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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:
SP117-09
Date:
October 1, 1989
Author(s):
M. K. Tadros,A. Yousef, and Y. S Joo
Publication:
Symposium Papers
Volume:
117
Abstract:
Deals primarily with statically indeterminate beams where settlement of the supports can produce stresses. A method of estimating the effects of support settlement is presented. The method accounts for the fact that soil consolidation and the corresponding support settlement often develop over an extended period of time. The method also demonstrates that creep of concrete can reduce the ultimate settlement-induced stresses in uncracked members by as much as 60 percent of the elastic values. Furthermore, flexural cracking of concrete results in reduction of the member stiffness. This corresponds to further relief of the settlement-induced stresses. Field studies on the effects of settlement in several bridges are presented. The relationship between the amount of settlement and its structural effects is illustrated.
DOI:
10.14359/2824
SP117-10
U. Ersoy and T. Tankut
Two case studies are presented as examples illustrating the problem of shrinkage in reinforced concrete buildings in Central Turkey, where humidity is quite low and extreme temperature changes take place. The first case discussed is a structure consisting of one-bay frames with curved beams spanning 36 m. Axial tension created by shrinkage had reduced the axial thrust in the beams causing a considerable drop in the flexural capacity and leading to severe cracking. The second case presented is a grain bin where vertical cracks in the silo walls were explained mainly by the restraining effect of the rigid foundation against shrinkage deformations. Types and causes of shrinkage cracks are discussed, and the methods of analysis used are briefly explained for each case. The estimated values of shrinkage deformations in dry climates with extreme temperature changes are compared with experimental values, and some serious possible consequences are explained.
10.14359/2830
SP117-12
M. R. Resheidat
Internal algorithms for creep and shrinkage when substituted by approximate algebraic equations lead to the adoption of a computational procedure substantially independent of linear equations adopted in the time-dependent prediction model. Presented herein are the numerical results of stresses and strains of reinforced and post-tensioned concrete bridge box-sections where creep and shrinkage are considered. Field measurements of deformations have been recorded and compared with the corresponding numerical results obtained by utilizing a computer program. Results are presented in a graphical form. It may be concluded that the computer method is a convenient tool for describing the behavior of structural concrete sections considering creep and shrinkage in connection with performance and service ability.
10.14359/2837
SP117-13
C. J. Hookham and T. L. Bailey
Long-term durability of reinforced and prestressed concrete structures in U.S. nuclear power plants was identified as a critical issue in the feasibility studies of plant life extension. Evaluation of concrete structures at several operating plants included studies of known concrete degradation modes, performance of condition surveys/testing, and service life prediction. Results indicate that service lives of 60 or more years are achievable, provided that preservation activities are conducted for these concrete structures.
10.14359/2843
SP117-02
K. Van Breugel an C. Van Der Veen
An analytical procedure is described for predicting the development of vertical cracks in thin-walled and thick-walled cylindrical structures subjected to membrane forces and thermal loads. Sustained, axisymmetrical (thermal) loads and thermal cyclic loading may jeopardize, due to cracking, the serviceability (in this case the tightness) of thin-walled cylinders. Mathematically obtained crack patterns have been compared with field observations: a good agreement between theory and practice could be established from this comparison. On the basis of a reliable prediction of crack patterns, cost-benefit analyses are feasible to weigh crack control measures against possible repair costs in case these measures were neglected. An example of such an analysis shows an initial increase of reinforcement in view of crack control to be preferable to repair (grouting) of cracks.
10.14359/2809
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