MAZLAN BIN ABU SEMAN - Universiti Malaysia Pahang

BLAST IMPACT ON REINFORCED CONCRETE WALL

MAZLAN BIN ABU SEMAN

Doctor of Philosophy (Civil Engineering)

UNIVERSITI MALAYSIA PAHANG

SUPERVISOR’S DECLARATION

I hereby declare that I have checked this thesis and in my opinion, this thesis is adequate

in terms of scope and quality for the award of the degree of Doctor of Philosophy in

Civil Engineering

_______________________________

(Supervisor’s Signature)

Full Name : DR. SHARIFAH MASZURA BINTI SYED MOHSIN

Position : Senior Lecturer

Date : 2 March 2018

STUDENT’S DECLARATION

I hereby declare that the work in this thesis is based on my original work except for

quotations and citations which have been duly acknowledged. I also declare that it has

not been previously or concurrently submitted for any other degree at Universiti

Malaysia Pahang or any other institutions.

_______________________________

(Student’s Signature)

Full Name : MAZLAN BIN ABU SEMAN

ID Number : PAC11006

Date : 2 March 2018

BLAST IMPACT

ON REINFORCED CONCRETE WALL

MAZLAN BIN ABU SEMAN

Thesis submitted in fulfilment of the requirements

for the award of the degree of

Doctor of Philosophy (Civil Engineering)

Faculty of Civil Engineering and Earth Resources

UNIVERSITI MALAYSIA PAHANG

MARCH 2018

ii

DEDICATION

In the name of Allah, the Most Gracious, the most Merciful. My God, increase me in knowledge.

To my parents and family.

iii

ACKNOWLEDGEMENTS

In the name of Allah, the Most Gracious, the most Merciful. First and foremost I would like to thank my parents and family for their constant support, love and encouragement. I have often relied on them and they have always been there for me. I would like to express my sincere gratitude to my supervisor Dr. Sharifah Maszura Bt. Syed Mohsin for the support and guidance throughout this research. I also would like to thank my friend Prof. Dato’ Dr. Ahmad Mujahid B. Ahmad Zaidi of Universiti Pertahanan Nasional Malaysia (UPNM) and his fellow researcher Dr. Mejar Md Fuad Shah B. Koslan of Royal Malaysian Air Force (RMAF) for their assistance and idea for the blast test. My sincere thanks to the Royal Malaysia Air Force (RMAF) especially Markas Tentera Udara (MTU), Bahagian Kujuruteraan led by Lt. Kol. Mior Aminuddin B. Mior Dahalan for his kind assistance and cooperation between different units to ensure the blast test is possible to conduct. Also thank you to all personnel for their assistance during the blast test. Not to forget, the staff at the Civil Engineering and Earth Resources laboratory especially Mr. Muhammad Nurul Fahkri, Mr. Zu Iskandar, Mr. Muhammad Fadzil and Mr. Mohd Hafiz Al-Kasah for their dedicated laboratory and blast field works that supported my research. I would like to thank my fellow graduate friends, Idayu, Sita, Wae, Aira, Nasrul, Zura, Azimah and Wahida for sharing their experience, knowledge and thought. Also thanks to my fellow outdoor and mountain bike friends being along with me exploring the nature, honestly that is part of the way for me to release some stress and problems occurred along the way to complete my PhD. Finally May Allah blesses those involved directly or indirectly throughout this journey.

