DESIGN AND SIMULATION OF HYDRAULIC SHAKING TABLE ...eprints.utm.my/id/eprint/9658/1/KhairulnizamNgadimonMFKM2006.pdf · actuator system complete with hydraulic system as the power

DESIGN AND SIMULATION OF HYDRAULIC SHAKING TABLE

KHAIRULNIZAM BIN NGADIMON

A project report submitted in partial fulfillment of the

requirements for the award of the degree of

Master of Engineering (Mechanical)

Faculty of Mechanical Engineering

University of Technology Malaysia

7 APRIL 2006

iii

To my beloved family,

The lover in you who brings my dreams comes true,

To my child Luqmanul Hakim and Fatin Nur Atikah, who have brought

a new level of love, patience and understanding

into our lives.

iv

ACKNOWLEDGEMENTS

First and above all, I am very grateful to Allah, with his blessing, allow me

to complete this project on time.

I would like to take this opportunity to express my deep sense of gratitude

and appreciation to my project advisor, Associate Professor Yahaya B. Ramli. His

endless help, useful information, support, advice and guidance have made it possible

for me to finish the project successfully.

I would also like to express my heartfelt thanks to my project co-advisor

Associate Professor Dr. Musa Mailah for the information and motivation to the

project. Not to forget Pn. Rosmawati from Structural Engineering Lab, Faculty of

Civil Engineering UTM Skudai, En. Asmadi from Bahagian Seismologi, Jabatan

Kajicuaca Malaysia for their expert advice. Also thanks to the technicians in the

structural lab for their guidance and technical advice. I am also indebted to Kolej

Universiti Teknologi Tun Hussein Onn and Jabatan Perkhidmatan Awam, Malaysia

for funding my Master study.

Finally, utmost thanks to my parents, my wife Siti Zubaidah and my lovely

son and daughter, there are no words that can replace their support, sacrifice and

encouragement. Last but not least to my colleagues and friends for the livelihood.

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ABSTRACT

Recent industrial progress and computational technology made it possible to

construct more complex structures. Vibration of these structures due to seismic

strength must be measured and proved to prevent them from damage when they are

subjected to earthquake. However, the accuracy of estimating the effect of vibrating

structures is limited by the mathematical models, which are normally simplified

from the actual complex structures. Due to this problem, a study on the development

of shaking table is proposed. The main purpose of this study is to obtain the design

specifications for a 1-axis (horizontal) hydraulic shaking table with medium loading,

which can function primarily as an earthquake simulator and a dynamic structural

testing apparatus. The project employs a three stage electrohydraulic servovalve,

actuator system complete with hydraulic system as the power and drive unit.

Mathematical model for closed loop control experimentation was presented and used

to investigate the influence of various parameters on the overall system. The

investigation includes the study on the effect of controller gain setting (for PD and

AFC), disturbances and system stability. Time domain analysis using computer

simulation was conducted to explain and predict the system’s response. Comparison

between PD and PD-AFC controllers was done and it was found that latter PD-AFC

fulfills the performance and robustness specifications for this project. Other design

outcome that limits the change of disturbances on the system was also identified and

taken as the framework for real world. This suggests that the next stage in

implementation of the designed system can be made for the purpose of an

earthquake simulator, since it works very well especially at low frequency level of

shaking (0 to 5 Hz).

v

ABSTRAK

Perkembangan dan kemajuan teknologi terkini dalam bidang industri

dan perkomputeran membolehkan struktur bangunan yang lebih kompleks dibina.

Getaran struktur bangunan ini terhadap gegaran sismik perlu diukur dan dibuktikan

untuk mencegah daripada kerosakan teruk apabila gempa bumi sebenar berlaku.

