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Codal Provisions for Design of Machine Foundations - A Review
Conference Paper · November 2014
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Malaviya National Institute of Technology Jaipur
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Indian Institute of Technology Roorkee
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Kathmandu, Nepal
November 20-21, 2014
International Symposium
Geohazards: Science, Engineering and Management
Paper No. EQ-17
Codal Provisions for Design of Machine Foundations – A Review
Bharathi M1†, Dhiraj Raj1, Dr. R.N. Dubey2
Research Scholar, Department of Earthquake Engg., Indian Institute of Technology Roorkee, India
2
Assistant Professor, Department of Earthquake Engg., Indian Institute of Technology Roorkee, India
†
Corresponding Author, Email: bharathi.iitr@gmail.com
1
Key words
Machine foundation,
Code, Design,
Recommendations
1.
Abstract
Machine foundations are of prior importance in almost all types of industries, as
these are subjected to dynamic loads generated by rotating equipmentsmounted
on them. Hence, these should be designed in such a waythat they do not cause
any inconvenience during operation. Machine foundations are analyzed and
designed based on the machine specifications and soil parameters
available.Theprovisions for the design of machine foundations vary among
codes/standards of different countries. All the codes/standardsprovide the
guidelines forthe design of the foundation and also specify the permissible limit
for displacements to ensure proper functioning of the system. An attempt is
made to review the codes/standards on machine foundations that are available
for practicing in differentparts of the world. The codes/standards considered for
this study includes ACI 351 3R 04 (America), CP 2012 (British), DIN 4024
(German), SAES Q 007 (Saudi Aramco) and IS 2974 (Indian).
Machine foundations
Due to tremendous increase in both large and small scale industries, all over the world, the
importance of machine foundation also increases over the time. Engineers fromdifferent
backgrounds are engaged in the analysis, design, construction, maintenance and repair of
machine foundations. Hence, it is important that the operator, engineers involved from different
specialization and equipment supplier should collaborate during the design process to make the
system more efficient and convenient.
2.
Considered Codes/standards on Machine Foundations
In this paper, codes/standards from five different countries are selected for extensive study. The
different types of machines and foundations, design criteria, design methods and construction
considerations are elaborated in [1]. Technical terms, materials & methods, design
considerations for machine foundations and work on site have been discussed by [2]. [3]
Describes the flexible structures that support machines with rotating elements, whereas[4]
explains about rigid structures that support machines with periodic excitations. Both [3,
4]discuss about the basic concepts involved, materials, loads, design and reinforcement
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Kathmandu, Nepal
November 20-21, 2014
International Symposium
Geohazards: Science, Engineering and Management
detailing.Discussion about the basic definitions, forces, loads, design and drawing of machine
foundation system is available in [10].
The Indian Standardsconsists of five parts which consists of foundation for reciprocating
type machines [5],foundations for impact type machines (hammer foundations) [6],foundations
for rotary type machines (medium and high frequency)[7], foundations for rotary type machines
of low frequency[8], and foundations for impact type machines other than hammer (forging and
stamping press, pig breaker, elevator and hoist towers) [9]. An overview of all the considered
codes/standards is presented in the next part.
3.
Overview
All the considered codes/standardsdiscuss the basic terminologies involved in the analysis and
design of machine foundations. The dynamic soil properties used for the design are discussed
along with the test methods in [1, 2, 10]. The considered loads and their combinations for
analysis are discussed in [1, 10]. Both static and dynamic analysis procedures are elaborated in
[1, 3]. Mathematical model of the machine foundation system for simplified analysis with a set
of assumptions are described in [3, 6]. A special consideration to steel foundation is given by
both [3, 10]. All the considered codes/standards have depicted the details of reinforcement in
the foundation for better understanding during construction. Design of block and pile
foundation with anti-vibration mounting, workmanship and responsibilities of civil engineering
contractor, testing and measurement prior to initial running to ensure proper functioning are
special provisions by [2].