vi

TABLE OF CONTENTS

DECLARATION

TITLE PAGE i

DEDICATION ii

ACKNOWLEDGEMENTS iii

ABSTRAK iv

ABSTRACT v

TABLE OF CONTENTS vi

LIST OF TABLES xii

LIST OF FIGURES xiv

LIST OF SYMBOLS xxiv

LIST OF ABBREVIATIONS xxx

CHAPTER 1 INTRODUCTION

1.1 Research Background 1

1.2 Problem Statement 2

1.3 Objective of the Research 4

1.4 Scope of the Research 4

vii

1.5 Significance of the Research 5

1.6 Outline of the Thesis 6

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 7

2.2 Explosion 7

2.3 Blast Load 11

2.3.1 Blast Load Classification 11

2.3.2 Scaling Law 13

2.3.3 TNT Equivalence 14

2.3.4 Blast Loads at Point above Ground 15

2.4 Method to Predict Blast Load 16

2.4.1 Unified Facilities Criteria (UFC) 16

2.4.2 Conventional Weapons Effect (ConWep) 17

2.4.3 Numerical Method 20

2.5 Reinforced Concrete Subjected to Blast Load 20

2.5.1 Experimental Works on Blast Load 22

2.5.2 Structural Behaviour 46

viii

2.5.3 Reinforced Concrete Wall 48

2.6 Structural Response to Dynamic Load 52

2.7 Numerical Modelling 55

2.7.1 Hydrocodes 55

2.7.2 AUTODYN 59

2.8 Summary 67

CHAPTER 3 METHODOLOGY

3.1 Introduction 69

3.2 Blast Overpressure Analysis with Friedlander's Equation 70

3.3 Numerical Modelling RC Wall Subjected to Blast Load in AUTODYN 71

3.3.1 Blast Overpressure Analysis 78

3.3.2 Blast Overpressure Impact on RC Wall 82

3.4 Experimental Work of RC Wall Subjected to Blast Overpressure 87

3.4.1 Blast Test Setup 92

3.5 Numerical Validation for the Experimental Work in AUTODYN 93

3.5.1 Numerical Comparison 96

3.6 Summary 98

ix

CHAPTER 4 NUMERICAL ANALYSIS OF BLAST OVERPRESSURE IMPACT

ON RC WALL

4.1 Introduction 99

4.2 Blast Overpressure Analysis with Friedlander's Equation 99

4.3 Blast Overpressure Analysis in AUTODYN 103

4.3.1 Air Volume Type 1 103




4.4 Blast Overpressure Impact on RC Wall in AUTODYN 120

4.4.1 Preliminary Assessment 121

4.4.2 Mesh Dependency 127

4.4.3 Steel Reinforcement Arrangement 131

4.5 Summary 133

CHAPTER 5 EXPERIMENTAL WORK, NUMERICAL VALIDATION AND

OPTIMISATION OF RC WALL SUBJECTED TO BLAST OVERPRESSURE

5.1 Introduction 136

5.2 Experimental Work 136

x

5.2.1 RC-WT Wall 136

5.2.2 Blast Test 138

5.2.3 Result Analysis on Experimental Work 142

5.3 Numerical Validation on Selected RC-WT Wall 144

5.3.1 Blast Overpressure 144

5.3.2 Stress Due to Blast Overpressure 146

5.3.3 Damage Indicator 148

5.3.4 Strain Propagation 152

5.3.5 Displacement Propagation and Plastic Hinges 158

5.3.6 Strain-time History 160

5.3.7 Kinetic Energy-time History 162

5.4 Numerical Comparison on RC-WTB's Wall 164

5.4.1 Blast Overpressure 164

5.4.2 Stress Due to Blast Overpressure 165

5.4.3 Damage Indicator 167

5.4.4 Strain Propagation 171

5.4.5 Displacement Propagation and Plastic Hinges 175

xi

5.4.6 Strain-time History 178

5.4.7 Kinetic Energy-time History 180

5.4.8 Analysis of Numerical Results 182

5.5 Summary 185

CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions 186

6.2 Recommendations for Future Research 188

REFERENCES 189

APPENDIX A NEWSPAPER CUTTING 197

APPENDIX B TYPICAL REINFORCED CONCRETE CROSS SECTION 198

APPENDIX C INPUT DATA OF MATERIAL MODEL IN AUTODYN 199

APPENDIX D ANALYSIS OF SECTION: ULTIMATE MOMENT

RESISTANCE 204

APPENDIX E BLAST OVERPRESSURE ANALYSIS (RC-WA) 209

xii

LIST OF TABLES

Table 2.1

Arc energy vs. consequences 9

Table 2.2

Blast loading classification 12

Table 2.3 Conversion factors for explosives

15

Table 2.4 Experimental works carried out for RC panel

31

Table 2.5 Experimental work carried out for RC wall

33

Table 2.6 Minimum area of flexural reinforcement

51

Table 2.7 Different erosion criteria, erosion limit and mesh sizes used

66

Table 3.1 Detail of mesh sizes and elements used in the numerical simulation

74

Table 3.2

Input data of CONC-35MPA material model in AUTODYN 74

Table 3.3

Modification on principal-stress tensile-failure for CONC-35MPA