Walaubagaimanapun, untuk struktur yang kompleks, penganggaran kesan

getarannya menggunakan model matematik adalah terhad disebabkan beberapa

anggapan dalam analisa dinamiknya. Disebabkan masalah ini, telah membawa

kepada perkembangan alat lantai gegaran hidraulik. Tujuan utama kajian ini adalah

untuk merekabentuk spesifikasi alat lantai gegaran hidraulik 1 paksi (mendatar) pada

skala beban yang sederhana. Ianya digunakan untuk tujuan simulator gempa bumi

dan untuk menguji pelakuan dinamik sesuatu model atau prototaip struktur. Projek

ini menggunakan peringkat ketiga injap servo elektrohidraulik, sistem penggerak

lelurus dan sistem hidraulik sebagai unit kuasa dan penggerak. Model matematik

untuk ujian kawalan gelung tertutup telah dibincangkan dan digunakan untuk

mengkaji kesan beberapa parameter terhadap keseluruhan sistem. Kesan yang dikaji

termasuk penetapan pemalar pengawal, kesan pengawal PD dan AFC, kesan

gangguan dan kestabilan sistem. Analisa dalam domain masa menggunakan simulasi

komputer telah dijalankan untuk mengenalpasti kelakuan sistem. Perbandingan

antara pengawal PD dan PD-AFC dikaji dan didapati pengawal PD-AFC memenuhi

keperluan spesifikasi sambutan masa dan kelasakannya untuk kajian ini. Parameter

lain hasil daripada simulasi yang menghadkan kelakuan sistem daripada kelakuan

asalnya juga telah dikenalpasti dan dijadikan asas dalam aplikasi sebenar. Secara

keseluruhannya, fasa untuk membangunkan sistem yang telah direkabentuk ini boleh

dilakukan untuk tujuan simulasi gempa bumi kerana ianya berfungsi dengan baik

terutamanya pada lingkungan frekuensi 0 hingga 5 Hz.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE PAGE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

TABLE OF CONTENTS vi

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS/ABBREVIATIONS xvii

LIST OF APPENDICES xxi

1 INTRODUCTION TO SHAKING TABLES

1.0 Project Introduction 1

1.1 Objectives of study 2

1.2 Scope of study 3

1.3 Operation of shaking tables 5

1.4 Types of Hydraulic Shaking Table 7

1.4.1 INOVA-Servo hydraulic testing system 7

1.4.2 ANCO-Model R150-142 Shaking table 9

1.4.3 NIED-E Defense Facility in Japan 10

1.4 Project Scheduling 12

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2 LITERATURE REVIEWS OF EARTHQUAKES

