1, 1992
Radomir Pukl, Rolf Eligehausen, and Vladimir Cervenka
Computer analyses of the pullout tests of anchors embedded in concrete were performed for the Round Robin Analysis of the RILEM Committee on Fracture Mechanics of Concrete. The test specimens were concrete plates with steel anchors in the plane stress state. The geometry of the specimen was varied in order to study the size effect and the shape effect. The investigation was performed by means of the computer simulation of the tests. Only limited comparison with the real laboratory experiments was used to verify the results. The computer simulation was made by means of the program SBETA, which was developed by the authors and is based on the smeared crack approach and the nonlinear elasticity. Two crack models were used to analyze each specimen: the rotated crack model and the fixed crack model. In total, 36 computer simulations were made. Each simulation provided the load-displacement diagram of the anchor and a sequence of crack patterns, deformed states, and stress states. A size effect law in the exponential form was derived from the computer experiments.
S. L. McCabe, D. Darwin, O. C. Choi, and H. Hadje-Ghaffari
The recent introduction of epoxy coating to reinforcing steel has made the study of bond, and the effect of this coating, all the more important. A recent large scale study of bond performance of epoxy-coated and uncoated reinforcement conducted at the University of Kansas using modified cantilever beam-end specimens has shown the effects of various parameters on bond. These specimens placed the bar and surrounding concrete in tension, simulating the situation in actual members. A prescribed bond test region, the bonded length, was placed at a discrete distance, the lead length, from the front of the specimen to prevent surface effects from interfering with the test region. The experimental work has provided ample evidence of the fundamental fracture mechanics aspects of bond failure and the subsequent specimen failure. Splitting failure of the beam-end specimens was observed consistently in all tests where a fracture plane formed above the bond test region and propagated quickly through the tension region of the specimen. Tests indicated that the bonded length of the bar, the value of the lead length, and the amount of cover were all important parameters. The paper presents the results of an analytical evaluation of the bond process and specimen fracture that was observed in the laboratory, using nonlinear finite element analysis to study the effects of interface properties on the fracture behavior and failure load. The majority of the beam-end specimen was modeled using linear elastic elements representing one-half of the symmetric experimental specimen. The actual bar-concrete interface was modeled using link elements and a Mohr-Coulomb failure model. Rod elements joined the specimen to the specified crack plane located at the center line of the specimen. The fracture process was modeled using Hillerborg's fictitious crack model. The behavior observed in the laboratory for coated and uncoated bars has been accurately predicted using this procedure. The fracture process and resulting overall bond performance has been studied analytically to assess the effects of interface properties on the fracture behavior. The analytical studies confirmed that coating reduced the relative bond strength with respect to that of an uncoated bar, while the absolute bond strength was found to increase with additional cover and lead length.
Zdenek P. Bazant
Reviews recent theoretical and experimental results on the size effect in brittle failures of reinforced concrete structures caused by the release of stored energy After summarizing the size effect law and explaining the novel concept of a brittleness number, the results of recent tests of diagonal shear failure, punching shear failure, torsional failure, and pullout failure are discussed. These results, which were obtained on geometrically similar specimens with a broad range of sizes, are found to be in excellent agreement with the theoretical size effect law. The experimental evidence is much stronger than that which was previously obtained by analyzing a large amount of test results from the literature, which were not obtained on geometrically similar specimens and were limited to a narrow size range. It is also pointed out that the test data on diagonal shear disagree with the classical Weibull-type theory of size effect, thus strengthening the theoretical argument against using this theory for the size effect in concrete structures whose maximum load is much larger than the cracking initiation load. The test results indicate that the presently considered fracture mechanics size effect ought to be incorporated into the formulas for the contribution of concrete to the ultimate load capacity in brittle failures of concrete structures. It is shown that such formulas can be based on the brittleness number. For any given structure shape, this number can be determined from size effect tests. However, prediction of this number without such test data will require some further research.
W. M. Ashmawi, M. H. Baluch, and a. K. Azad
Proposes a fracture mechanics approach to crack control design of reinforced concrete beams in flexure (Mode I). The model yields the minimum area of tension steel required of a concrete beam of rectangular cross section to safely sustain a design moment within the prescribed limit of permissible crack height. An iterative procedure is developed by satisfying simultaneously the fracture criterion of crack growth and the equilibrium condition at incipient fracture.
Christian La Borderie, Jacky Mazars, and Gilles Pijaudier-Cabot
Progressive microcracking and crack closure effects are the most important phenomena which need to be described in finite element calculations of reinforced concrete structures subjected to cyclic or seismic loads. Microcracking produces a loss of stiffness which is usually modeled with continuous damage mechanics. Crack closure effects such as inelastic deformations and stiffness recovery remain features that must be incorporated in the constitutive relations describing the response of concrete under cyclic loadings. These effects are introduced into a novel damage model in a rigorous, consistent fashion. An attempt to derive the constitutive relations for fiber reinforced concrete using this model is also described. The implementation of these constitutive relations into a layered beam finite element code is discussed, and computations on medium-size bending beams and a beam-column joint subjected to cyclic loading are compared with experiments. Although the computational method remains simple and sufficiently fast for engineering applications, the good agreement obtained with test data shows that the constitutive relations capture very well the main characteristics of the behavior of concrete.
Results Per Page
Please enter this 5 digit unlock code on the web page.