i seismic and progressive collapse assessment of...

i

SEISMIC AND PROGRESSIVE COLLAPSE ASSESSMENT OF NEW

PROPOSED STEEL CONNECTION

IMAN FARIDMEHR

A thesis submitted in fulfilment of the

requirements for the award of the degree of

Doctor of Philosophy (Civil Engineering)

Faculty of Civil Engineering

Universiti Teknologi Malaysia

JUNE 2015

iii

In memory of my Father;

To my Mother, Wife and Son to whom I owe everything I

have achieved in my life

iv

ACKNOWLEDGEMENT

This doctoral dissertation is the formal presentation of the research that I

have completed during my three years as a graduate student in the Faculty of Civil

Engineering at the Universiti Teknologi Malaysia. During my graduate studies at

UTM, I received invaluable knowledge, a wealth of advice and generous aid from an

incomparable advisor, extraordinary teachers, wonderful friends and a caring family.

I would like to take this opportunity to thank all those individuals who have helped

me through the completion of this work.

First and foremost, I would like to acknowledge, with the most profound

gratitude, the guidance, counsel and financial aid that I have received from my thesis

advisor Professor Mohd Hanim Osman. Professor Mohd Hanim Osman has taught

me the value of a thorough understanding of the fundamentals of my particular area

of specialization and he has taken the time to help me develop my proficiency as

researcher. For his advice, his help and his guidance, I am eternally indebted.

Finally, I dedicate this thesis to my mother and memory of my father who

passed away during my study. In addition, special thanks go to my wife for her

support and patience during the period of my study and to my son, who give me real

happiness and blessings in my life. Their presence has encouraged me very much to

work on my research and to achieve my goals.

v

ABSTRACT

The disastrous consequences of the partial collapse of the Ronan Point

apartment in 1968 and Northridge earthquake in 1994, exposed the vulnerability of

steel moment frames subjected to extreme loading. The reports of these two

catastrophic events revealed the significant role of beam to column connection where

the damage was mainly formed in this area. In this research, the performance of

three different steel beam to column connections known as SidePlate, reduced beam

section (RBS) and a new proposed “saddlebag” connection subjected to cyclic and

progressive collapse experimentally and numerically were investigated. The main

objective of this research was to evaluate the adequacy of the new proposed

connection to resist extreme loading compared to SidePlate and RBS. Seismic

performance evaluation was focused on the interstory drift angles based on 2010

AISC seismic provisions. In the other hand, investigation of progressive collapse

was associated with satisfaction of acceptance criteria by rotational capacities of the

connections provided in UFC 4-023-03 guideline. The results indicated that the new

proposed connection was capable of achieving adequate rotational capacity of 0.2

radians, two times bigger than acceptance criteria, and developing full inelastic

capacity of the connecting beams during the progressive collapse analysis. In

addition, an excellent cyclic performance was demonstrated by the proposed

connection as plastic hinges only appeared in the connected beams at the interstory

drift angle of 0.06 radians, 1.5 times bigger than acceptance criteria. The seismic

assessment also revealed that the proposed saddlebag connection possess adequate

energy dissipation capacity attained by stable hysteretic behaviour into the inelastic

range. The study also concluded that SidePlate provide adequate performance as it

develop 0.2 radians of plastic hinge rotation angle and 0.06 radians of interstory drift

angle to resist progressive collapse and cyclic loading respectively. However, RBS

connection showed vulnerable performance to resist seismic and progressive

collapse loading where tensile stress mainly appear at the groove welding.

vi

ABSTRAK

Akibat bencana, keruntuhan sebahagian daripada apartmen Ronan Point pada tahun

1968 dan gempa bumi Northridge pada tahun 1994, mendedahkan kelemahan kerangka

keluli di bawah tindakan bebanan melampau. Laporan kedua-dua peristiwa bencana

mendedahkan peranan penting sambungan rasuk tiang di mana kerosakan adalah sebahagian

besarnya terbentuk di kawasan ini. Dalam kajian ini, prestasi tiga sambungan keluli yang

berbeza bagi rasuk ke tiang dikenali sebagai SidePlate, mengurangkan keratan rasuk

dikecilkan (reduced beam section-RBS) dan cadangan baru "saddlebag" di bawah tindakan

keruntuhan kitaran dan progresif secara ujian dan berangka telah disiasat. Objektif utama

kajian ini adalah untuk menilai kecukupan sambungan baru yang dicadangkan untuk

menahan beban yang melampau berbanding SidePlate dan RBS. Penilaian prestasi seismik

