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International Concrete Abstracts Portal

Showing 1-5 of 16 Abstracts search results

Document: 

SP78-03

Date: 

January 1, 1982

Author(s):

Gary R. Hall, George W. Read, Jr., and R. L. Trinklein

Publication:

Symposium Papers

Volume:

78

Abstract:

The properties of portland celllent based nonshrink grouts are discussed. A review of the basic engineering concepts involved is presented. A brief discussion on the chemistry involved in grout technology is presented. Performance criteria are discussed in some detail, along with methods of testing for the perfortilance criteria. A brief description of the various grouting systems available to the market place is presented.

DOI:

10.14359/16904


Document: 

SP78-01

Date: 

January 1, 1982

Author(s):

Suresh C. Arva and George Pincus

Publication:

Symposium Papers

Volume:

78

Abstract:

Most reciprocating machines are critical to the operation of the plant and, therefore, the sr~pporting structure must be carefully designed to avoid potential undesirable behavior such as attainment of a resonance condition. The designer is then confronted with selecting the best possible techniques in order to accomplish a trouble- free condition. Available engineering analysis tools include theory of vibrations, half-space theory, soil-structural analysis computer programs and rational modeling techniques. This paper summarizes and reviews the steps that must be considered during design of the supporting structure for an elevated reciprocating machine and provides practical guidelines which serve to obtain a realistic and useful design. Four different models are presented and discussed and an example problem is used to illustrate the main features and results of each model. It is concluded that the combination of the best modern scientific tools and modeling technique coupled with practical guidelines yields a reliable structural configuration.

DOI:

10.14359/16902


Document: 

SP78-02

Date: 

January 1, 1982

Author(s):

Donald E. Baxa and Robert Ebisch

Publication:

Symposium Papers

Volume:

78

Abstract:

This paper is a case study of pneuniatic isolation systeliis in large automobile recycling machines. Machines of increasing size and power, plus a public that is increasingly insistent on its right to an environment free of noise and vibration, equal potential problenis for recycling plants. In response to this situation, a hammermill/shredder operation making successful use of pneunlatic isolation has been designed and constructed. The first, and still the largest, operation of its kind, the operation has demonstrated a valuable method of containing machine vibrations that might otherwise ignite hostility in the surrounding community and quite possibly bring on expensive legal action. The particular system described was installed in a 4,000-horsepower hammermill at an Indiana recycling firm. Besides effecting a more than 90 percent reduction in ground vibration, the system allows for easier and more efficient machine leveling and includes systems to warn of and localize pressure loss, to minimize routine mechanical shock, and to contain extraordinary shocks resulting from exploding gas tanks and loss of hammers within the machine. The system has now been in use for two years with no reported problems.

DOI:

10.14359/16903


Document: 

SP78-09

Date: 

January 1, 1982

Author(s):

Herbert A. Franklin

Publication:

Symposium Papers

Volume:

78

Abstract:

This paper describes the design and construction of low-tuned, spring supported foundations for boiler feedpumps units installed in the Big Stone coal-fired power plant in South Dakota. Each system consists of a variable speed 9,500 HP (7084 Kw) steam turbine which drives a pair of feedpumps and is mounted on a prestressed concrete inertia block set on steel springs. This vibration isolation design required dynamic analysis of the inertia block systems since the variable speed pumps could present a range of forcing frequencies and hence a series of possible resonances. The concrete inertia blocks were prestressed in order to prevent cracking which could cause significant changes in the dynamic behavior. The concrete inertia blocks were fabricated and prestressed outside the turbine building. Each weighed about 96 tons (854 kN) and they were lifted into position on their steel springs on the operating floor level. The flexible isolation of the inertia blocks from the building floor facilitated the alignment of the machinery and the attachment of the piping. Vibration tests were conducted during plant start-up in order to anticipate potential problems and to verify dynamic characteristics. These units have now performed successfully for several years.

DOI:

10.14359/16910


Document: 

SP78-10

Date: 

January 1, 1982

Author(s):

Michael J. O'Rourke and Ricardo Dobry

Publication:

Symposium Papers

Volume:

78

Abstract:

This paper presents a simplified procedure for calculating the equivalent stiffness and clamping of a pile supported machine foundation. Separate procedures are developed for the case where there is a small gap between the bottom of the pile cap and the soil surface (Gap Case) as well as the case where there is continuous contact at all times between the bottom of the pile cap and the soil (No Gap Case). The horizontal and vertical spring constants are developed using beam on elastic foundation concepts. Both material and geometric damping contribute to the dashpot coefficients. The radiation or geometric dashpots are developed from wave propagation considerations. The equivalent springs and dashpots for individual piles in the Gap Case compare well with corresponding values obtained from a dynamic finite element program.

DOI:

10.14359/16911


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