PARAMETER

2.0 Introduction 13

2.1 Magnitude and Intensity of Earthquakes 15

2.2 Representation of Ground Motion 16

2.3 Time Domain Analysis of Earthquake

Ground Motion 18

2.4 Earthquake Estimation using Shaking Table Test 19

2.5 The Use of Servovalve Actuator in Earthquakes

Response Test 20

2.5.1 Testing System in Displacement Control 21

2.6 Summary 24

3 DESIGN METHODOLOGY OF HYDRAULIC

SHAKING TABLE

3.0 Introduction 25

3.1 Design Steps of Hydraulic Circuit 26

3.2 Selection of Hydraulic Fluids 28

3.2.1 Effect of Bulk Modulus 28

3.2.2 Lubricating ability 29

3.3 Actuator Design 29

3.3.1 Calculation of Velocity and

Cylinder’s Pressure 30

3.4 Conductor Sizing for Flow Rate Requirements 32

3.4.1 Pressure Rating of Conductors 33

3.4.2 Steel Tubing Conductor 34

3.5 Pressure Relief Valve 35

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3.6 Pump Performance 36

3.6.1 Pump Selection 38

3.7 Summary 40

4 ACTUAL DESIGN CALCULATION

4.0 Introduction 41

4.1 Determination of Dynamic Force Acting

on the Actuator 41

4.2 Determination of Minimum Size of

Piston Diameter 43

4.3 Selection of Cylinder’s Mounting 44

4.4 Determination of Minimum Rod Diameter 45

4.5 Determination of Flow Rate at Different

Frequency Rating 47

4.6 Selection of Conductor for Pressure Line 52

4.7 Selection of Flexible Hydraulic Hose 53

4.8 Calculation of Theoretical Pump Power 53

4.9 Selection of Pump 56

4.10 Selection of Motor 58

4.11 Design of Hydraulic Reservoir 59

4.12 Selection of Conductor for Pump Suction Line 61

4.13 Selection of Hydraulic Fluid 62

4.14 Filter Positioning 63

4.15 Cooling System 63

4.16 The Shaking Table and Actuator Structure 65

4.17 Roller Rail System 67

4.18 Final Specifications of the Designed System 67

4.19 Summary 70

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5 SYSTEM MODELING OF HYDRAULIC SHAKING TABLE

5.0 Introduction 71

5.1 Determination of Natural Frequency and

Damping Ratio of Hydraulic Servomechanism 72

5.2 Actual Modeling of Servovalve Used in the Study 75

5.2.1 Servovalve Flow Property 77

5.2.2 Parameter Identification 80

5.2.3 Servovalve Transfer Function 81

5.3 The Proposed Controller Design 83

5.3.1 PID Controller 84

5.3.2 Active Force Control (AFC ) Controller 89

5.4 Interconnection of Servovalve Controller 86

5.5 Interconnection of Servovalve and

Hydraulic Actuator 88

5.6 Overall System Dynamics 95

5.7 Summary 97

6 SIMULATION

6.0 Introduction 98

6.1 Simulation of Servovalve 98

6.1.1 Performance Specifications 99

6.2 Simulation to Step Input Signal 101

6.3 Response Behavior with Sine Wave Input 103

6.4 Simulation of Servovalve and Actuator 105

6.4.1 Performance Specifications 106

6.5 Response Test without Any Controller 107

6.6 Response of PD-AFC controller to

Step Input Signal 109

x

6.7 Response of PD-AFC Controller to Sine Wave 111

6.8 Robustness of PD-AFC to Disturbances 114

6.8.1 Effect of Shaking Table Loading 114

6.8.2 Effect of Leakage 117

6.8.3 Effect of Dry and Viscous Friction 120

6.8.4 Effect of Hydraulic Fluid Compressibility 122

6.8.5 Effect of Change in Volume 125

6.9 Stability of the System 127

6.9 Summary 129

7 CONCLUSION 131 - 132

REFERENCES 133 - 134

Appendices A – M 135 - 165

xi

LIST OF TABLES

TABLE NO. TITLE PAGE

1.1 Comparison of hydraulic and electric shaking table 2

2.1 Acceleration-magnitude relationship 16

3.1 Factor of safety selection based on pressure 34

4.1 Maximum flow rate at stroke variations and frequency

of 100 Hz. 50

4.2 Shaking table technical specifications 68

5.1 Static servovalve performance 80

5.2 Parameter identification 81

6.1 Data for rise time for MOOG Series 256 servovalve 101

6.2 Gain setting for both controller mode after tuning 109

6.3 Allowable leakage factor at different frequency

and amplitude. 119

6.4 Effect of compressibility change. 123

6.5 Volume Change Effect to System’s Performance 125

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 All electric shaking table 6

1.2 Servo hydraulic shaking table 6

1.3 Manual shaking table 6

1.4 6 Degree of Freedom Shaking System 8

1.5 3 Degree of Freedom Shaking System 8

1.6 1 Degree of Freedom Shaking System 8

1.7 Close up of the 22 Kip actuator with 3 Stage

Servo Valve 9

1.8 NIED Earthquake Simulator from Japan 11

2.1 Seismic waves P and S wave 14

2.2 Principal term used in describing earthquakes

(a) Geometry (b) transmission 14

2.3 Response Spectra for the 1940 El Centro earthquake 17

2.4 Sample of strong earthquake motion in Time Domain

Analysis 19

2.5 Schematic arrangement of actuator controlled system 22

2.6 System modeling for the servo actuator test 22

2.7 Response of the system subjected to a 12.7 cm

sine wave input (0 to 10 Hz) 23

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3.1 Extending and retracting phase of actuator 30

3.2 Operation of pressure relief valve 36

3.3 Vane pump 39

4.1 Schematic diagram of the actuator and shaking table 42

4.2 Intermediate trunnion mounts. 44

4.3 Summary of the selected cylinder dimension 46

4.4 Spring vibration system 48

4.5 MATLAB programming code 49

4.6 Flow rate vs. frequency at stroke of 2-inch 52

4.7 Selection of double rod double acting cylinder 51

4.8 Hydraulic cycle operating at maximum frequency

of 20 Hz. 55

4.9 Internal design features of the hydraulic reservoir 60

4.10 Baffle plate controls the direction of flow in the

reservoir. 60

4.11 Proposed layout for the power pack unit 61

4.12 Positioning of filters in the system 64

4.13 Oil to air cooler (cross flow type). 65

4.14 Plate ASTM A36 Dimensions. 66

4.15 Hydraulic circuit for the hydraulic shaking table. 69

5.1 Valve and actuator arrangement 72

5.2 Cutaway view of a 3 stage model 256

MOOG Servovalve. 76

5.3 Schematic of main stage spool valve with actuator

(a) load flow orifice (b) leakage flow orifice 77

5.4 Flow curve for the MTS 256.25A-02 Servovalve 80

5.5 Schematic diagram of AFC loop in the modeling 85

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5.6 3 Stage servovalve and actuator with feedback 87