75

Table 3.4

Input data of STEEL-4340 material model in AUTODYN 76

Table 3.5

Employed material data for air, input to the ideal gas EOS 77

Table 3.6

Employed material model for TNT, input to the JWL EOS 77

Table 3.7

Detail of air volume types

78

Table 3.8

Detail of steel reinforcement spacing 83

Table 3.9 Detail of element used in the numerical simulation 85

xiii

Table 3.10 Detail of element used in the numerical simulation (fine)

87

Table 3.11 Detail of steel reinforcement spacing

97

Table 4.1 Comparison of peak overpressure with different grid arrangements

105

Table 4.2 Damage indicator area

124

Table 4.3 Damage indicator area with different element size

129

Table 5.1 Slump test result

137

Table 5.2

Compression test result

137

Table 5.3 RC wall’s backward movement due to blast overpressure

138

Table 5.4 Crack details on total length and maximum width occurred

140

Table 5.5 Detail of the RC wall weights

143

Table 5.6 Recommended and provided steel reinforcement ratio for RC walls

143

Table 5.7 Detail of the RC-WT walls weight

184

Table 5.8 Recommended and provided steel reinforcement ratio for RC-WT walls

184

xiv

LIST OF FIGURES

Figure 1.1

RC wall used at the boundary of Kandahar International Airport

2

Figure 1.2

Transformer and RC wall at Gambang substation 2

Figure 2.1

Blast wave propagation 9

Figure 2.2

Pressure time history of an ideal blast wave 10

Figure 2.3

Blast wave from surface burst 13

Figure 2.4

Simplified geometry of explosive charge on the structure 16

Figure 2.5

Blast pressure parameters for hemispherical TNT surface explosion

17

Figure 2.6

ConWep overpressure analysis result 19

Figure 2.7

Strain rates associated with different types of loading

21

Figure 2.8

Study of RC pavement subjected to blast load 34

Figure 2.9

Study of spall failure of RC slab 34

Figure 2.10

Study of GFRP as retrofitted material 35

Figure 2.11

Study of aluminium foam layer as protection layer 36

Figure 2.12

Blast test for numerical prediction studies 36

Figure 2.13

Investigation on different fibre reinforced polymer 37

Figure 2.14 Study of blast resistance 38

xv

Figure 2.15

Spalling study of RC slab due to blast 39

Figure 2.16

The addition of hybrid steel fibre in NRC 39

Figure 2.17

Response of RC panel with different compressive strength 40

Figure 2.18

Performance of different method used on reinforced concrete 41

Figure 2.19

Study of RC wall subjected to blast load 41

Figure 2.20 Detail of RC wall (mm)

42

Figure 2.21

Study of damage mode and mechanism 43

Figure 2.22

Study of the advantages of FE simulation 43

Figure 2.23

Experimental and numerical studies for NSC and HSC panel response

44

Figure 2.24

Study of OPS as a coarse aggregate 45

Figure 2.25

Typical resistance-deflection curve for flexural response 47

Figure 2.26 Horizontal flexural reinforcement tied outside

50

Figure 2.27 Horizontal flexural reinforcement tied inside

50

Figure 2.28 Joint between wall and footing

50

Figure 2.29 Wall to base structure detail with different hooked directions

51

Figure 2.30 SDOF system subjected to triangular load

52

xvi

Figure 2.31 Typical building structure response to earthquake and blast load

54

Figure 2.32 Response mode of the braced frame structure

54

Figure 2.33 Maximum strength, yield strength and residual strengh surface

60

Figure 2.34 Third invariant depend on stress ! plane

61

Figure 3.1

Flowchart of research work 70

Figure 3.2

ALE solver technique in AUTODYN 71

Figure 3.3

Eight nodes hexahedral element

72

Figure 3.4 Meshed steel reinforcements

72

Figure 3.5

Hexahedra meshing for RC wall

73

Figure 3.6

The 1 m wedge (2D) filled with TNT and air 76

Figure 3.7

Pressure contours in 1 m wedge (3D) during solving progress

77

Figure 3.8

Blast simulation in free field (Air volume Type 1)

