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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 16 Abstracts search results
Document:
SP90-14
Date:
April 1, 1986
Author(s):
Muthia Kasi
Publication:
Symposium Papers
Volume:
90
Abstract:
In the last systematic review of reinforced concrete column costs in 1973, ACI Committee 439 limited its cost comparisons to concrete strengths from 4000 to 8000 psi and reinforcing steels with design yield of 60,000 psi with speculative estimates of steel with 80,000 psi yield. Design then was based upon the 1971 ACI Building Code. At that time the leading structural engineers had successfully utilized concrete with f'c = 9000 psi under the current code. A number of general conclusions on costs were presented as trends. To bring this review of reinforced concrete column costs up to date, we must consider changes in code requirements, more general availability of still higher strength concretes, superplasticizer admixtures, building code limitations and general lack of economy in a Grade 80 reinforcement, and later laboratory testing and field research on properties and performance of high-strength concretes. A recent detailed comparative cost study of reinforced concrete columns which resulted in appreciable cost savings in a Chicago high-rise building, reinforces some of the 1973 report under conditions today. As might be expected in dealing with the numerous variables involved in comparative column design costs, the detailed study was made effective only through a computer program. The essential features of this program are described in detail in the CRSI Bulletin.
DOI:
10.14359/1776
SP90-15
John G. H. Harrison
The new World Headquarters Building for Elf Aquitaine in Paris, France was designed by a Canadian architectural firm who won the commission in an invited design competition in 1979. Work on construction documents began in Paris in January 1981 and construction began early in 1982. Bouyges, the contractor for the reinforced concrete structure, undertook extensive studies to develop a special formwork system for the facade structure since there is little if any background of experience to draw on in France in the construction of high-rise buildings. At 48 stories this was a building of very significant height and would require a whole new approach. The result of these studies was a very ingenious system of facade forms, fabricated entirely in steel and consisting of column and beam forms, complete with integrated working platforms, access ladders, and 2 story high protective mesh screens. A system of alignment nibs insured faithful adherence to the allowable tolerances both vertically and horizontally. Although the research and capital costs were significant, substantial cost savings were nevertheless made in the erection of the structure both in time and labor thus confirming the validity of this formwork design.
10.14359/1777
SP90-11
N. J. Gardner and Chi-Seng Chan
Multistory reinforced concrete structures are generally constructed using one level of shores and multiple levels of reshores. The stripping schedule is to completely strip a bay of shores before reshoring. Reshoring results in high-early-age construction loads being applied to the immature slab structures. Preshoring, or scheduled reshoring, is an attempt to reduce the adverse effects of clear bay reshoring by reducing the area stripped before reshoring. The load-strength ratio in preshored construction is little different to reshored construction but the loads are applied later which will reduce creep deflection effects. Using 2D and 3D models the slab, shore, and reshore loads were calculated for preshored construction. The advantage of preshoring is that the unsupported span lengths are reduced thus reducing slab deflections. The disadvantage of preshoring is that to realize the benefits close control of the construction process is needed.
10.14359/1773
SP90-05
Harry B. Lancelot.
Dowel bar substitution is a new phrase but not a new solution. The technique provides a productive means of splicing across construction joints. Examples of the application are shown and discussed in this article.
10.14359/1769
SP90-01
Russel S. Fling
Economy in concrete construction is discussed in light of 3 challenges: 1) the challenge of economizing design, 2) the challenge of economizing construction, and 3) the challenge of standardizing construction. Procedures engineers may use to reduce the cost of construction are given. Suggestions for standardizing concrete construction include standards for concrete classes, column sizes, column spacing, column capitals, and tolerances.
10.14359/1765
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