5.7 Block diagram model of 3-stage servovalve 88

5.8 Equivalent scheme for hydraulic actuator 88

5.9 Equivalent scheme servovalve and actuator 89

5.10 Influence of loading at the actuator 89

5.11 Equivalent scheme including compressibility and

balance flow. 91

5.12 Equivalent scheme including damping factor 92

5.13 Feedback loop from actuator 93

5.14 Introduction of PID control block 94

5.15 The simplified transfer function for the combined system 95

5.16 Step response of the overall model

(a) MATLAB programming (b) Simulink model 96

6.1 Model of 256 MOOG Servovalve in Simulink. 100

6.2 Rise time plot for MOOG servovalve model 256.25A-02 101

6.3 Final fine-tuning of PID controller

(a) Opening in mm (b) opening in percentage 102

6.4 Enlarge view of overshoot. 102

6.5 Sine wave output response at 100% opening

(a) frequency 1 Hz. (b) frequency 5 Hz. 104

6.6 Sine wave output response at 10 mm opening

(a) at frequency 13 Hz (b) at frequency 20 Hz. 104

6.7 Simulink model of hydraulic shaking table. 106

6.8 (a) Removal of PID block

(b) The AFC Control switch is turn off 108

6.9 Response without any controller. 108

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6.10 Responses at 100% opening using step input signal

(a)=700 MPa (b) =200 MPa 108

6.11 Response after the implementation of controller mode;

(a) PD controller only (b) PD-AFC Controller. 110

6.12 Response at low frequency for PD Control mode

(a) at frequency 1 Hz. (b) at frequency 5 Hz. 111

6.13 Response at intermediate and high frequency

using PD Controller.

(a) at frequency 10 Hz (b) at frequency 20 Hz 111

6.14 Response at low frequency using PD-AFC Control

(a) frequency 1.5 Hz (b) frequency 5 Hz 112

6.15 Response at intermediate and high frequency using

PD-AFC Controller(a) at frequency 10 Hz (b) at frequency 20 Hz. 112

6.16 Response to a random wave signal

using PD-AFC Control 113

6.17 (a) The block setting for changing the weight (in kg)

(b) Mass block diagram in SIMULINK. 115

6.18 Responses at test model weight 500 kg.

(a) frequency 1.5 Hz (b) frequency 20 Hz. 116

6.19 Responses at test model weight 2830 kg

(a) frequency 1.5 Hz (b) frequency 20 Hz. 116

6.20 (a) Block for adjusting leakage factor.

(b) Model representation for leakage in Simulink 117

6.21 Responses using PD-AFC at frequency 2 Hz.

(a) L=2 (b) L=160 118

6.22 Responses using PD-AFC at frequency 10 Hz.

(a) L=2 (b) L=20 118

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6.23 Step response using PD-AFC

(a) L=30 (b) L=5 118

6.24 Leakage control method 120

6.25 Response at the onset of dry and viscous friction

(a) step input test (b)sine wave at f = 5 Hz. 121

6.26 Response using PD-AFC at constant mass of 4330 kg.

(a)=700 MN/m2 (b) =692 MN/m2 123

6.27 Response of PD-AFC at =692 MN/m2

(a) mass of 500 kg (b) mass of 4330 kg 123

6.28 System response for the load of 4330 kg

(a) V=20,000 mm3 (b) V=171806 mm3 126

6.29 Routh diagram. 127

6.30 Parameter positioning in Routh diagram. 129

xvii

LIST OF SYMBOLS / ABBREVIATIONS

- Bulk modulus

V - Volume

dP - Change in pressure

dV - Change in volume

F - Force

- Coefficient of friction

N - Normal force

EQ - Input flow rate into the cylinder’s blank end side

v - Extending velocity of the cylinder rod.

