ACI R (FEA Method). Input Data. Machine Data. Foundation Type = Single Block. Machine Type = Rotating Machine. Resonance Limit. ACI codes for dynamic equipment foundation by radhitya_himawan. ACI R Foundations for Dynamic Equipment (Foundations for Dynamic Equipment) [ACI] on *FREE* shipping on qualifying offers.

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This report presents to industry practitioners the various design criteria 2. Chapter 3—Design criteria, p. This document is intended for the use of individuals who are 4. The American Concrete Institute disclaims any and all responsibility for the stated principles.

The Institute shall not Chapter 5—Construction considerations, be liable for any loss or damage arising therefrom. ACI does not make any representations with regard to health and safety issues and the 5. The user must determine the applicability of all regulatory limitations before applying the ACI Rotating machinery; individual cylinder load carried by the 2. Impact or impulsive machinery. Economic factors such as capital cost, useful or antici- as given in Table 4. This dynamic force is a function tational acceleration of the shaft mass, speed of rotation, and the magnitude of the offset.

Individual inertia forces from each cylinder and each throw are inherently unbalanced with dominant frequencies at one and two times the rotational frequency Fig. Reciprocating machines with more than one piston require a particular crank arrangement to minimize unbalanced forces and moments.

A mechanical design that satisfies operating requirements should govern. Individual cylinder fluid forces act outward on the cylinder head and inward on the crankshaft Fig.

For a rigid cylinder and frame these forces internally balance, but deformations of large machines can cause a significant portion of the fluid load to be transmitted to the mounts and into the foundation. Particularly on large reciprocating compressors with horizontal cylinders, it is inappropriate and unconservative to assume the compressor frame and Fig. Such an assumption has led to many inadequate mounts for reciprocating machines. This shock loading is often transmitted to the foundation system of the equipment and is a factor in the design of the foundation.

Closed die forging hammers typically operate by dropping a weight ram onto hot metal, forcing it into a predefined shape. While the intent is to use this impact energy to form and shape the material, there is significant energy transmission, particularly late in the forming process. During these final blows, the material being forged is cooling and less shaping takes place.

Thus, pre-impact kinetic energy of the ram converts to post-impact kinetic energy of the entire forging hammer. As the entire hammer moves downward, it becomes a simple dynamic mass oscillating on its supporting Fig. This system should be well damped so that the oscillations decay sufficiently before the next blow.

Timing of the blows commonly range from 40 to blows per min. Dynamic forces from are common. Open die hammers operate in a similar fashion the press develop from two sources: Forging presses perform a similar manufacturing function Imbalances in the mechanics of the equipment can occur both as forging hammers but are commonly mechanically or horizontally and vertically.

Generally high-speed equipment hydraulically driven.

R Foundations for Dynamic Equipment (Reapproved )

These presses form the material at low is well balanced. Low-speed equipment is often not balanced velocities but with greater forces. The mechanical drive because the inertia forces at low speeds are small. The system generates horizontal dynamic forces that the engineer dynamic forces generated by all of these presses can be should consider in the design of the support system.


Rocking significant as they are transmitted into the foundation and stability of this construction is important. Mechanical metal forming presses operate by squeezing While part of the dynamic load from these types of equipment and shearing metal between two dies.

The ability to use such a foundation primarily depends on the quality of near surface soils. Block foundations are nearly always designed as rigid structures. Combined blocks are used to support closely spaced machines. Combined blocks are more difficult to design because of the combination of forces from two or more machines and because of a possible lack of stiffness of a larger foundation mat.

Elevation allows for ducts, piping, and ancillary items to be located below the equipment. Tabletop structures are considered to be flexible, hence their response to dynamic loads can be quite complex and depend both on the motion of its discreet elements columns, beams, and footing and the soil upon which it is supported.

The effectiveness of isolators depends on the machine speed and the natural frequency of the foundation. Details of this type of support are provided in Section 4. The springs are then supported on a block-type foundation.

This arrangement has a dynamic effect similar to that for tabletops with vibration isolators. Other types of equipment are spring mounted to limit the transmission of dynamic forces.

In this situation, dynamic machines random character to the dynamic signal that varies with the are usually designed with a supporting inertia block to alter particular operation.

Other limiting dynamic criteria affecting the design may include avoiding resonance and excessive trans- missibility to the supporting soil or structure.

