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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:
SP117-13
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
SP117-04
M. M. Elnimeiri and M. R. Joglekar
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.
10.14359/3318
SP117-05
P. Arumugasaamy and R. N Swamy
Long-term behavior of in situ reinforced concrete columns in two structures during construction, occupancy, and service is reported. Extensive strain and moisture movements were made up to about 10 years of service, and long-term movements at 25 to 30 years were then estimated. The stress history experienced by the columns in the second structure was monitored through a stress meter embedded in one of the columns, and the influence of reinforcement and the time-dependent movements on the stress history is described. The gradual but significant stress redistribution with time and the resulting concrete-steel load transfer is also discussed. Results show that the time-dependent deformation in in situ columns occurred over a very long period of time and continue to occur at a very small rate. However, the majority of movements in the columns occurred during the first 5-year period after construction of the columns. It is shown that dead load appears to be the predominant load carried by the columns. The design steel stress has been exceeded in several columns within 10 years of service life; however, none of the steel is expected to yield in 50 years of service life. Based on the in situ performance of columns along with other available data, a design recommendation is made to incorporate the effects of load transfer from concrete to steel at the design stage.
10.14359/3324
SP117
Editor: Anis Farah
SP-117 If you are a structural engineer or a contractor, this important new volume will enhance your understanding of the most up-to-date data and techniques for assessing the long-term serviceability of new and existing concrete structures.
10.14359/14150
SP117-11
P. Arumugasaamy and R. N. Swamy
Presents a simple design aid for predicting long-term (up to 50 years) movements in reinforced concrete columns and bridge beams made of normal and lightweight aggregate concrete. The method is based on the principle of superposition using a creep factor chart, which takes into account varying sizes of members, age at loading, exposure conditions, and the percentage of reinforcement, and it requires only a knowledge of the concrete strength and the loading history of the member. The method is developed from the study of in situ movements in two reinforced concrete structures subjected to increment loading. The shrinkage strains in columns are predicted using a shrinkage chart, which requires only a knowledge of elastic modulus of concrete at 28 days. The predicted load-induced and basic strains show excellent agreement with measured strains in the two structures, and the method shows good agreement with literature. The paper demonstrates how the simple method of predicting long-term movements in buildings and bridges can be utilized by the structural engineer as a designer's tool.
10.14359/3165
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