International Concrete Abstracts Portal

SP97 This publication is a collection of 12 papers detailing the new and definitive techniques that have made possible the construction of milestone buildings in high-rise construction. The "Chicago style" of construction and the concepts developed by the Chicago design and construction teams in the science of high-rises are covered in this publication. Topics covered include: high-rise system developments in concrete; prestressed concrete in high-rise construction; recent developments in deep foundations for high-rise buildings; and simplified design of slender unbraced columns. Analysis and Design of High-Rise Concrete Buildings offers a wealth of information on concrete technology such as high strength, lightweight, fiber reinforced, corrosion-resistant, and impermeable concretes that have been utilized to make possible some of the tallest buildings in the world.

The Chicago Department of Inspectional Services, otherwise known as the Department of Buildings, has the same mission as any other Building Department in the country--namely, to protect public safety, health, and property. As a department, it is not small in size or force, but not too large either. It is no more wasteful than any other government office. It is, however, rather effective in its mission. It does provide valuable services to the public with courtesy and speed and does have some progressive fea-tures both in its organizational makeup as well as in the manner of providing its services.

The ready-mix concrete for high-rise structures in Chicago is unique in reference to the special concretes that have been developed for this type of construction. However, the overall picture of the ready-mix industry is similar to what is happening to the ready-mix industry in other areas of the world. The ready-mix concrete business is a dynamic resource for the construction industry, which must periodically reevaluate its position in relation to the economy, the nation, local industry, and especially with the customer. Highly-developed economies bring changes in market conditions. A change which has been occurring is the change from a product to a service-related market. This change occurs earlier in mass consumer products and lags behind in more static products like those in the construction industry. This conversion from product to service is taking place now in the construction industry. The ready-mix industry has traditionally made its profit in the volume of regular concrete with strengths from 3000 to 5000 psi. This is a product that does not require special quality control or special technology, consequently it can be handled by concrete technicians and salesmen with limited technical knowledge. This is also a product which does not require special promotion, is simple for code compliance, has abundant analysis and design information for the users, and does not require special mixing and transportation equipment. It is not difficult to sell when the price is right. It is usually sold with a questionable margin of profit which will continue diminishing until management makes the decision to make some changes. Management realizes that the ready-mix industry cannot survive in the mature economy of large metropolitan areas where the large concentration of ready-mix producers and their geographical proximity has brought their profit to a minimum return on their investment. Consequently, the search for changes becomes imperative to survive in a highly technological and competitive economy. However, changes are expensive in this high capital industry. The changes required to bring the ready-mix industry to high-technology levels are expensive because they involve management, equipment, quality control and marketing concepts. Aside from being expensive, they are difficult to accomplish because they require a total commitment from management and a clear understanding of a long range plan for its proper implementation.

This text is the product of a collaborative effort by the concrete construction services staff of Ceco Industries, inc. Many staff members contributed their findings and recommendations, which were organized and integrated by William R. Anthony, PE, Manager, Market Development. Through its subsidiaries, Ceco Industries is a national formwork subcontractor, and provides the preconstruction services of value engineering, systems analysis and budget pricing. In a growing number of markets, Ceco also provides a total concrete building frame contracting service.

As the speed of construction of concrete frame structures has increased and the sophistication of design has improved, there has been an increased need for a more thorough understanding as to the way construction loads are disbursed into the structure. During the 60's and 70's, several designers and researchers proposed methods of analyzing the loads in multi-story structures during construction. A computer program employing one of these methods has been developed. In the 1982 PCA conference,the author used the results of this program to show how the number of levels of equipment, cycle time, and attained concrete strength affected the number of levels of reshores required. This paper describes in detail the process used to calculate the reshoring requirements for a 359-story flat plate structure built using a three-day construction cycle. The discussion includes the practical implications of providing reshoring for a mild steel structure. The hand calculation procedure presented parallels the computer program and is sufficiently detailed to provide the reader a practical procedure that can be used on the next project.