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Practical Practical

Machine Machine

Foundation Foundation

Design Design

(1Hr Webinar)(1Hr Webinar)

Presented by Dr. Gamal Abdelaziz P.Eng

Sponsored by SAGA Engineering

September 25, 2014 – 12pm MDTgic‐edu.com

AgendaAgenda

• Introductions• Types of loads and machine foundations• Dynamic soil properties needed for the

l ianalysis• Dynamic Design criteria• Sample design foundations‐ case studies• Closing

*General questions will be discuss ifGeneral questions will be discuss if time allows. Administrative questions are welcome but will be posted in a new FAQ section on the GIC website.

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Introductions

Dr. Gamal Abdelaziz, P.Eng, MSc. has a Ph.D. in Geotechnical Engineering from Concordia University, Montreal, Canada. Dr. Abdelaziz has over 30 years of experience in geotechnical and structural engineeringexperience in geotechnical and structural engineering, foundation design, teaching, research and consulting in Canada and overseas.

EoR for Stony Plain ring road, Calgary, AB.

Currently he is a senior geotechnical engineer with SAGA Engineering, Edmonton, Alberta.

S G i i

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SAGAengineering.ca

PRACTICAL MACHINE PRACTICAL MACHINE FOUNDATION DESIGN FOUNDATION DESIGN

Dr. Gamal Abdelaziz, Ph.D., Dr. Gamal Abdelaziz, Ph.D., P.Eng.P.Eng.

Senior Geotechnical EngineerSenior Geotechnical Engineer

SAGA EngineeringSAGA Engineering

Edmonton, AlbertaEdmonton, Alberta

Former Visiting Professor, Ryerson Former Visiting Professor, Ryerson University, Adjunct Professor, University of University, Adjunct Professor, University of

Western OntarioWestern Ontario

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Dr. Gamal Abdelaziz, Ph.D., P.Eng.Dr. Gamal Abdelaziz, Ph.D., P.Eng.Managing DirectorManaging Director




SAGA EngineeringSAGA Engineering

Edmonton, AlbertaEdmonton, Alberta

Former Visiting Professor, Ryerson University, Adjunct Professor, Former Visiting Professor, Ryerson University, Adjunct Professor, University of Western OntarioUniversity of Western Ontario

• The process in which the response of the soil influences the motion of the

SOIL STRUCTURE SOIL STRUCTURE INTERACTION (SSI) DefinitionINTERACTION (SSI) Definition

the soil influences the motion of the structure and the motion of the structure influences the response of the soil is termed as SSI.

• In this case neither the structural

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displacements nor the ground displacements are independent from each other.

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• Traditional Structural Engineering

SOIL STRUCTURE INTERACTION SOIL STRUCTURE INTERACTION (SSI) Definition(SSI) Definition

methods disregard SSI effects, which is acceptable only for Light structures on relatively stiff soil (low rise structures and simple rigid

t i i ll )


retaining walls).

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• SSI effects become prominent and must be regarded for structures where P-δ


be regarded for structures where P-δeffects play a significant role, structures with massive or deep seated foundations, slender tall structures and structures supported on a very soft soils with

h l it l th 100


average shear velocity less than 100 m/s.[Euro Code 8].

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• Modern Seismic Design Codes such as Standard Specifications for Concrete


Standard Specifications for Concrete Structures: Seismic Performance Verification JSCE 2005 (Japan Society of Civil Engineers) highlight that the response analysis should take into account the whole


structural system (superstructure + foundation + soil ).

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• SSI EFFECTS

Alt th N t l F f th St t• Alter the Natural Frequency of the Structure Considering soil-structure interaction makes a structure more

flexible and thus increases the natural period of the structureas compared to the corresponding rigidly supported structure.

• Add Damping Considering the SSI effect increases the effective damping


Considering the SSI effect increases the effective dampingratio of the system

(Superstructure + Foundation + Soil ).

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SSI SSI –– PROBLEM DEFINITIONPROBLEM DEFINITION

Machine FoundationMachine Foundation Seismic ExcitationSeismic Excitation


Inertial Interaction

Inertial forces in structure are transmitted to flexible soil

Kinematic Interaction

Stiffer foundation can not conform to the

distortions of soil

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General Requirements of Machine Foundations General Requirements of Machine Foundations and and Design CriteriaDesign Criteria

((RichartRichart, Hall and Woods, 1970; , Hall and Woods, 1970; SrinivasuluSrinivasulu and and VaidyanathanVaidyanathan, 1976; , 1976; KameswaraKameswaraRaoRao, 1998), 1998)

• 1. Settlements should be within permissible limits.