telah memberi tumpuan kepada sudut putaran antara tingkat berdasarkan peruntukan garis

panduan seismic 2010. Di sudut lain, penyiasatan keruntuhan progresif dikaitkan dengan

kriteria penerimaan yang memuaskan oleh keupayaan putaran sambungan yang

diperuntukkan dalam garis panduan UFC 4-023-03. Keputusan menunjukkan bahawa

sambungan baru yang dicadangkan mampu mencapai kapasiti putaran mencukupi 0.2 radian,

dua kali lebih besar daripada kriteria yang boleh diterima, dan memberikan keupayan tak-

anjal penuh rasuk sambungan di dalam analisis keruntuhan progresif. Di samping itu,

prestasi kitaran yang sangat baik telah ditunjukkan oleh sambungan “saddlebag” itu di mana

engsel plastik hanya terjadi dalam rasuk yang tersambung pada sudut putaran 0.06 radian,

1.5 kali lebih besar daripada kriteria penerimaan. Penilaian seismik juga mendapati bahawa

sambungan “saddlebag” yang dicadangkan mempunyai keupayaan pelesapan tenaga yang

mencukupi dicapai oleh kelakunan hysteretic yang stabil. Kajian ini juga merumuskan

bahawa SidePlate memberikan prestasi yang mencukupi kerana ia memberikan sudut

putaran ensel plastik 0.2 radian dan 0.06 radian sudut putaran sambungan untuk merintangi

keruntuhan progresif dan beban kitaran masing-masing. Walau bagaimanapun, sambungan

RBS menunjukkan prestasi terendah untuk menanggung beban seismik dan progresif runtuh

di mana tegasan tegangan terutamanya muncul di kimpalan alur.

