Machine Foundation

The design requirement for machine foundation is not the safety of the foundation alone, but Satisfactory Machine Performance too, with the main thrust directed towards minimization of machine down time i.e., machine non-performance due to unacceptable level of dynamic interaction between machine and the foundation. Inadequately designed and constructed foundations may lead to failures and shutdowns, and the shutdown cost may exceed many times the cost of the capital investment required for properly designed and built foundations. The satisfactory machine performance is witnessed only after the machine is erected on the designed foundation and commissioned for its operation.

The performance, safety and stability of machines depend largely on their design, manufacturing, and interaction with environment. Hence, the role of the foundation designer is to target the desired machine performance through its design and for this, the designer must have sound knowledge of Structural Dynamics involving interaction amongst Dynamic Soil Parameters, Dynamic Foundation Parameters as well as Dynamic Machine Parameters. However, no importance was attached to vibration testing of the foundation, that in turn resulted in frequent performance problems of the machine/ foundation.

The cost of machine foundation is but a small fraction of that of the equipment and inadequately constructed foundations may result in failures and shutdowns exceeding many times the cost of the capital investment required for properly designed and built foundations. With the current technological advancements in design and manufacturing, machines of higher ratings with stringent tolerances, with no room for failure, have been developed, which in turn demand higher performance reliability. It indirectly warrants that foundation for each, and every machine must undergo detailed vibration analysis to ensure satisfactory machine performance. Knowing well that the “Proof of pudding is in eating only” the satisfactory machine performance is witnessed only after the machine is erected on the designed foundation and commissioned for its operation. Thus, vibration tests on the foundation become a necessary performance requirement.

Many scientists have contributed to the field of machine foundation laying great emphasis on vibration response of machine foundation system and contributed greatly to the practical and theoretical development of the subject. Study of vibration problems associated with machine foundations necessitated investigations into dynamic response analysis of machine foundation system.

With the current technological advancements in design and manufacturing, machines of higher ratings with stringent tolerances, with no room for failure, have been developed, which in turn demand higher performance reliability. It indirectly warrants that foundation for each, and every machine must undergo detailed vibration analysis to ensure satisfactory machine performance. Knowing well that the “Proof of pudding is in eating only” the satisfactory machine performance is witnessed only after the machine is erected on the designed foundation and commissioned for its operation. Thus, vibration tests on the foundation become a necessary performance requirement.

This necessitated investigations into dynamic response analysis of machine foundation system. Observations from the Failure Analysis Investigations and Review of Machine Foundations Behaviour conducted on various types of machines, suggest need for improvement in the design of foundations for better machine performance and better understanding of Machine foundation interaction.

I have been associated with Design, Testing, and Troubleshooting of Machine Foundations for over last five decades. Though, in the initial years of my professional career, I was associated only with the design of machine foundations, later I got into troubleshooting and the field testing as well. I conducted Field Vibration Testing on variety of machines and their foundations. I had the privilege of testing some of the foundations designed by me. After conducting vibration tests on machines and foundations, I realized that there exist wide variations between the response values computed at design stage and those obtained from Field vibration tests. The comparison of design results with test results was an eye opener for me and provided the insight into the gaps that a designer must consider while designing the foundation for a dynamic machine.

The Observations from the Failure Analysis Investigations and Review of Machine Foundations Behaviour conducted on various types of machines for various industrial projects viz. Petrochemicals, Refineries, Power plants etc. over the last few decades, suggest need for improvement in the design of foundations for better performance of machines. The outcome suggests the need for more comprehensive evaluation of Site Soil Data, better understanding of Machine Data and improvement in the Design Philosophy. These in turn call for improvement in:

The work done by me, has been presented in various technical forums in India as well as globally. The rich experience gained during the testing and troubleshooting, has been compiled, consolidated, and translated into a handbook "Foundations for Industrial Machines - Handbook for Practising Engineers". Its 1st edition was published in 2008 & 2nd edition was brought out in 2011. The book covers basic fundamentals necessary for understanding and evaluating dynamic response of machine foundation system. Stress is laid on detailed dynamic analysis for evaluating the response. Use of commercially available Finite Element packages are recommended for analysis and design of the foundation.