4. Design Recommendations
The design recommendations by all the considered codes/standards are presented in the form of
tables as presented in Table 1. Among them, the Indian Standards have given their
recommendations for the analysis and design of machine foundations based on the type of
machine to be mounted on the foundation. Hence, the recommendations by the Indian
Standards are represented separately in Table 2.
The recommendations for the analysis and design of both foundation block and pile
foundation have been discussed. Apart from that, the important parameters viz., eccentricity,
frequency ratio and limiting amplitude have been compared for the considered
codes/standards.Both [3,10] are silent about the recommendations for pile foundations
supporting machines; [3] does not specify any eccentricity and limiting amplitude; and [1] is
silent regarding frequency ratio.
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Kathmandu, Nepal
November 20-21, 2014
International Symposium
Geohazards: Science, Engineering and Management
Table 1: Recommendations by Considered Codes/Standards other than Indian Standards
Description
2.
ACI 351 [1]
Generally the
surface area of
the foundation is
provided by the
manufacturer of
the machine
CP 2012 [2]
 Width of foundation ≥ the
distance from center of
crank shaft to the bottom of
foundation to ensure the
stability against overturning.
 The proportion of the
foundation block should be
such as to ensure stability
against rocking.
 Mass of foundation = 3 to 5
* Mass of the plant
It is suggested
that the block,
combined block,
table top with or
without isolators,
spring mounted
blocks should be
supported on
piles in case of
soft ground
conditions where
low allowable
contact pressure
and excessive
settlements are
obtained in case
of mat
foundation.
 For, axial and
centrifugal
compressors,
with operating
speed > 25,000
rpm, eccentricity
of 250 nm.
 For compressors
at lower speeds,
the maximum
allowable
eccentricity is
dependent on
operating speed.
 The code specifies
circumstances where pile
foundation is required.
 Pile cap thickness ≥ max
(0.6, 1/10 of width)
 The mass of soil
participating with a
foundation supported on end
bearing piles may be
assumed to be the same as
for a raft foundation.
 The interaction of closely
spaced friction piles should
be considered. This
interaction will not be same
as that under static loading.
Foundation
block
Pile
foundation
Eccentricity
 Plan geometric center of
foundation is within 5% of
center of mass.
 The CG of machine and
foundation system should if
possible be below the top of
the foundation block.
DIN 4024 [3]
 Discussion is available on
various foundation loads,
but not on the geometry.
 For simplified vertical
vibration, the effect of the
ground and mass of the
foundation may be
neglected for conditions
stated below:
Lowest natural
frequency in
Limit
case of
Foundation
≥ 0.80
(rigid) and
fs
machine on
spring support
Entire system
≥ 0.80
( rigid) on
fs 3.
flexible ground
Foundation as
≥ 0.75
rigid
ff
where, fs is the lowest
service frequency
ff is frequency of rigid
foundation on flexible
ground
NA
SAES Q 007 [10]
 Thickness of the foundation ≥ 0.6+ (L/30) in
meter, where L is the length of the
foundation.
 Depth of foundation slabs ≥ 1/10 of length of
slab.
 The foundation must have sufficient width to
prevent rocking and adequate depth to permit
properly embedded anchor bolts.
 For < 500 HP
Foundation weight ≥ 3  Machinery weight
 For < 200 HP
Foundation weight ≥ 5  Total machinery
weight
 For reciprocating machines, a minimum of
50% of the block thickness should be
embedded in soil.
NA
The horizontal eccentricity, between the CG of
the machine foundation system and centroid of
soil contact area ≤ 0.05  width or length of
the foundation.
NA
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Kathmandu, Nepal
November 20-21, 2014
International Symposium
Geohazards: Science, Engineering and Management
Table , Continued…
Description
ACI 351 [1]
Frequency
Ratio
NA
Limiting
amplitude
The dynamic
force amplitude is
a function of
rotating mass,
mass eccentricity,
operating
frequency and
service factor.
Only discussions
are available on
important
parameters
involved since
this is a
committee report.