• 2. Foundation block should be structurally yadequate to carry the loads.

• 3. The combined center of gravity (CG) of machine and foundation and the center of contact area (with the soil) should lie on the same vertical line as far as possible.


General Requirements of Machine Foundations General Requirements of Machine Foundations and and Design CriteriaDesign Criteria

((RichartRichart, Hall and Woods, 1970; , Hall and Woods, 1970; SrinivasuluSrinivasulu and and VaidyanathanVaidyanathan, 1976; , 1976; KameswaraKameswaraRaoRao, 1998), 1998)

• 4. Resonance should not occur. Accordingly, wherever possible, the operating frequency should be lower than the natural frequency of the system, n, that is

n ≤ should not be less than 0.5

• If the operating frequency happens to be more than the natural frequency, then


q y,

n ≥ should be more than 2.0

• /n ≤ 0.5 or /n ≥ 2

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• Periodic motion: A motion which repeats itself after equal intervals of time.

DEFINITIONSDEFINITIONS

• Time period: Time taken to complete one cycle.

• Frequency: Number of cycles per unit time.

• Amplitude: The maximum displacement of a vibrating body from its equilibrium position.


• Natural frequency: When no external force acting on the system after giving it an initial displacement, the body vibrates. These vibrations are called free vibrations and their frequency as natural


vibrations are called free vibrations and their frequency as natural frequency. It is expressed in rad/sec or Hertz.

• Fundamental Mode of Vibration: The fundamental mode of vibration of a system is the mode having the lowest natural frequency.


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Simple Harmonic Motion:

• The motion of a body to and from about a fixed point is called simple harmonic motion


harmonic motion.

• The motion is periodic and its acceleration is always directed towards the mean position and is proportional to its distance from mean position.

• The motion of a simple pendulum is simple harmonic in nature.

• Let a body having simple harmonic motion is represented by the equation


Damping: It is the resistance to the motion of a


It is the resistance to the motion of a vibrating body.

The vibrations associated with this resistance are known as damped vibrations.


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Resonance: When the frequency of external excitation is

l h l f f ib i


equal to the natural frequency of a vibrating body, the amplitude of vibration becomes excessively large.

This concept is known as resonance.

Mechanical systems: The systems consisting of mass stiffness and


The systems consisting of mass, stiffness and damping are known as mechanical systems.

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Continuous and Discrete Systems: Most of the mechanical systems include


yelastic members which have infinite number of degree of freedom.

Such systems are called continuous systems.

Continuous systems are also known as


ydistributed systems.

Cantilever, simply supported beam etc. are the examples of such systems.

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DEGREE OF FREEDOM: • The minimum number of independent coordinates required to specify the motion

of a system at any instant is known as degrees of freedom of the system.y y g y

• In general, it is equal to the number of independent displacements that are possible.

• This number varies from zero to infinity.

• The one, two and three degrees of freedom systems are shown in figure 2.

In single degree of freedom there is only oneindependent coordinate x1 to specify the


independent coordinate x1 to specify theconfiguration as shown in figure 2 (a). Similarly, thereare two (x1, X2). and three coordinates (x1, X2 andx3) for two and three degrees of freedom systems asshown in figure 2 (b) and 2 (c)

Foundations for Foundations for Vibrating EquipmentVibrating Equipment

• Heavy machinery with reciprocating, impacting, or rotating masses requires a support system that can resist dynamic forces and the resulting vibrations.

• Two major impacts: its support system, and any operating personnel subjected to them.


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• Some of machine foundation design procedures and criteria are not covered in building codes gand national standards.

• Some firms and individuals have developed their own standards and specifications as a result of research and development activities, field studies, or many years of successful engineering or construction practices.


• Unfortunately, most of these standards are not available to many practitioners.

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Possible Movement for Block Possible Movement for Block foundation:foundation:

ZY

X

Y

θφ


X

ψ

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General General Requirements of Requirements of Machine Machine Foundations and Foundations and Design CriteriaDesign Criteria

• Some of the important requirements of a machine-foundation-soil system (MFS) can be listed as follows (Ri h t H ll d W d 1970 S i i l d V id th 1976 K R(Richart, Hall and Woods, 1970; Srinivasulu and Vaidyanathan, 1976; Kameswara Rao,

1998):

1. Settlements should be within permissible limits.

2. Foundation block should be structurally adequate to carry the loads.

3. The combined center of gravity (CG) of machine and


foundation and the center of contact area (with the soil) should lie on the same vertical line as far as possible.

