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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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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 11 Abstracts search results
March 1, 1995
E. J. Ulrich Jr., and C. J. Ehlers
The St. Luke's Medical Tower is the Texas Medical Center's tallest building and Houston's tallest building to open the 1990s. The combination of the following unique foundation features reduced development costs by over $1,000,000: (1) tallest soil-supported building on shallow foundations in the Southwest; (2) temporary dewatering system designed to function as the permanent system; (3) excavation-bracing system designed to form the permanent basement wall and only individual braces were temporary; (4) basement walls esigned to accept loads from future contiguous towers; (5) drilled pier soldier piles installed with polymer drilling fluid (the first use on a major Texas project); and (6) drill pier soldier piles installed in accordance with the new American Concrete Institute Standard Specification for the Construction of Drilled Piers (ACI 336.1-89), the first known use of the specification. The factored load condition was considered fictional in foundation, and basement wall design in that factored load-concrete-subgrade compatibility was not achieved. Significant cost savings was achieved by allowing the geotechnical engineer to be part of the design team beginning with project concept studies and extending throughout underground construction. The geotechnical engineer and the team developed feasible foundation schemes that could be integrated into construction needs, instead of relying only on specialty design builders.
J. P. Stewart, K. H. Pitulej, and H. S. Lacy
Describes the design of a load-compensated mat foundation on highly compressible soil. The mat was used to support over 800,000 square feet of variable height building. While the design of the mat was mostly routine, the behavior at the mat edges was difficult to determine. The deformations at mat edges were the major concern since they were influenced by the need to raise grades around the building perimeter. The design procedure incorporated soil-structure interaction analysis to determine the extent of lightweight fill zones required to control edge deformations. Settlement monitoring over a period of two years has confirmed the design approach.
A. R. Dar
In large concrete pours, the heat of hydration, which continues to build for several days, is a major cause of concern for structural engineers. As the surface of concrete cools off, a thermal gradient is formed across the concrete section which can cause the concrete to crack. This paper verifies that by keeping concrete warm and preventing heat from escaping rapidly, the temperature difference within the mass can be minimized, thus reducing the potential for thermal cracking. Use of this technique made possible the largest monolithic mat foundation pour in Hawaii, without construction joints and without artificial cooling of concrete.
E. J. Ulrich, JR.
Subgrade response is the most important parameter in analyzing and designing mat foundations. Rational design of a mat foundation requires consideration of immediate and long term subgrade response. The soil response determines mat behavior, and differential movement exacerbates moments. Often, long term movement provides the most severe mat behavior characteristics. The popular use of a single modulus of subgrade reaction k, to model subgrade response is wrong and will lead to wrong designs. Mat analysis and design should be performed using the discrete area method, in which subgrade responses can be properly modeled because of the use of varying moduli of subgrade reaction. The geotechnical engineer and the structural engineer must form a solid bond to cope with mat foundation design from early planning through construction; both must work together to assure successful performance. Often, construction details and procedures will govern performance and can ruin any analysis. For this reason, the geotechnical engineer should be on site accessing conditions.
C. N. Baker, Jr.
Describes three innovative mat foundation designs and the close interaction required between the structural engineer and the geotechnical engineer. The significance of load deformation prediction reliability in the three different soil profiles is illustrated. The cases reviewed include a three-story office building with single basement build on a mat over peat; a 26-story apartment building with basement built on a modified mat in a thin dense sand stratum over soft clay; and a 19-story hotel with two basements built on a mat in a sand layer over medium clay. The mat of the 19-story hotel was supplemented with selective high capacity piles at the column locations designed to ultimate soil capacity at working loads and utilized to reduce both mat settlement and design mat thickness. The instrumentation used to confirm design assumptions in the three cases is briefly described.
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