The design of foundations to support large items of mechanical equipment is becoming increasingly important. In many industrial environments the consequences of vibration are severe. For example, sensitive processes can be rendered inoperable, process and mechanical equipment can be damaged, and work conditions can become intolerable. This paper reviews the design and performance of a number of equipment foundations subjected to dynamic loads. The case histories presented typify the types of foundations and dynamic loads commonly encountered in industrial environments. Included are both mat and piled footings, and foundations supported on drilled piers. Fans and compressors are representative of the types of equipment discussed. It is the intent of this paper to present guide- lines for the design of equipment foundations where dynamic loads are involved. The paper reviews the various analytical approaches available to the designer, and those factors which influence the development and choice of a suitable analytical model. Primary emphasis is placed on the development of nonresonant designs. Other topics presented include, limits placed on displacement amplitudes, damping, the effects of foundation geometry and mass distribution, and allowable soil bearing pressures.

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.

A dynamic analysis of an Induced Draft Fan and Foundation, subjected to unbalanced rotor loadings, is described and discussed. The installation selected for analysis is supported on piles, and consists of a reinforced concrete foundation and bearing pedestals, fan motor, fan, housing, and exhaust duct (evase’). The modeling techniques presented by the author in this case study will illustrate a method for the Design Engineer to completely analyze complex coupled systems involving both oil film and pile/soil stiffness and damping. The techniques presented do not require that the structural analysis computer program have discrete element damping (dashpot) capabilities. The model is all inclusive and can be used for both static and dynamic analysis. Dynamic responses, particularly modal frequencies and peak-to-peak journal bearing amplitudes of motion are compared with those calculated from relatively simplified lumped mass stick models of the same installation. Insight is gained into the dynamic behavior of the coupled system and the comparison study points out the limitations of the stick model responses. This paper presents a case study of an Induced Draft Pan and Foundation with special emphasis on the computer modeling techniques utilized. The model illustrated idealizes the COMPLETE system installation, and as such, is capable of directly predicting static deflections and internal forces, as well as coupled dynamic responses to earthquake and unbalanced rotor loads. The modeling techniques described are readily adaptable to commercially available structural analysis programs with finite element capabilities (i.e., Nastran, Strudl, Stardyne, Ansys).

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.

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.