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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 26 Abstracts search results
Document:
SP55-11
Date:
August 1, 1978
Author(s):
Boris Bresler and Robert H. lding
Publication:
Symposium Papers
Volume:
55
Abstract:
Prediction of the response of reinforced concrete structures to variations in temperature, humidity, and load is described. Modeling of structures, loading history, environment, and material behavior is discussed and several case studies are included to illustrate the use of proposed models. The models account for nonlinear behavior under variations in load and environment and for the non-homogeneity introduced by steel reinforcement and cracking of concrete.
DOI:
10.14359/6617
SP55-12
Kin Leung Lai and Robert F. Warner
An analytic study was made of the effects of creep andshrinkage in lightly loaded continuous girders and frames by means of computer programs which were developed to simulate the timevarying behavior of a structure under sustained variable loading. Variations in the internal moments with time were found to be very large, a 50 percent increase or decrease in the maximum moment being not unusual. Concrete shrinkage was found to have a much more important effect on long-term moment redistribution than creep. The quantity and distribution of reinforcement also had a critical effect, both on moment redistribution and long-term deflection.
10.14359/6618
SP55-13
Ian J. Jordaan and Magdi M.A. Khalifa
The time-dependent behaviour of concrete structures subjected to thermal gradients and, in addition, to mechanical loading is considered. Redistribution of stress with time results from two kinds of nonhomogeneity; firstly, there is a stress transfer from concrete to steel and secondly, the spatial variation of creep parameters (resulting from the temperature variation) causes stress redistribution. The constitutive laws for concrete creep are discussed in the light of recent experimental findings and a simple constitutive equation is found to account for the major features with sufficient accuracy in the analysis of static temperature fields. Because of the form of the equation, viscoelastic methods can be used; based on this fact, two approximate methods are proposed. Both use effective modulus calculations which must incorporate a spatially varying elastic modulus to account for the spatially varying creep properties; this is easy to achieve through the use of the finite element method. Two examples are given; the first is a reinforced cylinder subjected to internal pressure and a temperature gradient and the second is concerned with prestressed beams subjected to external loads and a temperature gradient. A comparison of the approximate methods with step-by-step calculations is given and good agreement is demonstrated.
10.14359/6619
SP55-14
H.G. Russell and W.G. Corley
An 859-ft building was instrument deformations of column of individual member displacements were measured (262 m) high reinforced concrete ted to m easure the time-dependents and walls. Vertical shortening S and their relative vertical sured at selected floor levels. Laboratory tests were the field. The elastic modulus, coefficients and shrinkage with age each different concrete laboratory tests and vertical shortening of values were compared performed on concrete obtained in iation 0f compressive strength, icient of thermal expansion, creep, of conc rete were determined for rete st rength. Based on the detailed construction records, the column S was calculated. These with those measured in the building.
10.14359/6620
SP55-15
R.N. Swamy and P. Arumugasaamy
The long-term movements of in-situ reinforced concrete columns in two structures are reported through the construction stage to occupancy and subsequently in service. The columns were extensively instrumented to measure strains, temperature and moisture changes; in addition, a stress meter was incorporated in the second structure at the base of an internal column to relate the field movements and their effects to the load actually carried by the column. The results show that the inelastic movements in concrete cause a gradual load transfer to the steel reinforcement. In one structure steel stresses in excess of the permissible design values were noted. The assumed design dead load components of the working loads were realized in the lower columns of the structure but not in the upper storeys. After nearly five years in service, the concrete in the columns of the second structure were found to carry loads varying from 50% to 80% of the measured load carried by the columns. It is shown that a major proportion of the loads carried by the columns result from dead loads and that only about 10%-20% of the total design loads constitute imposed loads.
10.14359/6621
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