ACI 351.3R-04 Foundations For Dynamic Equipment.pdf

ACI 351.3R-04 Foundations for Dynamic Equipment

Dynamic equipment is any machinery that produces or receives dynamic forces or motions, such as rotating, reciprocating, impact, or impulsive machines. Examples of dynamic equipment include turbines, compressors, pumps, generators, engines, hammers, presses, and crushers. The design of foundations for dynamic equipment requires special considerations to ensure satisfactory performance and safety. The American Concrete Institute (ACI) has published a report on this topic, titled "Foundations for Dynamic Equipment" (ACI 351.3R-04), which presents the various design criteria and methods and procedures of analysis, design, and construction applied to dynamic equipment foundations. This article will provide a brief overview of the main contents and recommendations of this report.

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Foundation and machine types

The report classifies dynamic equipment into three main types: rotating, reciprocating, and impact or impulsive machines. Each type of machine has different characteristics and effects on the foundation, such as frequency, amplitude, direction, and duration of the dynamic forces or motions. The report also describes the common types of foundations used for dynamic equipment, such as block foundations, frame or pedestal foundations, pile foundations, and mat foundations. The selection of the foundation type depends on several factors, such as the size and weight of the machine, the soil conditions, the vibration performance criteria, and the economic considerations.

Design criteria

The report provides an overview of the design criteria for dynamic equipment foundations, which include the following aspects: foundation and equipment loads, dynamic soil properties, vibration performance criteria, concrete performance criteria, and performance criteria for machine-mounting systems. The report also provides a method for estimating the inertia forces from multi-cylinder machines.

• Foundation and equipment loads: The design loads for dynamic equipment foundations consist of static loads and dynamic loads. Static loads include the weight of the machine and its accessories, the weight of the foundation and its components, and any other permanent or transient loads. Dynamic loads include the forces or motions generated by the operation of the machine or transmitted from external sources. The report discusses how to determine the magnitude, frequency, direction, and location of the dynamic loads for different types of machines.

• Dynamic soil properties: The dynamic behavior of the soil supporting the foundation is influenced by its density, stiffness, damping, and nonlinear characteristics. The report explains how to obtain the dynamic soil properties from field tests or empirical correlations. The report also discusses how to account for the effects of soil-structure interaction on the foundation response.

• Vibration performance criteria: The vibration performance criteria are the limits or specifications that define the acceptable level of vibration for the foundation and the machine. The report presents various criteria based on displacement, velocity, acceleration, frequency, or amplitude ratios. The report also discusses how to select or establish appropriate criteria for different types of machines and applications.

• Concrete performance criteria: The concrete performance criteria are the requirements that ensure the durability and strength of the concrete foundation under static and dynamic loading conditions. The report provides recommendations on concrete materials, mix design, curing, reinforcement detailing, cracking control, and quality control.

• Performance criteria for machine-mounting systems: The machine-mounting system is the interface between the machine and the foundation that transfers the loads and motions between them. The report describes various types of machine-mounting systems, such as rigid mounts, resilient mounts (such as springs or rubber pads), sliding mounts (such as steel plates or Teflon pads), and isolation systems (such as air springs or viscous dampers). The report also provides guidance on how to select or design suitable machine-mounting systems based on their stiffness, damping, alignment, stability, and isolation characteristics.

Design methods and materials

The report presents an overview of the design methods and materials for dynamic equipment foundations. The design methods include analytical methods (such as lumped-mass models or finite-element models), experimental methods (such as scale models or field tests), and empirical methods (such as charts or formulas). The design materials include concrete (normal-weight or lightweight), steel (reinforcing bars or structural shapes), grout (cementitious or epoxy), and isolation materials (such as rubber, springs, or dampers). The report also provides guidance on how to use these methods and materials to achieve the desired vibration performance and structural integrity of the foundation.

Repairing and upgrading foundations

The report discusses the common causes and symptoms of foundation problems, such as excessive vibration, cracking, settlement, misalignment, or corrosion. The report also provides recommendations on how to diagnose, repair, and upgrade existing foundations for dynamic equipment. The repair and upgrade techniques include strengthening, stiffening, damping, isolating, leveling, grouting, anchoring, or replacing the foundation or its components.

Conclusion

The report "Foundations for Dynamic Equipment" (ACI 351.3R-04) is a valuable resource for industry practitioners who are involved in the design, construction, repair, or upgrade of concrete foundations for dynamic equipment. The report covers the various aspects and challenges of this topic, such as foundation and machine types, design criteria, design methods and materials, and repairing and upgrading foundations. The report provides practical guidance and recommendations based on the current state of knowledge and practice in this field.

References:

• ACI Committee 351. Foundations for Dynamic Equipment. ACI 351.3R-04. American Concrete Institute, Farmington Hills, MI, 2004.