vii

TABLE OF CONTENTS

CHAPTER

TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xiii

LIST OF FIGURES xiiii

LIST OF ABBREVIATIONS xix

LIST OF SYMBOLS xx

LIST OF APPENDICES xxii

1 INTRODUCTION 1

1.1 Introduction 1

1.2 Background of the Problem 2

1.3 Problem Statement 3

1.4 Significant of Study 5

1.5 Objectives of the Study 7

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1.6 Scope of the Study 8

1.7 Structure of the Thesis 9

2 LITERATURE REVIEW 11

2.1 Introduction 11

2.2 Seismic Performance of Pre-Northridge Connections 12

2.2.1 Previous Studies on Pre-Northridge Connections 16

2.2.2 Fracture Reasons of Pre-Northridge Connection 19

2.3 Seismic Performance of Post-Northridge Connections 20

2.3.1 Types of Post-Northridge Connections 22

2.3.1.1 Reinforced Connections 22

2.3.1.2 Reduced-Beam-Section (RBS) Connections 25

2.3.2 Previous Studies on Post-Northridge connections 26

2.4 Progressive Collapse Phenomenon on Steel Structures 30

2.4.1 Design Consideration Related to Progressive Collapse 31

2.4.1.1 Design Consideration During 1968 to 1975 31



2.4.2 Development of Guidelines 35

2.4.2.1 Direct Design Approach 37

2.4.2.2 Indirect Design Approach 38

2.4.3 General Procedures to Mitigate Progressive Collapse 39

2.4.3.1 Event Control 39

2.4.3.2 Indirect Design 40

2.4.3.3 Direct Design 41

2.4.4 Current Strategy to Resist Against Progressive Collapse 42

2.4.4.1 Strengthening Members 43

2.4.4.2 Redundant Load Path 46

2.4.4.3 Cabling 47

2.4.4.4 Mega Truss 49

2.4.5 Connections Function to Resist Progressive Collapse 50

2.4.6 Previous Studies Related to Progressive Collapse 51

2.5 Summery 59

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3 DESIGN PROCEDURE OF SADDLEBAG, RBS AND SIDEPLATE

MOMENT CONNECTION SUBJECTED TO EXTREME

LOADING 61

3.1 Introduction 61

3.2 Evaluation of Saddlebag Connection to Extreme Loading

Condition 64

3.2.1 Behaviour of Saddlebag under Sudden Column Removal 64

3.2.2 Behaviour of Saddlebag during Cyclic Loading 66

3.3 Design Procedure of Saddlebag Connection 68

3.4 Reliability Analysis for Saddlebag Connection Plate 79

3.5 Design Procedure of RBS and SidePlate to Resist Seismic Loading 89

3.5.1 Reduced Beam Section “RBS” Connection 90

3.5.2 SidePlate Moment Connection System 94

3.5.2.1 Prequalification Limits 96

3.5.2.2 Column-Beam Relationship Limitations 96

3.5.2.3 Design Procedure 98

3.6 Design Consideration to Resist Progressive Collapse 101

3.6.1 Connection Resilience 102

3.6.2 Discrete Beam-To-Beam Continuity 102

3.6.3 Connection Rotational Capacity 103

3.6.4 Determination of Connection Strength Demands 104

3.7 Concluding Remarks 105

4 Experimental And Numerical Simulation 107

4.1 Introduction 107

4.2 Case Studies under Investigation 108

4.3 Loading Protocol and Acceptance Criteria 110

4.3.1 Seismic Assessment 110

4.3.2 Progressive Collapse Assessment 113

4.4 Fabrication Procedure 115

4.5 Experimentation Setup 117

4.5.1 Load Cells 120

4.5.2 Displacement and Rotation Measurements 121

x

4.5.3 Strain Measurement 121

4.5.4 Other Measurements 125

4.6 Material properties 125

4.7 Scaling Procedures 130

4.8 Finite Element Modelling 131

4.8.1 General Features of the Finite Element Modelling 131

4.8.2 FE Program 132

4.8.3 Element Types 132

4.8.4 Boundary Conditions 134

4.8.5 Material Properties 136

4.8.6 Meshing the Model 138

5 RESULTS AND DISCUSSION 141

5.1 Introduction 141

5.2 Seismic Evaluation 141

5.2.1 New Proposed Connection (Saddlebag Connection) 141

5.2.2 Reduced Beam Section “RBS” Connection 146

5.2.3 SidePlate Moment Connection System 149

5.3 Progressive Collapse Evaluation 154

5.3.1 New Proposed “Saddlebag” Connection 154

5.3.2 Reduced Beam Section “RBS” connection 157

5.3.3 Sideplate Moment Connection System 160

5.4 Stiffness Degradation and Energy Dissipation Capacity 165

5.4.1 Stiffness Retention Capacity 165

5.4.2 Energy Dissipation Capacity 167

5.5 Strain Gauge Measurements 170


6 CONCLUSION AND RECOMMENDATIONS 175

6.1 Summary 175


6.3 Recommendations for Future Research 177

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REFRENCES 179

Appendices A-C 189-224

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LIST OF TABLES

TABLE NO. TITLE PAGE

3-1 Values of k for different load and support conditions,

Timoshenko and Gere [110] 74

3-2 Beam and column properties used in the saddlebag connection 80

3-3 Connection plate dimension 82

4-1 Dimension of section used in the case study 109

4-2 Acceptance criteria for fully restrained moment connections [85] 114

4-3 Fundamental scaling factors 130

4-4 Element properties used in this study 133

5-1 Result summaries of seismic evaluation for

new propose connection 145

5-2 Result summaries of seismic evaluation for RBS 149

5-3 Result summaries of seismic evaluation for SidePlate 153

5-4 Summaries of seismic evaluation for all three connection 153

5-5 Result summaries of progressive collapse evaluation

for new proposedspecimen 157

5-6 Result summaries of progressive collapse evaluation

for RBS specimen 160

5-7 Result summaries of progressive collapse evaluation for SidePlate

specimen 163

5-8 summaries of progressive collapse evaluation of all three

connections 164

5-9 Calculation of vertical force and displacement 166

5-10 Vertical peak-to-peak stiffness 167

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

1-1 Monotonic flow curve for low and high strain rates [9] 5

2-1 Typical pre-Northridge complete joint penetration (CJP) welded

flange - bolted web moment connection [13] 12

2-2 Typical fractures in the pre-Northridge connections[20] 14

2-3 Fractures at interface of groove weld and column flange [22] 14

2-4 Divot type fracture in column flange[22] 15

2-5 Fracture through column flange and web[22] 15

2-6 Example of experimental response of pre-Northridge connections 18

2-7 Haunched connection [50] 23

2-8 Coverplated connection [51] 24

2-9 SidePlate system connection [52] 25

2-10 Reduced-beam-section connection, a) straight cut RBS, b) tapered

cut RBS, and c) radius cut RBS [53] 26

2-11 Inability to protect against progressive collapse after the loss of

column, The U.S. General Services Administration GSA [75] 31

2-12 Timeline of major catastrophic events followed by major building

codes changes for progressive collapse mitigation [83] 35

2-13 Examples of strengthening of steel connections [90] 44

2-14 Added load path retrofit concept (a) super-x bracing (b) mega x

bracing [92] 47

2-15 Cabling retrofit concept for implementing a missing column

strategy [93] 48

2-16 Section showing alternative cable placement for cabling

retrofit [93] 48

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2-17 A typical building with top gravity truss system, (a) 3-D view (b)