Eq - Output flow rate from the cylinder’s rod end side

'a - Cross sectional area of the piston on the rod end side

A - Cross sectional area of the piston on the blank end side

D - Diameter of piston on the blank end side

d - Diameter of piston on the rod end side

1p - Pressure on the blank end side

2p - Pressure on the rod end side

RQ - Output flow rate from the cylinder’s blank end side

u - Extending velocity of the cylinder rod

Rq - Input flow rate into the cylinder’s rod end side

P - Pressure

Q - Flow rate

averagev - Average extending velocity

BP - Burst pressure

xviii

t - Thickness

0D - Outside diameter

iD - Inside diameter

WP - Working pressure

FS - Factor of safety

S - Tensile strength

V - Volumetric efficiency

m - Mechanical efficiency

0 - Overall efficiency

TQ - Theoretical flow rate

T - Torque

- Angular velocity

theoryW - Theoretical flow rate

actualW - Actual power developed by the pump

W - Viscous friction factor

B - Dry friction

m - Total mass

a - Acceleration

L - Piston rod length

I - Second moment of area

E - Young Modulus

K - Bending coefficient

f - Frequency

- Wavelength

x - Stroke length

t - Time

DV - Fluid displacement

N - Speed rating

xix

dq CC , - Discharge coefficient

SP - Supply pressure

TP - Load pressure

- Density

y - Additional displacement

Vx - Pilot spool displacement

mx - Main spool displacement

ecr ,, - Geometric coefficient

w - Valve spool perimeter

VPV KK , - Valve flow gain

T - Time constant

iV - Voltage error signal

PQ - Pilot stage flow rate

mA - Effective area of main spool valve

dK - Derivative gain

PK - Proportional gain

iK - Integral gain

EM - Estimated mass

aF - Measured force from sensor

activeF - Active force

aK - Servovalve controller gain

fK - LVDT 1 gain

pK - LVDT 2 gain

inV - Input voltage command signal

balQ - Compression flow rate

pistonQ - Volume oil flow because of piston movement

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totalQ - Total flow rate into actuator

rf - Natural frequency (Hz.)

VF - Viscous friction force

L - Leakage factor

leakQ - Leakage flow rate

CG - Overall reduced transfer function

aG - Sensor transfer function

n - Natural frequency (rad/sec)

st - Settling time

rt - Rise time

g - Gravity = 9.81 m/s2

xxi

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Gantt chart of work for first and second 135 - 137

semester.

B Modified Mercalli (MM) Scale 138 - 139

C Linear change of acceleration method 140 - 141

D Cylinder standard BS 5785,

Eaton Actuator and accessories dimension 142 - 145

E Standard hydraulic hose from Parker dimension

and technical data. 146 - 147

F VMQ Series vane pump performance data and

dimensions. 148 - 149

G D.C Motor from ABB Motors Inc. technical data

and dimensions. 150 - 151

H Typical properties of selected engineering materials 152

I Properties of rolled-steel shapes 153

xxii

J Assembly drawing for shaking table and

actuators structure. 155 - 156

K Aluminium cassette and roller shoes

technical data and dimensions. 157 - 158

L Series 256 servovalves product specifications. 159 - 163

M MATLAB close loop programming code. 164 - 165

CHAPTER 1

INTRODUCTION TO SHAKING TABLES

1.0 Project Introduction

Shaking table is a machine that can perform realistic simulation of

earthquakes or any other dynamic loading imposed to the test model or structures.

There are many types of shaking table but it can be classify to its method of

vibration actuation by electrically driven, hydraulically driven and manually driven

shaking table. Shaking table is related to earthquake since much of its parameter is

custom designed to the earthquake’s parameter such as acceleration, displacement,

frequency and stroke.

However hydraulically driven shaking table have more advantages from

other method of actuation. Table 1.1 lists some of the advantages of using hydraulic

shaking table.

2

Table 1.1: Comparison of hydraulic and electric shaking table

Hydraulic shaking table Electric shaking table

1. Can be used for any size of load 1. Limited to small and medium size

load.

2. Some of the parameter such as stroke,

velocity, frequency can be changed

easily depend on application.

2. Most of the time , the parameter have

been set cannot be changed.

1.1 Objectives of Study

The main objectives of this study are:

1. To design a medium hydraulically driven shaking table to be used as an

earthquake simulator.

2. To perform simulation of the designed hydraulic shaking table using

techniques of dynamic system analysis especially in time domain method to

investigate the linearity characteristics between input signal and the desired

output.