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General General Requirements of Requirements of Machine Machine Foundations and Foundations and Design CriteriaDesign Criteria

4. Resonance should not occur.

• Accordingly, wherever possible, the operating f h ld b l th th t lfrequency should be lower than the natural frequency of the system, n that is

/n should be less than 0.5

• If the operating frequency happens to be more than the natural frequency, then

• /n should be more than 2.0


n

• Thus the design criterion on frequency can be written as

• /n ≤ 0.5 or /n ≥ 2

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− The amplitudes of displacement or velocity or acceleration of the MFS should be within permissible limits.

− These are generally prescribed by the machine− These are generally prescribed by the machine manufacturers.

− Some general design criteria (IS: 2974-1966, 1966) are shown in Figures 11.2-11.4.

− Tolerable levels of vibration are related to:

a. human perception


b. maintenance problems and potential damage to machines or instruments

c. potential damage of structural components

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d. avoidance of total failure

e. the dimensions of machine foundations.

• These should conform to operational requirements of the machine in addition to the minimum clearances from the foundation bolts as stipulated by codes (IS:


foundation bolts as stipulated by codes (IS: 2974-1966, 1966) and manufacturers.

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Figure 11.2 Limiting amplitudes for

vertical vibration. (Richart EE /Hall(Richart, EE./Hall, J.R./Woods, R.D., Vibrations of Soils and Foundations,

1st Edition, © 1970, p. 311. Printed and

electronically reproduced by permission of


permission of Pearson Education, Inc., Upper Saddle River, New Jersey.)

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Figure 11.3 Criteria for vibrations of rotating

machinery. (Reproduced from M P Blake "Newfrom M.P. Blake, Newvibration standards for

maintenance," Journal of Hydrocarbon Processing and Petroleum Refiner, vol. 43, no. 1, pp. 11 1-

114, © 1964, with permission from Gulf Publishing Company,

Houston, Texas.)


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Machine Performance ChartMachine Performance Chart

Performance Zonesns

-pl

itud

e -

A=No Faults, NewA=No Faults, NewB=Minor FaultsB=Minor Faults, , Good ConditionGood ConditionC = Faulty, Correct C = Faulty, Correct In 10 Days To In 10 Days To Save $$Save $$D = Failure Is D = Failure Is N C t I 2N C t I 2m

plit

ude

of v

ibra

tion

n be

arin

g. S

ingl

e am

p


Near, Correct In 2 Near, Correct In 2 DaysDaysE = Stop NowE = Stop Now

Hor

izon

tal a

mm

easu

red

on

Figure 11.4 Response spectra for vibration

limits (Richart EE /Halllimits. (Richart, EE./Hall, J.R.lWoods, R.D.,

Vibrations ofSoils and Foundations, 1st Edition, © 1970, p.

316. Printed and electronically

reproduced by


permissionof Pearson Education,

Inc., Upper Saddle River, New Jersey.)

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• As a guideline, the approximate weights of the foundation blocks in terms of multiplesthe foundation blocks in terms of multiples of the weight of the machines being supported can be used as an initial guess and are given in Table 11.1 (Leonards, 1962).



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Types of Machines in Oil and Types of Machines in Oil and Gas IndustryGas Industry

• 1. Centrifugal Machines ( Rotating)


• 2. Reciprocating Machines


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Centrifugal Machine Centrifugal Machine (Rotating)(Rotating)


Fig-3

Reciprocating MachineReciprocating Machine


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Classification of rotating machines Classification of rotating machines based on Frequency/speedbased on Frequency/speed

• Very low speed machines < 100 rpm

• Low speed machines 100 rpm to 500 rpm• Low speed machines 100 rpm to 500 rpm

• Medium Speed machines 500 rpm to 1500 rpm

• Moderately high speed machines 1500 rpm to 3000 rpm


p p

• High speed machines >3000 rpm

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Various Types of Machine Various Types of Machine FoundationsFoundations


1.Block (Concrete) Type 2. Frame ( Concrete or Steel) Type

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1.Block (Concrete)Supported by piles

2. Frame ( Concrete or Steel)supported by Piles

INPUTSINPUTS

• What inputs are needed for foundation design?foundation design?

• The inputs are broadly categorized as

• Project Design basis for Machine foundation


foundation

• Soil Parameters for foundation Design

• Machine vendor inputs

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What inputs are available in What inputs are available in Project Design basis?Project Design basis?