front and side views [94] 49

2-18 SidePlate retrofit connection [95] 51

2-19 Partial collapse of Ronan point apartment building [96] 52

2-20 Partial collapse of Murrah building [81] 54

2-21 Collapsing of WTC tower [98] 54

2-22 Three-dimensional model created in SAP 2000 by Marjanishvili

et al. [99] 55

2-23 Test setup and concept for blast and push-down test [101] 56

2-24 Post-blast images of a standard moment connection (a) and a side-

plate reinforced blast resistant connection (b) [101] 56

2-25 Push-down on standard moment connection (a) test results and (b)

numerical simulation with explicit FE code LS-DYNA [101] 57

3-1 The new proposed saddlebag connection 62

3-2 Column tree of proposed connection 63

3-3 A sketch depicting a steel frame beam-to-column-to-beam

‘traditional’ moment connection scheme prior to removal of

primary column support [43] 64

3-4 Response after the loss of primary column support that shows the

inability to protect against progressive collapse [43] 65

3-5 Saddlebag connection after sudden column removal (a) deflected

shape, (b) load transfer path and (c) column shear panel zone

condition 65

3-6 Load transfer path from beam to column 66

3-7 Deformation of column shear panel zone, (a) elevation view

(b) plan view 66

3-8 Saddlebag connection after the end of cyclic loading test

(a) deflected shape, (b) load transfer path and (c) column shear panel

zone condition 67

3-9 Load transfer path of saddlebag connection (a) yielding

mechanism and (b) vertical load transfer to the connection plates 69

3-10 Connection plate dimensions 70

3-11 Definition of effective length of groove weld, De 70

xv

3-12 buckling of plate under uni-axial compression,


3-13 Local plate buckling coefficient, k of Eq. 3.10, for plates in

compression with varied boundary conditions,


3-14 Applied load to the connection plate subjected to cyclic loading 75

3-15 3.D views of compression and bending stress applied to the

connection plate 75

3-16 Plate buckling coefficients under compression and bending [111] 76

3-17 Edge conditions of connection plate and proposed buckling

coefficients, k. 77

3-18 Definition of maximum allowable unbraced distance between two

continues beams 79

3-19 Improve shear capacity of connected beams (a) web doubler

plate and (b) diagonal stiffeners 79

3-20 Saddlebag connection plate dimension 81

3-21 Saddlebag connection plate behaviour at the end of progressive

collapse test, buckling coefficient case 1. 83


collapse test, buckling coefficient case 2 84


collapse test, buckling coefficient case 3 85

3-24 Saddlebag connection behaviour at the end of cyclic test, buckling

coefficient case 1 86





3-27 Reduced beam section limitations [113] 91

3-28 Free-body diagram between the centre of RBS and face of the

column [113] 94

3-29 SidePlat moment connection system [114] 95

3-30 Geometric compatibility of SidePlate connection system [113] 97

3-31 Modelling of component stiffness for linear-elastic analysis [113] 99

xvi

3-32 Plastic hinge location and hinge-to-hinge length [113] 101

3-33 Moment gradient for ‘missing column’ scenario to determine

connection strength demand at each critical connection element 105

4-1 Case studies for seismic evaluation (a) new proposed saddlebag

Connection, (b) SidePlate moment connection system (c) reduced

beam section, RBS 108

4-2 Case studies for progressive collapse evaluation (a) new proposed

saddlebag connection, (b) SidePlate moment connection system (c)

reduced beam section, RBS 109

4-3 The loading protocol used for seismic assessment [113] 110

4-4 Moment at column face due to applied load from hydraulic

actuator at beam tip 112

4-5 Definition of interstory drift angle 113

4-6 Definition of connection rotation capacity 114

4-7 Welding transfer and accessories 116

4-8 Test rig for seismic assessment (a) the dynamic actuator (b)

modelling setup 118

4-9 Modeling set up for seismic assessment 118

4-10 The hydraulic jack used for progressive collapse evaluation 119

4-11 Modeling set up for progressive collapse assessment 120

4-12 Strain gauge locations 122

4-13 Strain gauge locations for progressive collapse test 123

4-14 Strain gauge locations for seismic test 124

4-15 Standard tensile test in conformance with ASTM E8 (a) definition

of specimen part and (b) specimen dimension, mm [119] 126

4-16 Tensile test conducted in this study (a) test specimens (b)