Others
CP 2012 [2]
 Important installations:
Frequency ratio ≤ 0.5 or ≥ 2
 For less importance
installations:
Frequency ratio ≤ 0.6 or ≥
1.5
 When machine is connected
to the foundation by means
of low frequency resilient
anti vibration mountings the
frequency ratio > 3.
To avoid
damage to
DIN 4024 [3]
 Further analysis may be
dispensed with, if both the
following conditions are
satisfied.
 First order frequency
Lowest natural frequency
≤ 0.80fs or 1.25 fs
 Higher order frequency
Natural frequency ≤ 0.90
fs or ≥ 1.10fs
If manufacturer’s vibration criterion is not
available 0.12 and 0.15 inch per second for
centrifugal and reciprocating machines shall be
considered as limiting velocity.
Limit
Specified by
manufacturer
A chart is
Person
proposed
Low speed
Settlement
machines
200µm.
For f < 20Hz
its 200µm.
For f > 20Hz
Building
a chart is
proposed. f =
frequency
Excite the block to same
mode of vibration as
expected from operating
machinery. The vibrations
measured by transducers
with linear response over the
range 2 to 200 Hz. The
accuracy of transducers
should be better than 10%
and they should respond to a
uniaxial motion with not
more than 10% cross
sensitivity.
SAES Q 007 [10]
 For high tuned system:
Frequency ratio < 0.7
 For low tuned system:
Frequency ratio > 1.3
Machinery
NA
Damping factor of the
entire system (machine
plus foundation) may be
assumed to be 0.02 for both
RC and steel structure
where precise information
is not available.
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 For fatigue, the dynamic loads shall be
increased by a factor of 1.5.
 Any structural component not subjected to
dynamic forces shall be designed for a quasistatic load of 50% of dead weight of the
component in any direction in addition to the
static design loads.
 Transmissibility of amplitudes shall be
limited to 20% between adjacent foundations.
 For high or low tuned foundations the soil
bearing pressures shall not exceed 50% or
75% of the allowable bearing pressures
permitted for static loads.
 For a system with continuous support, the
stiffness of the supporting members of the
steel plate will have 3 times the stiffness of
the base plate.
Kathmandu, Nepal
November 20-21, 2014
International Symposium
Geohazards: Science, Engineering and Management
Table 2, Recommendations by Indian Standards
Description
IS 2974 [5]
 Empirical rules (related to mass,
eccentricity and stability) are suggested
for deciding the geometry of foundation
block.
 Mass of foundation >> Mass of machine
Foundation
block
IS 2974 [6, 9]
4.
7.
10.
13.
16.
17.
Pile
foundation
Eccentricity
Frequency
Ratio
 The eccentricity < 5% of the base
dimension of block.
 CG of combined system should lie below
the top of the foundation block.
1.5 <
Machinery
Up to 1.0
1.00
1.0 to 2.0
1.25
2.0 to 4.0
1.75
4.0 to 6.0
2.25
Dimension
Clear span
to depth
Depth to
width
 Base Mat
Over 6.0
Ratio
5.
Range
6.
Mf/ 8.
Mt
60 9.
Mf/ 11.
Mt
80 to
12.
100
Mf/ 14.
Mt
10015.
to
120
2.50
Soil Type
General
stiff clay or
compact sandy
Moderately
firm to soft
clays and
medium dense
to loose sand
Where, Mf = Mass of the foundation
Mt= Mass of the tup
<0.67
Girder
supporting
Turbine
Girder
supporting
Generator
2 to 3
2.5 to 3.5
1 to 3
1 to 1.5
≥2
 Thickness of base raft > 0.07 L4/3, L is the
average of two adjacent clear span length.
(only for raft)
18.
A chart is proposed
Low speed machines 200µm.
For f < 20Hz its 200µm.
Building
For f > 20Hz a chart is
proposed. f = frequency
 In case of important structures present
near the foundation, the amplitude of the
foundation should be adjusted so that the
velocity of the vibrations at the structure
does not exceed 0.3cm/s.