79

Figure 3.9

Model of blast test (Air volume Type 2) 80

Figure 3.10

Number of nodes acquired for different air grid arrangements

80

Figure 3.11

Pressure gauges at the wall front surface side 80

Figure 3.12


xvii

Figure 3.13


Figure 3.14

Geometry of the RC wall (in mm) 82

Figure 3.15 RC-WA, A1, A2, A3, A4, A5 and A6

84

Figure 3.16

Modification of steel arrangement of RC-WA for RC-WB and RC-WC

86

Figure 3.17

RC Wall Test A (RC-WTA) 88

Figure 3.18

RC Wall Test B (RC-WTB) 89

Figure 3.19

RC Wall Test C (RC-WTC) 90

Figure 3.20

Strain gauge attached on vertical steel in RC-WT walls

91

Figure 3.21 Slump test

91

Figure 3.22

RC walls during concreting process 92

Figure 3.23 Curing for concrete cube and compression test

92

Figure 3.24

PE4 is mould into ball shape 93

Figure 3.25 Overall view of the test setup

93

Figure 3.26 RC wall placed on the ground in the simulation

94

Figure 3.27

One meter blast overpressure vectors mapped in air volume Type 3-1

95

Figure 3.28

Strain and displacement gauges (RC-WTA) 96

Figure 3.29 Strain and displacement gauges (RC-WTB) 96

xviii

Figure 3.30

Strain displacement gauge (RC-WTB1) 97

Figure 3.31

Strain displacement gauge (RC-WTB2) 97

Figure 4.1 Overpressure distribution on the wall surface

100

Figure 4.2

Overpressure-time history on the wall surface 101

Figure 4.3

Overpressure-time history at 5.486 m away 102

Figure 4.4

Overpressure-time history at 1.219 m away

102

Figure 4.5 Simulated blast overpressure-time history in AUTODYN

103

Figure 4.6

Comparison of blast overpressure-time history 104

Figure 4.7 Blast vectors propagation reaching pressure gauge at 5.486 m away

105

Figure 4.8 Overpressure-time history at 5.486 m away

106

Figure 4.9 Overpressure-time history at 1.219 m away on structure side and free side (Type 2-1)

106


107

Figure 4.11 Overpressure-time history at 1.219 m away on structure and free side (Type 2-2)

108

Figure 4.12 Highest overpressure pattern on the wall surface (Type 2-2)

108

Figure 4.13

Effect of grid refinement and flow out boundary (5.486 m away)

109

Figure 4.14 Effect of grid refinement at 1.219 m away on the structure surface

110

xix

Figure 4.15


Figure 4.16

Overpressure-time history at 5.486 m away (Type 3) 112

Figure 4.17

Effect of grid refinement for overpressure at 5.486 m away 112

Figure 4.18

Overpressure-time history at 1.219 m away on free side 114

Figure 4.19

Highest overpressure-time history at 1.219 m away on structure side

114

Figure 4.20

Effect of grid refinement for overpressure at 1.219 m away on structure side

115

Figure 4.21 Overpressure-time history at 4 ft. away on structure and free side (Type 3-1)

115

Figure 4.22

Highest overpressure pattern on the wall surface (Type 3-1) 116

Figure 4.23

Overpressure-time history at 1.219 m away on structure and free side (Type 3-2)

116


117

Figure 4.25

Highest overpressure-time history at 1.219 m away on structure side

118

Figure 4.26 Effect of mesh refinement for overpressure at 1.219 m away on structure side

118

Figure 4.27

Overpressure-time history at 1.219 m away on structure and free side (Type 4-1)

119


119

Figure 4.29 Overpressure-time history at 1.219 m away on structure and free side (Type 4-1)

120

xx


120

Figure 4.31 Damage indicator (coarse element of 35 mm)

121

Figure 4.32 Displacement-time history (coarse element of 35 mm)

122

Figure 4.33

Displacement propagation (coarse element of 35 mm) 122

Figure 4.34

Damage indicator for different compressive strengths (coarse element of 35 mm)

123

Figure 4.35

Displacement-time history for different compressive strength (coarse element of 35 mm)

124

Figure 4.36

Displacement-time history of different concrete grade (coarse element)