failure modes at the end of the test 126

4-17 Test equipment used in the tensile test (a) extensometer, (b)

caliper and (c) universal testing machine 127

4-18 Material properties for true stress-strain and engineering

stress-strain 129

4-19 Element type used in this research 133

4-20 Boundary conditions for seismic assessment 135

4-21 Boundary conditions for progressive collapse assessment 135

xvii

4-22 Validation FE vs experimental tensile test result 136

4-23 Tensile verification test through FEM 137

4-24 Meshing Pattern for Progressive Collapse Evaluation 139

4-25 Meshing Pattern for Seismic Evaluation 140

5-1 Damaged state of new proposed specimen at the end of cyclic test 143

5-2 Numerical results at the end of cyclic loading test of saddlebag

connection (a) plastic equivalent strain and (b) Von-Mises stress

distribution 143

5-3 Moments at column face versus interstory drift angles of new

proposed specimen 145

5-4 Damaged state of the RBS specimen at the end of cyclic test 147

5-5 Numerical results at the end of cyclic loading test of RBS


distribution 147

5-6 Moments at column face versus interstory drift angles of RBS

specimen 148

5-7 Damaged state of SidePlate specimen at the end of cyclic test 150

5-8 Numerical results at the end of cyclic loading test of SidePlate


distribution 151

5-9 Moments at column face versus interstory drift angles of

SidePlate specimen 152

5-10 Damaged state of the new proposed specimen at the end of

progressive collapse test 155

5-11 Numerical results at the end of progressive collapse test of

saddlebag connection (a) plastic equivalent strain and

(b) Von-Mises stress distribution 155

5-12 Vertical force vs. plastic hinge rotation angle of progressive

collapse tests for new propsed specimen 156

5-13 Damaged state of the RBS specimen at the end of progressive

collapse test 158

5-14 Numerical results at the end of progressive collapse test of RBS


distribution 158

xviii


collapse tests for RBS specimen 159

5-16 Damaged state of the SidePlate specimen at the end of

progressive collapse test 161

5-17 Numerical results at the end of progressive collapse test of

SidePlate connection (a) plastic equivalent strain and

(b) Von Mises stress distribution 161


collapse tests for SidePlate specimen 162


collapse tests for all three connections 164

5-20 Definition of rotational peak-to-peak stiffness 166

5-21 Energy dissipated per cycle definition 168

5-22 Calculation of energy dissipated by saddlebag connection 168

5-23 Calculation of energy dissipated by SidePlate connection 169

5-24 Calculation of energy dissipated by RBS connection 169

5-25 Energy dissipated for all three connections 170

5-26 Strain gauge reading of beam flange for progressive collapse test 171

5-27 Strain gauge reading of beam flange for seismic evaluation 171

xix

LIST OF ABBREVIATIONS

AISC - American Institute of Steel Construction

APM - Alternate Path Method

ASD - Allowable Strength Design

ASCE - American Society of Civil Engineers

ASTM - American Society for Testing and Materials

BWWF - Bolted Web-Welded Flange

DCR - Demand Capacity Ratio

DoD - Department of Defence

ELR - Enhanced Local Resistance

FEMA - Federal Emergency Management Agency

FEM - Finite Element Method

GMAW - Gas Metal Arc Welding

GSA - General Services Administration

IBC - International Building Code

LRFD - Load and Resistance Factor Design

LVDT - Linear Variable Displacement Transducer

MRF - Moment Resistant Frame

RBS - Reduced Beam Section

SMF - Special Moment Frames

SMRF - Special Moment Resistant Frame

UFC - Unified Facilities Criteria

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LIST OF SYMBOLS

F - Force

g - Gravity = 9.81 m/s2

I - Moment of inersia

mpb - Expected flexural strengths of beams in saddlebag connection

vg - Shear force from connected beams to saddlebag connection plate

m - Mass

d1 - Horizontal distance between two connection plates

R՛w - weld strength per unit length

k - Plate buckling coefficient

ry - Radius of gyration about y-axis

bfb - beam flange width

tfb - beam flange thickness

twb - beam web thickness

θ - Angle

ρ - Density

db - Depth of the beam

dc - Depth of the column

bbf - Width of beam flange

zc - The plastic section modulus of the column

Fy - The minimum specified yield strength

zb - The Plastic section modulus of the beam

Ød - Resistance factor for ductile limit state

Ø - Reduction factor of the allowable stress of the weld

twb - Thickness of beam web

Ry - Adjustment coefficient for material

cpr - Factor to reflect the peak connection strength

xxi

sh - Distance from face of the column to plastic hinge

Mp - Beam plastic moment according to the anticipated yield stress

DL - Dead load

LL - Live load

σE - Engineering stress

εE - Engineering strain

A0 - Original cross-sectional area

P - External axial tensile load

L0 - Original length

Lf - Final length

E - Young's modulus

ν - Poisson’s ratio

xxii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A PROPOSED CONNECTION WITH OTHER