• The following are the major inputs to be extracted from the project design basis:

• Criteria for Dynamic Analysis

• Permissible Amplitudes of Displacements and rotation of the foundation in the absence of Vendor data.

• Grade of Material ( Concrete/Steel ) to be used for


• Grade of Material ( Concrete/Steel ) to be used for the construction of Machine foundation

• Permissible % of bearing pressures for dynamic loading.

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What are the Soil Parameters What are the Soil Parameters required?required?

• Primary parameters

• 1. Dynamic Shear Modulus

• 2. Poisson’s Ratio

• 3. Damping factor


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• Secondary Parameters

• 1. Coefficient of Elastic uniform compression Cz

• 2. Coefficient of Elastic uniform shear Cτ

• 3. Coefficient of Elastic non uniform


compression Cθ

• 4. Coefficient of Elastic non uniform shear Cψ

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How to determine the Soil How to determine the Soil Parameters?Parameters?

• Field Tests :

• Cross Hole Test ( CHT).

• Down hole test (DHT).

• Spectral Analysis of Shear wave ( SASW)


SASW)

• Block Vibration Tests

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• Laboratory tests:

• Resonant Column test

• Cyclical Tri axial Test

• The above test are conducted usually by


The above test are conducted usually by a Geotechnical Contractor and appropriate values are recommended by him in the Geotechnical report

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Cross hole testCross hole test--schematicschematic

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Down hole testDown hole test--SchematicSchematic


Fig-8

Spectral Analysis of Shear Wave Spectral Analysis of Shear Wave --SchematicSchematic


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Block vibration TestBlock vibration Test



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Damping factor Damping factor determinationdetermination--

Forced/Free Vibration Forced/Free Vibration testtest Responsetesttest Response

Curve under Forced Vibration


The damping factor () can now be obtained using the relation


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Machine Vendor InputMachine Vendor Input

• The following input is required from the machine vendor:machine vendor:

• Geometric configuration of the Machine

• Loads from the Machine: Mass of the stationary as well as rotating parts of the machine and load transfer mechanism from


machine and load transfer mechanism from machine to the foundation

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• Critical Machine performance parameters: Critical speeds of rotors balance gradesCritical speeds of rotors, balance grades and acceptable levels of amplitudes of vibration

• Dynamic forces generated by the Machine: forces generated under various operating conditions and their transfer


p gmechanism to the foundation for dynamic response analysis.

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• Additional forces generated under emergency or faulted conditionsemergency or faulted conditions, Test condition, Erection condition & Maintenance condition of the machine, forces due to bearing failure ( if applicable) for strength analysis of the f d ti


foundation.

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Typical Vendor Input (Machine GAD):Typical Vendor Input (Machine GAD):


Fig-12

ANALYSIS & DESIGNANALYSIS & DESIGN

• The Analysis of the Machine foundation is done in two stages:g

• Dynamic Analysis : Includes determination of the natural frequencies of the Machine foundation system and calculation of amplitudes of displacements and rotations of the foundation under dynamic loading.


• Static Analysis: Includes check for strength of the foundation, stability of the foundation and check for soil bearing capacity.

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• The significant aspects of soil properties which influence soil-structure interactions are:

• Energy transfer mechanism- Not quantifiable

• Soil mass participation in vibration of the foundation-Not quantifiable

• Effect of embedment of foundation- Approximately quantifiable

• Applicability of Hooke’s law to soil- To some extent


• Applicability of Hooke s law to soil- To some extent

• Dynamic soil parameters-Approximately quantifiable

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Deformation modes of soilDeformation modes of soil

• Based on above deformable modes of foundation, the following deformablefoundation, the following deformable modes can be anticipated for Soil beneath the block foundation:

• Uniform Compression

• Uniform Shear


• Non Uniform compression

• Non Uniform shear

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• In the context of Machine foundation design a Machine would necessarilydesign, a Machine would necessarily include:

• A drive machine

• A driven machine


A driven machine

• A coupling device

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• A typical data set required for each of the components shown in the previous schematic is:

• For dynamic response analysis of foundation:

• Total mass of machine ( including rotating t )


parts),

• Radius of gyration and its over all centroidlocation.

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For dynamic response For dynamic response analysis of foundation:analysis of foundation:

• Mass of rotating parts of the machine, operating speed, height of the centreoperating speed, height of the centre of the rotor from machine base frame, etc

• Foot print of machine base frame, details of holding down bolts


• Dynamic forces generated by the machine under operating conditions

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For strength design of For strength design of foundation:foundation:

• Static loads from machine

• Equivalent static forces i e dynamic forcesEquivalent static forces i.e. dynamic forces converted to equivalent static forces

• Forces generated under emergency and faulted conditions eg: bearing failure, loss of blade, short circuit etc.