3

1.2 Scope of Study

The scope of this study are:

1. Investigate the nature and properties of earthquake and its relation to the

parameter to be used in the design of hydraulic shaking table.

2. Design a complete hydraulic circuit of a medium scale simple hydraulic

shaking table based on selected parameter.

3. Derive the dynamic equation of the hydraulic shaking system and develop a

mathematical model for the overall system.

4. Select a proper practical value for each parameter assigned in the

mathematical model.

5. Perform computer simulation using MATLAB Simulink on the time domain

analysis, feedback system design and to check the stability of the overall

system.

6. All simulations are performed within the limitation of the selected parameter

such as maximum load range, frequency range, shaking axis and maximum

acceleration range.

In this project, the works are bounded in the frequency range of 20 Hz,

maximum acceleration of 1.5g and maximum load of 4330 kg. Main component of

hydraulic circuit and the hydraulic circuit diagrams have been designed and

discussed.

Mathematical modeling of this project is being done on the servovalve and

hydraulic servomechanism using Laplace Transform. Separate modeling will be

4

done that is modeling of servovalve and modeling of actuator mechanism. Not only

that due to nonlinearities in the servovalve, it is better to do a separate modeling of

servovalve so that proper steps can be applied in order to take care of the

nonlinearities. Then the modeling will be combined using block diagram and can be

programmed in the Simulink.

Simulation part will be done in Semester II and the program that will be used

is MATLAB Simulink. In this program the overall block diagram will be

programmed in it and input signal will be imposed on the block diagram. Types of

input signal to be tested are Step, Sinusoidal and Random input signals. Simulation

also being done separately that is simulation of servovalve and combined simulation

of servovalve and actuator to investigate the individual response. A proposed

controller will be added. Then it will be compared and tested against disturbance

effect on the system. Finally, the controller that fulfills the performance and

robustness specifications will be selected. In the simulation, some design limitation

and outcomes will be investigated in order to compensate for any practical changes

that might occur during the actual condition.

This project is important to get the preliminary design of hydraulic shaking

table of medium scale that have many benefit to the future work and development of

this machine. Future research in this field is interesting since it can develop more

realistic design of hydraulic shaking table.

5

1.3 Operation of Shaking Tables

Shaking table is a mechanical device that is used to test any structures under

seismic or other types of dynamic loading such as step load, sinusoidal varying

force, or random load. If the shaking table is designed primarily to test civil structure

under seismic loading, then it is also called earthquake simulator. Normally test

model are developed to understand the effects of different parameters and process

that leads to failure of prototype at a real time. If the test model are performed under

gravitational field of earth, then it is subjected to the shaking table test, whereas if

the model tests are performed under higher gravitational field then it is subjected to

centrifugal test. Therefore shaking table test is an experimental approach in order to

assure the validity of the theoretical estimation of the response of the structure with

the exact dynamic characteristics thus to develop the safety margin of design for the

structure.

In the shaking table test, test specimens are placed on the table and it is fixed

by mechanical fastener or artificial soil compacted on the table. Then the structure

will experience a shaking process at a certain frequency values until a certain time

limit set by the operator. The earthquake simulator or shaking table has a wide range

of applications such as:

Models of buildings or structure in a given scale, subjected to actual

earthquake.

Models of power supply or industrial buildings under specific

dynamic loading conditions.

Mechanical equipment and transportation facilities test

Mechanical testing and development of dampers for power

transmission lines.

6

Shaking table device operates in various means. Some of them use all-

electric servo motor driven type as in Figure 1.1, servo hydraulic means of actuation

for high mass payloads such as in Figure 1.2 and manually operated shaking table as

in Figure 1.3 that use external applied force to shake the table.

Figure 1.1: Electric shaking table [1] Figure 1.2: Servo hydraulic table [1]

Figure 1.3: Manual shaking table [2]

7

1.4 Types of hydraulic shaking table

Since most of the shaking table is used as an earthquake simulator purposes,

there is some of them been used as an apparatus to test the response or frequency of

a structure or a test model. This permits the versatility and wide range of shaking

table model. Shaking table is grouped based on its actuator power, frequency range

and the maximum load it can handle. Normally it is classified either in small scale,

medium scale or a large scale load. Small scale load hydraulic shaking table ranging

from 0 to 1000 kg load whereas for medium scale can range from 1000 to 5000 kg

and large scale range is greater than 5000 kg load. Section 1.4.1, 1.4.2 and 1.4.3

shows some manufacturer of hydraulic shaking table in the market.