LATERAL RESISTANT SYSTEMS 189

B DESIGN CALCULATION OF TEST SPECIMENS 193

C ACTUATOR AND HYDRAULIC JACK DATA 207

1

CHAPTER 1

INTRODUCTION

1.1 Introduction

Significant damage imposed on beam-to-column connections within steel

structures after the Northridge Earthquake in January, 1994 raised great concerns in

engineering societies[1]. The post-earthquake reports revealed that beam-to-column

joints went through rotation levels way below the intended yield capacity of their

framing members which was different from the design philosophy of such frames.

The steel moment-resisting frame (SMRF) system lost its credibility among

engineers compared to other structural systems due to its premature and brittle

modes of failure. The Northridge earthquake of 1994 is known to have cost millions

of dollars of damage within the building industry.

The damages and deadly outcomes of progressive collapse events throughout

history including the 1968 Ronan Point building catastrophe, the in 1995 along with

the September 11 attacks to the World Trade Center have raised global concerns

among people[2-4]. Such collapses, along with other unpredicted hazards not taken

into account during the design phase, indicate the need to secure the inhabitants of

residential buildings in case of extreme events. Hence, the performance of structures

in case of progressive collapse has become greatly popular among engineering and

scientific communities. Progressive collapse is recognized as a chain failure within

structural members initiated by local damage or failure due to abnormal loading

conditions which ends up in entire or partial collapse of the building [5]. Such

abnormal loading conditions might result from unexpected circumstances, with a

2

very low occurrence possibility, high intensity and short time effect like vehicle

impact, gas explosions and softening members due to fire.

This study is aimed at the behaviour of beam-to-column connections in case

of extreme loading conditions. This is due to the fact that beam-to-column

connections have an important function in resisting such loads within steel

structures. The objective is to evaluate two beam-to-column connections known as

SidePlate and reduced beam section “RBS” to resist progressive collapse and cyclic

loading conditions. Eventually, a new proposed steel beam-to-column connection

will be recommended and compared against the SidePlate and RBS connections. In

the proposed connection, two parallel beams are used to transfer the loads along the

column sides where the beam-to-column connection is provided via a plate that is

attached to the column flange. The configuration of the new proposed connection is

in a manner to make sure that the entire substantial connection deformation/energy

dissipation takes place outside the connection welds, plates and the column. This

connection hires shop fillet-welded construction and column tree-link beam erection

procedure to obtain enhanced cost efficiencies and quality control. This new solution

attempts to avoid brittle fracture for any element in a construction system like plates,

welds and column. Also, this strategy guarantees that the frame rotational

performance could avoid reliance on column web weak panel zone participation. To

sum up, this connection incorporates simplified load paths that are not a function of

brittle, unreliable and indeterminate behaviour mechanism.

1.2 Background of the Problem

The beam-column joints as critical parts of any structural system is believed

to have control over the extent of catenary action as a result of limited rotation

capacity and resistance of the joints. Furthermore, based on the inspections

conducted after the earthquakes, it has been observed that a great deal of brittle

connection damage was incurred on structures, ranging from negligible cracking to

fully served columns or beams. This is an indication of the fact that beam-to-column

connections within steel moment frames play a significant role in resisting extreme

3

loading conditions. Generally, adequate resistance must be provided by these

connections to develop the full capacity in connected beams. This design philosophy

is composed of the so-called “strong-column and weak-beam” scenario along with

the preferred elastic behaviour in beam-to-column connections. It has been widely

accepted that beam-to-column connections are among one of the weakest members

in case of extreme loading conditions. This failure mode type in beams from hinges

is known as the most appropriate condition for maintaining proper global energy-

dissipation with no serious degradation of capacity within the connections. Hence,

understanding the behaviour of steel beam-to-column connections is the first step

towards controlling the general performance of a structure.