125

Figure 4.37 Displacement-time history with difference steel reinforcement spacing

126

Figure 4.38 Damage indicator (medium element of 20 mm)

128

Figure 4.39 Damage indicator (fine element of 10 mm)

129

Figure 4.40

Effect of mesh refinement on displacement-time history 130

Figure 4.41

Displacement propagation (medium element of 20 mm) 130

Figure 4.42

Displacement propagation (fine element of 10 mm) 131

Figure 4.43

Damage indicator-time history (RC-WB) 132

Figure 4.44

Damage indicator-time history (RC-WC) 133

Figure 4.45 Displacement-time history at top height displacement gauge 133

xxi

Figure 4.46

Peak overpressure at 1.219 m away 134

Figure 5.1

Steel reinforcement tensile test result 137

Figure 5.2

Cracks on the wall surfaces 140

Figure 5.3

Cracks on each sides of the wall 141

Figure 5.4

Cracks compared to plastic ruler 141

Figure 5.5


Figure 5.6

Highest overpressure pattern on the wall surface 146

Figure 5.7

Stress due to blast overpressure (RC-WTA) 147

Figure 5.8

Stress due to blast overpressure (RC-WTB) 148

Figure 5.9

Damage indicator propagation (RC-WTA) 149

Figure 5.10

Damage indicator propagation (RC-WTB) 151

Figure 5.11

Strain propagation (RC-WTA) 154

Figure 5.12

Strain propagation (RC-WTB) 156

Figure 5.13

Displacement and deflection propagation 158

Figure 5.14

Comparison of wall base movement from original location 159

Figure 5.15

Progression of plastic hinges 160

xxii

Figure 5.16

Strain-time history at the back side (RCWTA vs RCWTB) 161

Figure 5.17

Strain-time history at the front side (RCWTA vs RCWTB) 161

Figure 5.18 Kinetic energy-time history at the back side (RCWTA vs RCWTB)

163

Figure 5.19 Kinetic energy-time history at the front side (RCWTA vs RCWTB)

163


164

Figure 5.21 Highest overpressure pattern on the wall surface

165

Figure 5.22 Stress due to blast overpressure (RC-WTB1)

166

Figure 5.23 Stress due to blast overpressure (RC-WTB2)

167

Figure 5.24 Damage indicator propagation (RC-WTB1)

168

Figure 5.25 Damage indicator propagation (RC-WTB2)

170

Figure 5.26 Strain propagation (RC-WTB1)

172

Figure 5.27 Strain propagation (RC-WTB2)

174

Figure 5.28 Displacement and deflection propagation

176

Figure 5.29

Comparison of wall base movement from original location 177

Figure 5.30 Progression of plastic hinges

177

Figure 5.31

Strain-time history at the front side (RC-WTB, B1 and B2) 179

Figure 5.32 Strain-time history at the back side (RC-WTB, B1 and B2) 180

xxiii

Figure 5.33 Kinetic energy-time history at the front side (RCWTB, B1 and B2)

181

Figure 5.34 Kinetic energy-time history at the back side (RCWTB, B1 and B2)

182

Figure 5.35 Blast test and strain failure at 31.62 msec

183

Figure 5.36 Displacement-time history

184

xxiv

LIST OF SYMBOLS

! Failure surface constant

As Cross-sectional area of tension reinforcement

As’ Cross-sectional area of compression reinforcement

!! Sound velocity at ambient condition

! Residual failure surface constant

b Width of section

°C Celsius

!! Decay coefficient

!!,!! Material constant for effective strain to fracture

! Effective depth of tension reinforcement / distance from extreme

compression fibre to centroid of tension reinforcement (inch)

!! Depth of compression reinforcement / distance from extreme

compression fibre to centroid of compression reinforcement (inch)

!! Distance from extreme compression fibre to centroid of compression

reinforcement (inch)

! Young’s modulus

!! Specific internal energy

xxv

!! Energy produced during transformer explosion

!!"#$%&' Ratio of elastic strength to failure surface

!!"# ! Function that limits the elastic deviatoric stresses under hydrostatic

compression

! Vibration frequency

!! Compressive strength

!!" Characteristic concrete cube strength

!! Characteristic strength of reinforcement / yield stress

!! Tensile strength

! Shear modulus

!!"#$%&' Shear modulus (elastic)

