International Concrete Abstracts Portal

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.

SP78 A collection of 15 papers on foundations for equipment and machinery, covering design and research. The topics include: baseplate grouting, elevated foundations for reciprocating machines, case studies of machine foundations under dynamic loads, pile supported machines, turbine pedestal structure, and more.

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.

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.

Grout, shims, or both, plus anchors form the vital link between machines, equipment, and column bases and their foundations. Grout and/or shims hold the equipment up and anchors hold it down. Grout, as used in this paper, is any fluid, flowable, plastic, or packable material that can be used to fill the space between the underside of a machine or column and the foundation on which the unit is to rest, then harden there to support the unit. The most widely used materials for grouts are combinations of hydraulic cements, fine aggregates including graded iron particles, various additives including chemical admixtures, and water. In recent years, various epoxy combinations with and without suspended fine aggregate have also been employed. This paper discusses hydraulic cement base grouts that are intended to not only completely fill the space under a base plate initially, but also harden in tight contact with the plate and permanently support or participate in the support of that plate. Such grouts are generally referred to as "nonshrink." Reasonably obtainable properties that the engineer may require of such a grout and tests he may specify to assure the results he desires are described. The pluses and minuses of fluid, flowable, plastic, and dry-pack grouts are covered and techniques for placing grouts at each consistency are described and illustrated. A measurable definition of the terms fluid, flowable, plastic, and dry-pack is offered.