Widespread research conducted in countries throughout the world has

revealed the critical aspects of the behaviour of beam-to-column connections. In

non-seismic areas, the buildings are mostly designed to bear gravity loads with less

consideration towards the lateral load effects. Despite the fact that these buildings

are not situated in seismic regions, long-distance explosions or earthquakes could

affect these structures. Therefore, this contradiction to seismic design concept would

make the beam-column joints of these buildings very vulnerable in case of extreme

loading conditions.

1.3 Problem Statement

An old perception within the civil engineering community that states that

structural steel frames designed against earthquake loads i.e. moment and braced

frames demonstrate a higher resistance towards progressive collapse[6]. This means

that seismic detailing and design would be equal to increased performance in case of

progressive collapse. Since no design guidelines regarding progressive collapse issue

have been published by any institution, practitioners and scientists tend to support

the seismic resistant design in occasions where the design objective includes

progressive collapse prevention [7]. No systematic study so far has been performed

to highlight the role of seismic detailing and design on structural system behaviour in

case of progressive collapse. It is noteworthy to mention that an absolutely different

4

kind of demand will be imposed on a structure by seismic forces compared to those

imposed by progressive collapse. For instance, high moment demands will be

created within the connection region of many moment frames through seismic

forces. Yet, as this will be addressed in Chapter 3 in detail, collapse will be

accompanied by big tensile forces that could have an adverse effect on behaviour of

seismically designed connections. Nevertheless, it has not been mentioned in the

literature what kind of beam-to-column connection entails satisfactory robustness to

allow the plastic rotation development at beam ends along with significant tensile

forces. Hence, there is no evidence regarding the complete prediction of behaviour

of seismically designed structures in case of progressive collapse and therefore, it

remains an open issue for further investigations for engineers before being

recommended for real projects.

Another important issue need to take into account on design procedure of

progressive collapse is the dynamic nature of extreme loading. Although the

earthquake is considered as dynamic event, extreme loading events like vehicle

impact, gas explosions and terrorist suicide attacks are listed as strong dynamic

processes entailing very high strain rates occur in flash of a second. A different

response is anticipated for filler metal and welding under high loading rates

compared to low or static loading conditions that proves the dependence of stress-

strain relationship on strain rates [8]. The following is a summary of the main

features of this behavior as shown in Figure. 1.1:

i. The ultimate tensile strength rises slightly with strain rate.

ii. A much higher increase is demonstrated by the yield strength, in

comparison.

iii. The ultimate tensile strain is able to reduce with strain rate.

5

Figure 1-1 Monotonic flow curve for low and high strain rates [9]

Only one steel beam-to-column connection has been introduced so far that

fulfils the requirements for both progressive collapse and cyclic loading. This

connection is known as the SidePlate moment connection system [11] that was

introduced after the disastrous damages of the 1994 Northridge earthquake to secure

structures against manmade and natural catastrophes i.e. progressive collapse and

bombings. In SidePlate connection, no direct attachment exists between the beam

ends and columns; instead, the beams are sandwiched to the column via two resilient

full-depth SidePlates. Nevertheless, construction methods and design configurations

used by the SidePlate moment connection technology have their own disadvantages

in terms of construction. Besides, this connection type entails a field fillet-welded

step to connect the cover plates and steel beams which could be hard to control.

Thus, incorporation of the innovative feature named the “saddlebag” connection

would exclude the drawbacks of the SidePlate along with preserving its advantages.

1.4 Significant of Study

Earthquakes are one of the most feared natural phenomena that are relatively

unexpected and whose impact is sudden due to the almost instantaneous destruction

that a major earthquake can produce. In the aftermath of the past earthquake, damage

to steel special moment frame connections spawned concern about the reliability of

established design and construction procedures. A number of buildings experienced

6

damage in beam-to-column connections that underwent only moderate inelastic

demands. Failures included fractures of the bottom beam flange-to-column flange

complete-joint-penetration groove welds, cracks in beam flanges, and cracks through

the column section. The fractures were a result of the basic connection geometry,

lack of control of base material properties, the use of weld filler metals with inherent

low toughness, uncontrolled deposition rates, inadequate quality control and other

factors.

Meanwhile, in recent times many structures have been subjected to blast

loads due to acts of terrorism and steel frames form a major part of these targeted

structures. Hence the behaviour of structural steel connections subjected to blast

loads is of interest. For facilities subjected to blast loads, the connections details

have been shown to play a major part in the response of the structure of such high

rate dynamic loading. Thus a better understanding of behaviour of structural steel

connections under blast loads is very important. The guidelines currently used for the

design of structural steel connections subjected to dynamic loads induced during

blasts or earthquakes have proved to be inadequate judging from the poor

performance of steel frames during the bombings in recent times and also during

seismic events like the 1994 Northridge earthquake. Important design modifications

were introduced for connections subjected to seismic loads after extensive

assessments of the observed damage. However these modified design details might

prove to be insufficient when subjected to high rate dynamic loads such as those

generated during an explosion. Therefore it is important to assess the behaviour of

such structures under blast loads.