 If the soil at site is subjected to excessive
settlement then a semi-buoyant or fully
buoyant foundation may be provided.
Fatigue factor of 3 is used for design to take
care of reduction in strength of concrete and
steel due to repeated loading.
Part
Foundation
Anvil
Amplitude (mm)
1
1.5
2
1
2
3-4
Load intensity on the soil below the
foundation ≤ 80% of the allowable
bearing pressure of the soil or
material.
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Under unavoidable circumstance, a
maximum eccentricity of 3% base
dimension may be allowed.
1.25<
(Impact machine other than hammer)
Tup mass
<1
1-3
>3
(tons)
Limit
Specified by manufacturer
CG of anvil and the foundation block,
resultant force in the elastic pad and
supported foundation should coincide
with the line of fall of hammer tup as
far as practically possible.
1.43 <
<0.4
Person
Settlement
Others
Mass of tup
(Tons)
 Pile caps thickness > 60cm
 Pile Soil Stiffness factors is obtained by in situ test on single pile with free head condition. In actual practice the pile is used in a
group with pile heads largely restrained by the pile cap. If it is not possible to conduct in-situ tests, computative method of
estimation can be adopted.
 The CG of the system (foundation and machine) < 5% length of the foundation with respect to the CG of the pile group. (Applicable
for reciprocating machine only)
To avoid
damage to
Limiting
amplitude
IS 2974 [7, 8]
Thickness of
foundation block
(m)
<0.83
 Amplitudes ≤ 0.20 mm in lateral
directions.
 Amplitude ≤ 0.26 mm (several
foundations are erected on a common mat)
Fatigue factor of 2 is used for dynamic
analysis.
Kathmandu, Nepal
November 20-21, 2014
5.
International Symposium
Geohazards: Science, Engineering and Management
Conclusions
An extensive study about theconsidered codes/standards on machine foundation is carried
outand a common observation is that the procedure for the design of machine foundation
supported on piles is not available in detail. Some of the considered codes/standards suggest
that the dynamic analysis procedure of piles can be adopted for the analysis and design of pile
foundations supporting machines. This is due to fact that the design of pile foundations
supporting the machines depends on several non-dimensional and interaction parameters.
Acknowledgment
The authors are grateful to IIT Roorkee for providing the facilities for this investigation.
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
ACI: 351-3R-2004, "Foundations for Dynamic Equipment", American Concrete
Institute.
CP: 2012 (Part I)-1974, "Code of practice for Foundations for Machinery",
BSI,London.
DIN: 4024 (Part I)-1988,"Machine Foundations – Flexible Structures that Support
Machines with Rotating Elements", German Standards.
DIN: 4024 (Part II)-1988,"Machine Foundations – Rigid Structures that Support
Machines with Periodic Excitation", German Standards.
IS: 2974 (Part I)-1982, “Code of Practice for Design and Construction of Machine
Foundations - Foundation for Reciprocating Type Machines”, BIS New Delhi, India.
IS: 2974 (Part II)-1980, “Code of Practice for Design and Construction of Machine
Foundations - Foundations for Impact Type Machines (Hammer Foundations)”, BIS
New Delhi, India.
IS: 2974 (Part III)-1992, “Code of Practice for Design and Construction of Machine
Foundations - Foundation for Rotary Type Machines (Medium and High
Frequency)”, BISNew Delhi, India.
IS: 2974 (Part IV)-1979, “Code of Practice for Design and Construction of Machine
Foundations - Foundation for Rotary Type Machines of Low Frequency”, BISNew
Delhi, India.
IS: 2974 (Part V)-1987, “Code of Practice for Design and Construction of Machine
Foundations - Foundations for Impact Machines other than Hammers”, BISNew
Delhi, India.
SAES: Q–007-2003, "Foundations and Supporting Structures for Heavy Machinery",
Onshore Structures, Saudi Arabia.
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