1.4.1 INOVA – Servo hydraulic Testing System

INOVA is one of the leaders in seismic simulations for earthquake and

structural research. Their seismic simulator called “Seismic Shaking Table” is used

for seismic qualification and seismic simulation in civil engineering and academic

research into earthquake. INOVA’s seismic shaking tables are designed for

earthquake testing of a wide range of test applications. INOVA systems can be used

to simulate a variety of seismic tests as well as evaluating many different types of

components in vibration and shaking environments. The DOF refers to the number

of shaking axis the machine can apply to the test model. Typical configurations are

one, two, three and six degrees of freedom (DOF) as in Figure 1.4, 1.5 and 1.6.

8

Figure 1.4: 6 DOF shaking system [3] Figure 1.5: 3 DOF shaking system [3]

Figure 1.6: 1 DOF shaking system [3]

The six degrees of freedom hydraulic shaking table machine is intended for

general-purpose vibration tests. It is classified as a large-scale machine .In this

machine, test model can be loaded in one axis or simultaneous axes. Test can be run

in constant amplitude, block program or full simulation with combination of more

than one wave profiles to be simulated simultaneously.

9

1.4.2 ANCO-Model R150.142 shaking table

This servo-hydraulic type-shaking table was used by Columbia University. It

is a medium scale shaking table facility to conduct experimentation in structural

dynamics and particularly to monitor and actively control structures subjected to

earthquake ground motion or other force excitations. The table which was custom

designed by ANCO Engineers for the Civil and Structural Research Engineering

capable of carrying maximum three ton payload on the 5ft x 5 ft table size. The table

is able to shake two ton payload with 3g acceleration (three times the acceleration of

gravity in horizontal direction). Thus the table is ideally suited to seismic

application. The hydraulic actuator can produce a stroke of maximum 10 inch (± 5

inch). The actuator has a three-stage servo-valve controlled by an analog inner-loop

control system and a digital outer loop control system (acceleration feedback based).

Figure 1.7: Close up of the 22 kip actuator with 3 stage servo valve [1]

10

Specifications of ANCO-Model R150.142;

1. Shaking direction : Uni-axial horizontal motion

2. Table size : 5 ft x 5 ft.

3. Peak to peak displacement : 10 inches of double amplitude

4. Peak velocity : 60 inch / sec.

5. Peak acceleration : 3.0g

6. Maximum test specimen weight : 2 tonne

7. Frequency range : 0 – 100 Hz.

8. Servo valve : 3-stage electrohydraulic servovalve.

1.4.3 NIED-E Defense Facility in Japan

Recently due to a number of major damage caused by earthquakes and

structural buildings failure cases in Japan have led to the start of NIED-E Defense

project. National Research Institute for Earth Science and Disaster Prevention

(NIED) have three main objectives that are to conduct research and experimentation

on the structural building failure test, developing three dimensional motion of the

simulated real earthquake from past record earthquake data and build full scale

model to predict the real behavior of the damage. NIED use a big scale shaking table

facility as in Figure 1.8 to test their ready-made full-scale model. Some of the

specifications of the shaking table facilities are;

Shaking table type : 3D Full scale earthquake testing facility

Payload : 1200 ton

Shaking table size : 20m x 15m

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Driving type : Accumulator charge, Electro-hydraulic

Servo control

Shaking direction : X and Y Horizontal, Z – Vertical

Maximum acceleration at

maximum loading. : X, Y Horizontal is > 900 cm/s2

Z-Vertical is >1500 cm/s2

Maximum displacement : X, Y Horizontal is ±100 cm

Z-Vertical is ±50 cm

Figure 1.8: NIED earthquake simulator from Japan [4]

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1.4 Project Scheduling

This project will be done within two semesters. Thus, breakdown of work

structures must be implemented to make sure all the work being done within its

allocated time. In the first Semester, initial literature research work will be done.

This is to get a better picture on how to implement the scope of study number one

until three. In Semester two, scope of study number four until six was performed.

The breakdown of work structures for Semester one and two are attached in the

Appendix A.