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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 16 Abstracts search results
Document:
SP225-06
Date:
May 1, 2005
Author(s):
A. Scanlon
Publication:
Symposium Papers
Volume:
225
Abstract:
Current practice related to design of concrete structures for deflection control is reviewed. The paper discusses the limitations of the current code procedures based on minimum thickness rules and deflection calculations. Results are presented to demonstrate the sensitivity of deflections to span to depth ratio, sustained live load, and extent of cracking.
DOI:
10.14359/14378
SP225-13
March 1, 2005
A. Schokker, J. West, E. Villari, J. Breen, and M. Kreger
A number of different crack width prediction equations have been proposed for use with partially prestressed concrete structures, but laboratory and field results for members with varying levels of post-tensioning are limited. A durability study at The University of Texas at Austin involved beams with varying combinations of bonded post-tensioning and non-prestressed reinforcement. This work included extensive crack width measurements at varied load levels. A follow-up study is now on-going at Penn State University to consider beams with a combination of pretensioning and post-tensioning (such as found in spliced girder applications). This paper presents and discusses the measured crack data from these studies, and compares the data to selected existing crack width prediction models. Comparison of measured and predicted crack widths did not reveal a single comprehensive crack width prediction formula for the range of variables considered.
10.14359/14385
SP225-15
R. I. Gilbert
Cracking caused by both shrinkage and external loads in reinforced concrete members is examined both experimentally and analytically. The mechanisms of cracking and the factors affecting the time-varying width and spacing of flexural cracks in beams and slabs and direct tension cracks in longitudinally restrained members are examined. Laboratory tests on twelve reinforced concrete beams and slabs subjected to sustained service loads were conducted in order to measure and quantify the effects of steel area, steel stress, bar diameter, bar spacing, concrete cover, concrete strength and concrete shrinkage on the extent of flexural cracking and the width of flexural cracks both immediately after loading and in the long-term after almost 400 days under load. In addition, an analytical procedure is presented that models time-dependent cracking. Use is made of the tension chord model developed by Marti et al.1 which is here modified to study the tensile zone of a flexural member and the time-dependent effects of creep and shrinkage. A second series of tests on longitudinally restrained slab specimens is also reported and the analytical procedure is extended to model the time-dependent development of direct tension cracking.
10.14359/14387
SP225-09
K. B. Bondy, FACI
This paper critically examines the deflection criteria in Chapter 9 of the current ACI Building Code, ACI 318-02, with a particular focus on two-way non-prestressed slabs. The relationship between criteria based on deflection computations and arbitrary minimum thicknesses, which are independent of loading and concrete strength, are scrutinized. A numerical example is presented in which it is demonstrated that current code criteria can lead to unsatisfactory performance in heavily loaded slabs. Recommendations are made for changes to improve code deflection criteria.
10.14359/14381
SP225-03
S. E. Wallah, D. Hardjito, D. M. J. Sumajouw, and B. V. Rangan
As a relatively ‘new’ material, geopolymer concrete offers the benefits as a construction material for sustainable development. It utilises waste materials such as fly ash and has a very low rate of green house gas emission. This paper presents the study of the performance of fly ash based geopolymer concrete to sulfate attack. Test specimens were soaked in sodium sulfate solution and sulfuric acid solution for various periods of time, and the performance of geopolymer concrete is studied by evaluating the effect on the compressive strength, change in length and change in mass. Test results show that exposure to sodium sulfate has no significant effect on geopolymer concrete, whereas exposure to sulfuric acid affects the compressive strength.
10.14359/14375
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