!!"#$%&"' Shear modulus (fracture)

!!"#$%&'( Shear modulus (residual)

h Height

I Inertia

! Bulk modulus

! Residual failure surface exponent

xxvi

! Mass

Mu Ultimate moment resistance

! Failure surface exponent

! Pressure

!∗ Normalised pressure

!! Peak pressure load

!! Ambient pressure

!!"# Standard atmosphere pressure

!! Reflected overpressure

!!! Peak negative overpressure

!!! Peak positive overpressure

!!" Incident overpressure

!(!) Pressure at time

!! Zero pressure at

R Stand-off distance

Re Actual effective distance

! Time

xxvii

!! Arrival time of blast wave

!! Positive phase duration of an idealised triangular blast pressure

!! Time to cause maximum dynamic displacement

!! Positive phase duration

! Vibration natural period

!! Thickness of concrete section (inch)

!! Homologous temperature

!!""# Room temperature

!!"#$ Melting temperature

T − Negative phase duration of blast wave

T + Positive phase duration of blast wave

! Velocity of wave front

! Volume

! Displacement response

!! Shear stress

!! Maximum dynamic displacement

xxviii

!!", !! Static displacement

! Velocity

! Acceleration

V1 Volume of gas mixture of pyrolysis product

V2 Volume of air of stoichiometric conditions

!"# Volume of V1 and V2

W Charge weight

!!" Weight of hydrocarbons

!!"! Equivalent weight of TNT

!!"#$%&' Elastic limit surface

!!"#$ Failure surface

!!"#$%&'(∗ Residual failure surface

z Lever arm

! Scaled distance

α Angle of incidence

η Yield factor

! Density

xxix

! Function of !!!

!! Function of !! !

! Circular natural frequency

!!! Concrete compressive strain

!!" Steel strain in tension

!!" Steel strain in compression

!! Effective plastic strain

!! Normalised effective plastic strain rate

! Strain rate

!!"" Geometric strain

! Lode angle

ϴ Support rotation

! Ratio of specific heat

! Stress

xxx

LIST OF ABBREVIATIONS

ALE Arbitrary Langrangian Eulerian

ANFO Ammonium Nitrate Fuel Oil

ASCE American Society of Civil Engineers

BEM Boundary element method

C4 Chemical explosive

CFRP Carbon fibre reinforced polymer

ConWep Conventional Weapons Effect

CRSI Concrete Reinforcing Steel Institute

CSA Canadian Standard Association

CSCM Continuous Surface Cap Model

DIF Dynamic increase factor

DOD Department of Defense

EOS Equation of State

FAE Fuel air explosive

FE Finite element

FEM Finite element method

xxxi

FRC Fibre-reinforced concrete

FRP Fibre reinforced polymer

GFRP Glass Fibre Reinforced Polymer

HOB Height of burst

HSC High strength concrete

HSFRC Hybrid steel fibre reinforced concrete

ft Foot

IEEE Institute of Electrical and Electronics Engineers

JWL Jones-Wilkins-Lee

kg Kilogram

kJ Kilojoule

kV Kilovolt

lbs Pound weight

MJ Mega joule

m Meter

mm Mili meter

msec Mili second

xxxii

MPa Mega pascal

MVA Mega volt ampere

NRC Normal reinforced concrete

NSC Normal strength concrete

NWC Normal weight concrete

PE4 Plastic explosive

PETN Pentaerythrite tetra-nitrate

PEFRC Polyethylene fibre-reinforced concrete

PPFRC Polypropylene fibre-reinforced concrete

PVAFRC Polyvinyl alcoholic fibre-reinforced concrete

RC Reinforced concrete

RHT Reidel, Hiermaier and Thoma

RM Ringgit Malaysia

SDOF Single degree of freedom

SFRC Steel fibre reinforced concrete

SEP Safety explosive agent

TNB Tenaga Nasional Berhad

xxxiii

TNT Trinitrotoluene

UFC Unified Facilities Criteria

UHPFC Ultra-high performance fibre concrete

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MAZLAN BIN ABU SEMAN - Universiti Malaysia Pahang