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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 20 Abstracts search results
Document:
SP76
Date:
October 1, 1982
Author(s):
Aberdeen Publication
Publication:
Symposium Papers
Volume:
76
Abstract:
SP76 A collection of 19 papers on creep and shrinkage in concrete structures. The papers discuss the effects of creep and shrinkage from the practical standpoint of the designer and offer recent research. Topics include: effects of volume changes, time-dependent slab deflections, predicting long-term prestress losses, creep strains and stress redistribution in reinforced concrete columns, analyzing time-dependent forces in continuous concrete structures, stress redistribution in cable-stayed concrete structures, drying shrinkage of high-strength concrete with superplasticizer, deflection of prestressed concrete beams. The book also includes a report from the ACI Committee on Creep and Shrinkage (209R-82) which reviews the methods for predicting creep, shrinkage and temperature effects in concrete structures. Simplified methods are used to predict the material response and to analyze the structural response under service conditions.
DOI:
10.14359/14128
SP76-04
Andrew Scanlon
The results of a parameter study of factors affecting time-dependent slab deflections are presented. The study is based on a finite element plate-bending analysis. Concrete is treated as an ageing linear viscoelastic material and the effects of shrinkage and cracking are included. Factors studied include creep and shrinkage, tensile behaviour of concrete, span to depth ratio, column width to span ratio, loading history, and reinforcement layout. A brief assessment is made of simplified procedures for computing slab deflections.
10.14359/6785
SP76-05
Heinrich Trost
The proposed calculation procedure is based on a reference deflection at the interesting point of the uncracked concrete member. This reference deflection is calculated on the basis of the existing distribution of the gross section stiffness-in analogy to the usual determination of the design forces in statically indeterminate systems-- as available from tables or handbooks. Then this reference value, either for the maximum service load or for the sustained load when time-dependent effects are concerned, is multiplied by reinforcement-dependent coefficients given in figures or calculable from closed formulae in order to obtain the initial deflection and the time-dependent deflection due to creep and shrinkage. The probable deflection, as the prognostic value of interest and in which the deflection-reducing effect of the reinforcement and the tension stiffening is considered, is determined by interpolation between the deflections in the limit states according to the acting moment level.
10.14359/6786
SP76-06
G. Chadha
A precise evaluation of prestress losses in prestressed concrete members is a simple but time-consuming problem. Nevertheless, design aids would be useful to engineers. This paper uses an iterative procedure for calculating the long-term losses. Tables for direct prediction of losses due to creep and shrinkage are presented. It uses available information on concrete creep and shrinkage and steel stress relaxation, and includes the effect of interaction of various factors contributing to the prestress losses. To illustrate the use of the tables, two numerical examples are included. The tables are applicable for all prestressed concrete structures such as buildings, bridges, or nuclear power plants. The manual computations being tedious and time consuming, the predicted prestress losses tables are highly accurate, as they are based on interaction computer program using increments of short duration.
10.14359/6787
SP76-07
M. S. Khalil, W. H. Dilger, and A. Ghali
A computer-aided, step-by-step method is presented for the study of time-dependent stresses and deformations of pre-stressed concrete frames. The method is used to investigate the effectiveness of deferring the final connections between column or walls and slabs in building frames and allowing the slabs to slide on the columns during post-tensioning. The joints are then constructed at a later date. A second investigation concentrates on the stresses developed in a cast-in-place, normally-reinforced closure strip cast sometime after post-tensioning of the floors in a long continuous frame. Results obtained for the two examples are evaluated and the possibility of excessive stresses and cracking is discussed.
10.14359/6788
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