BIS code available for machine foundation design is IS-2974. It contains 5 parts in order to cover foundation design of different machines. These codes are about 20 years old, and the methodology present is not able to address the performance requirements of new machines requiring stringent vibration tolerances to ensure satisfactory machine performance.

BIS in 2009 took up the revision of IS 2974 (Part1 through Part 5), and I have been entrusted with the responsibility of Convenor to take up the desired revision of this code. The effort is continuing for last 12 years or so. All the revisions are in draft stage nearly ready for final printing.

I have been deeply associated with Structural Dynamics for past about 54 years and have worked on seismic qualification of variety of equipment and industrial structures used in the industry. Typical work areas are:

About 4 to 5 decades ago, no industry attached requisite importance to seismic safety of equipment and industrial structures except nuclear and some petrochemical facilities. At that time, there were no codes that addressed earthquake resistant design needs of Industry viz. Industrial Structures, Equipment and Machinery. This scenario was common globe over. Most of the codes, globe over, covered Earthquake Resistant Design of Buildings adequately with a little or no mention of applicability of these provisions for Industrial Systems. Whereas the analytical procedures used for seismic qualification of building/ structures can be said to have been established and validated, such validations were practically missing for equipment and industrial structures. It emerged that Importance Factor, Load combination procedures, Formulae for computing fundamental frequency/time period are some of the areas that need to be addressed distinctly for industrial systems.

Lack of concern for seismic safety of industrial systems, seems to be on account of (a) lack of awareness about the risk of earthquake damage, (b) lack of availability of norms and guidelines to cater to this aspect, (c) absence of any regulatory authority and most important is (d) infrequent visits of earthquakes to industrial set-up locations. It required understanding seismic qualification requirements, method of qualification, e.g., Testing/Analytical, their merits/demerits; limitations etc. for industrial systems and identify the grey areas that need immediate attention.

Seismic safety requirements of industrial systems gained importance during early seventies with the setting up of a Narora Atomic Power Plant (NAPP) located in high seismic belt in India. It demanded development of required norms to ensure safety of the plant.

Needless to mention that Seismic Qualification of all the equipment on the primary side (BHEL supply) was conducted by me. Designs done by me were cleared by DAE and its foreign consultants. Thereafter there was no looking back, and I was entrusted with the seismic qualification tasks of other Nuclear Power plants (Kakarapar & Kaiga).

Whereas seismic safety of all the structures was handled directly by Department of Atomic Energy (DAE), the responsibility of the seismic safety of equipment and machinery was entrusted to the manufacturer. I got associated with this task in 1975 on behalf of Bharat Heavy Electricals Ltd. (BHEL) who were the suppliers of Nuclear Steam Generator.

To understand the global scenario with regard to Seismic Qualification of Industrial Systems, I organized a "Symposium on Earthquake Effects on Plant and Equipment", at Hyderabad, India, in 1984. This symposium was with global participation. The outcome of the symposium was to firm up development of guidelines to deal with seismic safety of Industrial Plants and Equipment.

It was at this time that I was given the responsibility of developing design methods for seismic safety of Industrial systems, by Dr. Jai Krishna, the Father of Earthquake Engineering, in India. Need was felt by Dr Jai Krishna to split the existing code IS -1893 into various parts, each dealing with seismic safety of one or other aspect of the engineering structures and systems in India.

With this decision, I was made the convenor (in 1990 or so) responsible for developing a code for "Earthquake Resistant Design of Industrial Structures" i.e., IS 1893 - Part 4. All leading industries joined this endeavor. Another symposiums "Symposium on Earthquake Effects on Structures, Plant and Machinery" at New Delhi, India, was organized by me in 1996 to get more contribution from the wide cross section of engineering community.

After deliberations for about 15 years with various engineering industries and academic institutions, the first edition of IS 1893 - Part 4 "Earthquake Resistant Design of Industrial Structures including Stack Like Structures", was brought out by BIS in 2005. First revision of this code was brought out in 2015. For last about 5 years, the code was taken up for its next revision which is likely to be out in 2022.

Besides, I have organized many training programs from 2008 onwards on "Earthquake Resistant Designs of Industrial Systems", for practising engineers. It is good to note that many academic institutions, over the years, have also shown interest in this subject area and have conducted training from time to time.

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Machine Foundation and Structural Dynamics