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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 11 Abstracts search results
Document:
SP129-10
Date:
December 1, 1991
Author(s):
Yun-Soo Joo and Maher K. Tadros
Publication:
Symposium Papers
Volume:
129
Abstract:
The objective of the paper is to develop a computer-based procedure for analysis of members made up of precast prestressed concrete sections with cast-in-place topping. The procedure accounts for cracking under the weight of the cast-in-place topping and superimposed loads. Creep and shrinkage of concrete and relaxation of prestressed steel are taken into account in combination with the effects of cracking. An attempt is made to limit the input data to information commonly available to designers. Linear creep law is used, and time-dependent effects, such as prestress losses and deflection growth, are automatically generated.
DOI:
10.14359/1257
SP129-08
B. L. Meyers and M. A. Daye
Pressurized water reactor containment building structures in nuclear power plants are designed to withstand internal accident pressure. Prestressed concrete is commonly used to resist such a pressure. The structure must maintain its structural integrity for the service life of the plant; therefore, the design must consider the effect of creep and shrinkage of concrete on the prestressing system. This effect is mainly in the form of prestressing force losses over time. Since creep and shrinkage are time-dependent, their values at any point in time during the service life of the plant must be predicted. The approach utilized in the design of the prestressed containment structure and the required periodic inspection are described. Also addressed is the procedure for establishing predicted changes in the prestressing forces as a result of creep and shrinkage of concrete at any point in time. Comparisons between predicted values and actual measurements of prestressing forces at different time intervals are presented. The comparison includes a number of reactor containment buildings and different concrete proportions.
10.14359/1286
SP129-09
Mehdi S. Zarghamee and william R. Dana
A step-by-step procedure is used for computing the state of stress in a prestressed concrete cylinder pipe accounting for the effects of creep and shrinkage of concrete core and mortar coating and of wire relaxation. The procedure is applied to an embedded-cylinder pipe subjected to the outdoor environment and to that of a buried pipe with varying humidity conditions. The results show that for pipe exposed to the outdoor environment, the prestress in the inner and the outer cores of embedded-cylinder pipe are significantly different. However, the change in the environment resulting from burial of the pipe and filling it with water reduces the losses, and the difference in the prestress of the inner and the outer core of embedded-cylinder pipe.
10.14359/1287
SP129-03
N. C. Mickleborough and R. I. Gilbert
The first stage of an experimental investigation into the instantaneous and time-dependent behavior of reinforced concrete columns under sustained load is reported. The experimental work described in the paper involves the testing of 15 large-scale columns in compression and uniaxial bending to obtain comprehensive creep deformation data for the prediction of long-term lateral deflection and instability. Information on the range of slenderness ratios and load levels which cause creep instability for rectangular symmetrically reinforced concrete columns is of particular interest. The experimental data is also for use in the development and calibration of a theoretical model for the prediction of creep deflection and buckling under sustained load. The experimental setup used in this investigation and described in the paper is designed for the simultaneous testing of five slender columns, each up to 6 m in length. The loading frame is such that each column may have different length, different cross-sectional dimensions and reinforcement details, and be subjected to different combinations of axial force and bending moment. In the three series of tests presented here, column length, axial force, and initial eccentricity are the major variables. The loading on each column is monitored independently and maintained automatically at a constant preset value throughout each test. A direct comparison of creep effects on column behavior is therefore possible as different loading parameters are varied.
10.14359/1254
SP129-04
B. Vijaya Rangan
The paper presents a summary of treatment of deflection control in the Australian Standard, AS3600-1988. The top-tier method recommended by the standard requires consideration of creep and shrinkage effects on deflections. Simple expressions for calculating creep and shrinkage deflections are given and illustrated by examples.
10.14359/1255
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