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Showing 1-5 of 16 Abstracts search results

Document: 

SP78-11

Date: 

January 1, 1982

Author(s):

Gerald M. Diaz and Mir Azizi

Publication:

Symposium Papers

Volume:

78

Abstract:

Past attempts to analyze pile supported foundations included many simplifying assumptions regarding the pile-soil impedence functions (stiffness and damping) for a single pile. Further simplification was required to evaluate the effects of the pile group. In recent years significant studies relating to pile-soil dynamic behavior have been made and good agreement was reported in comparison with relatively small scale field tests. Also, generalized analyses of pile groups have been developed. In this paper the authors have used what they consider to be the current State-of-the-Art techniques for evaluating pile-soil impedence functions, group behavior, and embedment effects to calculate the dynamic response of pile supported machines and compared the calculated results to actual field measurements. Three similar operating plants, each using an identical reciprocating large compressor, were the basis of the study. The soil investigations included in-situ measurement of dynamic properties. The soil conditions at the sites were such that all sites required pile foundations and different pile types, including friction and end bearing piles, and batter piles. The results indicate that good agreement is achieved using the methods proposed for the rocking, and horizontal and vertical translation modes of vibration. .Further analyses are recommended to further investigate the behavior in the torsional mode. Also, further comparisons should be made with actual foundations where vibrations could be monitored at varying frequencies.

DOI:

10.14359/16912


Document: 

SP78-15

Date: 

January 1, 1982

Author(s):

A. Rajaraman and C.V. Vaidyanathan

Publication:

Symposium Papers

Volume:

78

Abstract:

In the design of frames supporting machines inducing harmonic excitations, the frequency level is a major consideration. Altering this level - called tuning - requires the change in design parameters. This study presents results by introducing a new parameter - taper - so that existing frames could be tuned properly or in many cases redesigned to take up increased speeds of machinery. The results are given in tabular form for ready reference.

DOI:

10.14359/17527


Document: 

SP78-13

Date: 

January 1, 1982

Author(s):

P. N. Fletcher and K. Y. Lee

Publication:

Symposium Papers

Volume:

78

Abstract:

This paper presents a new concept in designing a structure which is used as falsework, and utilized as reinforcing, which incorporates construction features for a turbine generator supporting structure. The turbine generator is supported by a massive concrete structure. In order to eliminate the falsework required for supporting the fresh concrete at the operating floor level, steel trusses are embedded in the concrete beams. The stress in the truss chord members are low for the construction loading, thereby allowing the trusses to be used as reinforcing in the beams. The trusses can be shop assembled in modules which can be transported by rail or truck to the site. In the assembly yard, the modules are completed for transporting to the turbine generator area and placing on the pedestal columns. The complete operation consists of adding side and soffit forms, rebar, anchor bolts, embeds, embedded conduits and penetrations. This construction sequence allows the turbine building outer framework to be erected prior to the placement of concrete pedestal. An enclosed building will also provide better control and environment for placing the concrete in the pedestal. This paper will provide an example pedestal design for a 1200Mw turbine generator. The details of fit-up of the truss modules, erection sequence, type of materials used, typical detai1s and concrete placement will be presented.

DOI:

10.14359/16914


Document: 

SP78-08

Date: 

January 1, 1982

Author(s):

P. Srinivasulu and N. Lakshmanan

Publication:

Symposium Papers

Volume:

78

Abstract:

In the first part, the paper critically reviews the current state of art on the analysis and design of typical types of machine foundations. The uncertainties in the design data and paucity of essential information required for a rational design are highlighted. The need to study the geotechnical features and other environmental factors at the proposed site of a machine foundation is emphasized. The various aspects of the problem of a machine foundation are illustrated with the explanation of five typical case studies selected from authors' experience in this line of work. The paper also underlines the need for a close co-ordination between the civil and mechanical engineers responsible for the installation of machine foundation right from the early stages of planning.

DOI:

10.14359/16909


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


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