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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 8 Abstracts search results
Document:
SP113-07
Date:
April 1, 1989
Author(s):
B. O. Aalami and F. G. Barth
Publication:
Symposium Papers
Volume:
113
Abstract:
Based on extensive observations and a survey of the performance of unbonded post-tensioned buildings, paper presents a categorization of the common cracks in beams and slabs, and the principal causes of crack formation due to restraining effects of supporting structures are discussed in detail. Current methods of crack formation control are also presented and evaluated, and the consequences of cracks on serviceability and strength of post-tensioned buildings are reviewed. In addition, recommendations are made for crack mitigation and maintenance of buildings that are post-tensioned with unbonded tendons.
DOI:
10.14359/3006
SP113-03
M. N. Hassoun and K. Sahebjam
Aim is the study of the cracking of partially prestressed concrete beams under increasing load up to failure. Different combinations of prestressed and nonprestressed steel were used. The strength of the nonprestressed steel varied between 40 and 250 ksi. Spacings and crack widths were measured and reported. An expression is introduced to calculate the maximum crack width of partially prestressed concrete flexural members.
10.14359/2999
SP113-06
P. R. Chadrabarti
An attempt is made to study the crack formation, crack propagation, and the postcracking behavior until failure of four-panel prestressed concrete flat plates having two-way continuous parabolically draped unbonded post-tensioning tendons. The test specimens closely simulate the corner panels of an actual flat plate floor system having simple supports along the edges. The simple support system is similar to that provided by ledger beams or walls. The effect of added mild steel on the crack initiation, crack propagation, crack width control, and postcracking behavior is also studied. Recommendations are also made for further research.
10.14359/3003
SP113-01
E. G. Nawy
More prestressed beams incorporating mild steel reinforcement are built today with allowance of tension in the concrete, that is, partial prestressing. Consequently, a study of their cracking behavior and control of the crack width and distribution are significant. Available experimental data on the cracking behavior of prestressed beams is limited. Because of the importance of serviceability behavior of these elements, several experimental and analytical investigations have been undertaken and expressions proposed. Simple mathematical expressions have been developed. The proposed expressions for evaluating crack widths in partially prestressed beams at working load and overload have been developed in terms of the controlling parameters, namely, the variation in the steel reinforcement and percentage of the prestressing tendons and the nonprestressed reinforcement. The mathematical model is applied to tests on 20 simply supported pretensioned 9 ft span beams, 4 two-span continuous beams of effective 9 ft span, and 22 simply supported post-tensioned beams of 7 ft, 6 in. span. The major controlling parameters were the variation in the steel reinforcement percentage of the prestressed tendons and the nonprestressed reinforcement. The effect of concrete cover was incorporated in the value of the concrete area in tension.
10.14359/2996
SP113-02
M. H. Harajli and A. E. Naaman
Study was conducted to evaluate cracking in partially prestressed concrete beams under both static and cyclic fatigue loading. It comprises two parts: an experimental investigation and an analytical modeling of crack width increase under cyclic fatigue loading. In the experimental part, 12 different sets of beams were tested in four-point bending. Each set comprised two identical beams. One beam was tested to failure under monotonically increasing load, while the second beam was tested in fatigue at a constant load range simulating full live load. In the analytical part of the study, a model for computing the increase in crack width under cyclic fatigue loading is developed. The model accounts for the effect of change in steel stress due to cyclic creep of concrete in compression, the increase in slip due to bond redistribution, concrete shrinkage, and cyclic creep of concrete in tension. Results predicted by the model were found to be in good agreement with the experimental results observed in this study, as well as results reported elsewhere.
10.14359/2998
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