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  • 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.

International Concrete Abstracts Portal

Showing 1-5 of 14 Abstracts search results

Document: 

SP117-01

Date: 

October 1, 1989

Author(s):

T. I. Campbell, J. C. Jofriet, and W. M. Slater

Publication:

Symposium Papers

Volume:

117

Abstract:

A study of concrete water tanks in the Province of Ontario indicated an unusually high rate of deterioration. The different types of tanks in existence are described, and observed defects and possible related mechanisms are discussed. Particular attention is directed to freeze-thaw cycles and internal ice formations, and methods for estimation of these effects are proposed. Criteria and recommendations for the design of reinforced concrete storage structures in both freezing and nonfreezing environments are discussed.

DOI:

10.14359/3334


Document: 

SP117-10

Date: 

October 1, 1989

Author(s):

U. Ersoy and T. Tankut

Publication:

Symposium Papers

Volume:

117

Abstract:

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.

DOI:

10.14359/2830


Document: 

SP117-06

Date: 

October 1, 1989

Author(s):

R. M. Samra and W. L. Gamble

Publication:

Symposium Papers

Volume:

117

Abstract:

A rational method of analysis is developed that can be used on a computer to determine the behavior of reinforced concrete columns under sustained service loads. At specific time intervals, trial-and-error procedures are used to establish strain compatibility and equilibrium conditions at each of several cross sections of a member. Curvatures are integrated to find the deflected shape, and an iterative approach is used to find the stable deflected shape if there are secondary moments. The analysis calculates the effect of creep on the stress redistribution between concrete and steel and on the deflections of members subjected to variable axial loads and variable moments. The effects of shrinkage and cracking are also included. The applicability of the analysis is partially verified by comparison with laboratory and field investigations reported by various researchers. In most cases, a good correlation is obtained between the analytical results and the measured results.

DOI:

10.14359/2817


Document: 

SP117-04

Date: 

October 1, 1989

Author(s):

M. M. Elnimeiri and M. R. Joglekar

Publication:

Symposium Papers

Volume:

117

Abstract:

Differential elastic, creep, shrinkage, and thermal deformations of vertical concrete elements, columns, and walls in tall building structures require special attention to insure proper behavior for both strength and serviceability of the structure and the attached nonstructural elements. The long-term serviceability problems include out-of-level floors in both concrete and composite buildings, and cracking and deformations of internal partitions and external cladding elements. A procedure is developed to predict the long-term deformations of reinforced concrete columns, walls, and composite columns. The procedure incorporates the effects of concrete properties, construction sequence, and loading history. For composite columns, the effects of load transfer from the steel erection column to the reinforced concrete column are also included. Methods to minimize differential shortening of columns and walls are discussed. The methods involve corrections during both design and construction phases. Differential shortening effects for three tall buildings, in Chicago, which were designed using the procedure, are discussed. Results from six years of field measurements of column shortening are compared with predicted values.

DOI:

10.14359/3318


Document: 

SP117-13

Date: 

October 1, 1989

Author(s):

C. J. Hookham and T. L. Bailey

Publication:

Symposium Papers

Volume:

117

Abstract:

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.

DOI:

10.14359/2843


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