Thus, a key ingredient to a successful design is the careful engineering analysis of the soil-foundation response to dynamic loads from the machine operation. Consequently, critical soil parameters, such as the dynamic soil shear modulus, are preferably determined from a field investigation and laboratory tests rather than relying on Fig. Due to the inherent variability of soil, the dynamic response of machine foundations is often evaluated using a range of values for the critical soil properties.

Furthermore, a machinery support structure or foundation is designed with adequate structural strength to resist the worst possible combination of loads occurring over its service life. This often includes limiting soil-bearing pressures to well within allowable limits to ensure a more predictable dynamic response and prevent excessive settlements and soil failures.

Piles use end bearing, 3. Transverse loads are turbines, generators and motors, presses, and other machinery resisted by soil pressure bearing against the side of the pile should withstand all the forces that may be imposed on them cap or against the side of the piles.

Various types of piles are during their service life. Machine foundations are unique used including drilled piers, auger cast piles, and driven piles. The magnitude and charac- 3. Yet, behind this straightforward definition lies the priate values for dynamic loads is best accomplished through need for careful attention to the interfaces between machine, careful communication and clear understanding between the mounting system, and concrete foundation. Static loads are principally a function of the and the definition of the information provided.

It is in the best weights of the machine and all its auxiliary equipment. The magnitude of these dynamic loads tion, and force transmitted through the bearings. The machine manufacturer and foundation parts within the casing. Allowable amplitudes Sections 3. The weights of the machine compo- for design of nonstructural components, including dynamic nents are normally supplied by the machine manufacturer.

The machinery, for seismic loads. For machinery supported distribution of the weight of the machine on the foundation above grade or on more flexible elevated pedestals, seismic depends on the location of support points chocks, soleplates amplification factors are also specified.


In many cases, the machine manufac- during normal operation and forces, such as the drive torque turer provides a loading diagram showing the vertical loads at developed by some machines at the connection between the each support point. When this information is not available, it is drive mechanism and driven machinery. Static operating common to assume the machine frame is rigid and that its loads can also include forces caused by thermal growth of weight is appropriately distributed between support points.

The live loads operation are covered elsewhere in this report. For most designs, live loads are some form of drive mechanism, either integral with the uniformly distributed over the floor areas of platforms of machine or separate from it.

When the drive mechanism is elevated support structures or to the access areas around at- nonintegral, such as a separate electric motor, reciprocating grade foundations.

The torque is equal in maintenance equipment and materials. The normal torque sometimes called drive torque areas of the machine, auxiliary equipment, and the support is generally applied to the foundation as a static force couple foundation are based on the design wind speed for the partic- in ai vertical direction acting about the centerline of the ular site and are normally calculated in accordance with the shaft of the machine.

The magnitude of the normal torque is governing local code or standard.

351.3R-04: Foundations for Dynamic Equipment (Reapproved 2011)

Wind loads rarely govern often computed from the following formula the design of machine foundations except, perhaps, when the machine is located in an enclosure that is also supported by P s the foundation.

When the described in ASCE 7 for flexible structural systems. Normal torque facilities requirements. In this case 3. Startup torque, a property of electric motors, should be obtained from the motor manufacturer.

The torque created by an electrical short circuit is considered a malfunction, emergency, or accidental load and is generally reported separately by the machinery manufacturer. Often in the design for this phenomenon, the magnitude of the emergency drive torque is determined by applying a magnification factor to the normal torque.

Consultation with the 35.13r-04 manufacturer is necessary to establish the appropriate magnification factor. These forces are additive to normal gravity loads and are considered to act at the centerline afi the machine shaft. Loads 1, 2, and 3 are not considered to act concurrently with one another. Erection loads are usually furnished in the manufac- The friction coefficient generally varies 351.3r04 0. Maintenance loads occur any time 315.3r-04 equipment is Heat transfer to the foundation can be by convection across an being drained, cleaned, repaired, and realigned or when the air gap for example, gap between sump and block and by components are being removed or replaced.

Loads may conduction through points of physical contact. The resultant result from maintenance equipment, davits, and hoists. Envi- temperature gradients induce deformations, strains, and stresses. As the thermal forces are to slide on the 351.3-04 surfaces. The magnitude of the resulting frictional forces depends on the magnitude of the applied to the foundation member by the machine, the foun- temperature change, the location of the supports, and on the dation member changes length and thereby provides reduced condition of the support surfaces.

The thermal forces do not resistance to the machine forces.