• Forces during erection maintenance and


• Forces during erection, maintenance and test conditions of the machine.

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Parameters for rotary Parameters for rotary (centrifugal) machines:(centrifugal) machines:

• Balancing of rotating machine



• Force Generated due to unbalanced condition

• F= meω2

• The above force is called unbalanced force

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• Unbalanced forces along the shaft with multiple supports

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RotorRotor

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RotorRotor

• In every rotating machine there will be certain amount of unbalance (eccentricity) which is inevitable.

• ISO/ Machine manufacturer has set standards for the allowable eccentricity based on:


• Function of the machine

• Speed of the machine and

• Rotating mass

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• Many rotating machines are balanced to an initial balance quality as per ISO standards.initial balance quality as per ISO standards.

• This is called the balance quality grade.


Fig-19


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• Critical speeds: Correspond to flexural frequencies of the rotorflexural frequencies of the rotor.

• These are supplied by the vendor. High vibration can occur on account of resonance of foundation with critical speeds


foundation with critical speeds

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• Forces due to Emergency conditions:

• Bearing Failure: Grinding halt of machine g gdue to failure of bearings.

• Difficult to quantify and can be taken as an static force equivalent to 3 to 5 times the rotor weight.

• Short circuit force: Furnished by Machine


Short circuit force: Furnished by Machine vendor

• Loss of parts like blade: Furnished by Machine vendor

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Elastic Half SpaceElastic Half Space


Waves Waves


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Waves Waves

Rayleigh, R SurfaceSurface

Shear,SSecondary


Compression, P Primary

Comparing Circular and Comparing Circular and Sinusoidal Motion Sinusoidal Motion


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Simple Harmonic Motion:Simple Harmonic Motion:


11--DOF MassDOF Mass--Spring Systems with Spring Systems with DampingDamping


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UndampedUndamped OscillatorOscillator


Damped OscillatorDamped Oscillator


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Foundation ParametersFoundation Parameters

• Under tuned foundation:

• The vertical vibration frequency is < operating q y p gfrequency of the machine

• Preferred for Medium to High speed Machines

• Over tuned foundation:

• The vertical vibration frequency is > Operating frequency of the machine


frequency of the machine

• Preferred for very low to low speed machines

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Vibration Limits in Machine Vibration Limits in Machine Foundation designFoundation design

Rotary type machinesy yp


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Reciprocating type machines


• The above are only approximate values.

• Actual permissible should be given by the Machine Vendor/Manufacturer

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Foundation Sizing ( Block Foundation Sizing ( Block foundation):foundation):

• Foundation should be dimensioned in such a way that the derived eccentricity, in botha way that the derived eccentricity, in both lateral and longitudinal directions is bare minimum.

• In no case it should not exceed 5% of the base dimension in the respective direction


• Foundation should extend by at least 150 mm on all sides of machine base frame

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• The pressure developed in the soil loads due to static loads should not exceed 75% of the allowable safe bearing capacity.

• Though from strength point of view it may appear adequate to keep foundation mass slightly above the machine mass a


mass slightly above the machine mass, a higher mass ratio helps to keep the eccentricity of loading within limits.

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• For rotary machines: foundation mass = 2 5 to 3foundation mass = 2.5 to 3 times of machine mass

• For reciprocating machines: foundation mass= 5 to 8 times


of machine mass

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ReferencesReferences

• 1. Barkan D.D.” Dynamics of bases and Foundations”- Mc Grawhill

• 2. P.Srinivasulu and Vaidyanathan “Hand Book of Machine foundations”-Tata Mc Grawhill

• 3. “Foundations for Industrial Machines: Hand book for Practicing Engineers”- K.G.Bhatia- DCAD publishers

• 4. S.Prakash and V.Kpuri “ Foundation for machines- Analysis and Design”-John Wiley

• 5. Arya, O Neil and Pincus “ Design of Structure and Foundation for Vibrating Machines”- Gulf Publishing

• 6. Indrajit Chowdhury and P.Dasgupta “ Dynamic of Structure and Foundation” –CRC press


Foundation CRC press

• 7. “Soil Dynamics and Machine foundations” – Swami Saran- Galgotia

• 8. “Soil Dynamics “ - Braja M. Das

• 9. Lecture notes: Varanasi Rama Rao B.E, M.S.(I.I.Sc.)

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Q&AQ&A

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Foundation Design.

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