The proposed study aims at providing a better understanding of the behaviour

of steel connections under blast loads through experimental and numerical

simulation. The adequacy of steel connections that were proposed for resistance

against seismic loads will be assessed when these connections are subjected to blast

loads.

7

1.5 Objectives of the Study

In the light of current world developments, engineers are increasingly being

required to consider extreme loading event mitigations as a basic design criterion.

One method of efficiently achieving this goal is to utilize a multi-hazard approach to

structural system selections. Besides, the suggested technology should address

virtually for any design application and/or condition, making design and

implementation an effortless engineering process. The research in this dissertation is

aimed at evaluation of the performance of a new proposed “Saddlebag” beam to

column connection to resist seismic and progressive collapse loading conditions. In

this perspective, the specific objectives of the research are:

i. To assess the performance of the proposed “Saddlebag” connection

during progressive collapse.

ii. To assess the performance of the proposed “Saddlebag” connection

during the cyclic loading condition.

iii. To assess the energy absorption capacity of the proposed “Saddlebag”

connection.

iv. To compare the seismic and progressive collapse performance of

proposed “saddlebag” connection with Reduced Beam Section “RBS”

and SidePlate moment connection system.

v. To verify the accuracy of the experimental results by comparing the

values of plastic rotation angle and cyclic response obtained from the

numerical simulation to those obtained from the experimental study.

8

1.6 Scope of the Study

The experimental and numerical investigation on the behaviour of steel

beam-to-column connections in case of column removal scenario and cyclic loading

was carried out within the scope stated below:

i. Experimental and numerical progressive collapse assessment was

performed under column removal scenario conducted by quasi-static

loading (monotonically increasing force).

ii. The seismic evaluation under cyclic loading was conducted by a

hydraulic actuator installed at the tip of the beam and simulated with

numerical modelling.

iii. The numerical part of the study was conducted using the

commercially available software package (Abaqus/Standard) to

validate the experimental results.

iv. All the specimens were scaled-down to 1/6th of their real scale and

material properties were assumed to be the same for all specimens.

The reason to choose this scale was related to the limited capacity and

length of reacting frame.

9

1.7 Structure of the Thesis

Following is a brief description of the 6 chapters comprising this report.

Chapter 1: Introduction. A general overview of the research program is

given. The objectives and scope of the current study are highlighted and an

introduction to other chapters is presented.

Chapter 2: Literature review. Important topics related to the seismic and

progressive collapse are reviewed including: past studies on seismic and progressive

collapse of structures; building code requirements for prevention of progressive

collapse; structural steels and the process that influence ductile fracture in steels; and

current strategies tom mitigate the progressive collapse hazards.

Chapter 3: Design procedure of saddlebag connection subjected to extreme

loading. Evaluation of saddlebag connection to extreme loading condition were

investigated. Design procedure of saddlebag connection was addressed through a

case study example. Design procedure for RBS and SidePlate to address seismic and

progressive collapse requirements also considered in this chapter.

Chapter 4: Experimental and numerical simulation. Case studies under

investigation were developed for seismic and progressive collapse assessment.

Loading protocol and acceptance criteria for both seismic and progressive collapse

were explained. Fabrication procedure and modelling setup for each loading protocol

explained point by point. Finally the numerical simulation was explained in this

chapter.

Chapter 5: Results and discussion. This chapter presents the experimental and

numerical results for the saddlebag connection subjected to cyclic and progressive

collapse tests conducted in this research. The results grouped into seismic and

progressive collapse performance for saddlebag connection and compared to the

SidePlate and RBS beam to column connections. Stiffness degradation and energy

dissipation capacity of all three connections were also investigated in this chapter.

10

Chapter 6: Conclusion and recommendations. This chapter presents a brief

summary of the report and key conclusions that can be extracted from the research

project. It also includes recommendations for the future research for progressive collapse

studies.

179

REFERENCES

1. Popov, E.P., T.-S. Yang, and S.-P. Chang, Design of steel MRF connections

before and after 1994 Northridge earthquake. Engineering Structures, 1998.

20(12): p. 1030-1038.

2. Zhang, C., Progressive Collapse Under Abnormal Load. 2009: ProQuest.

3. Stewart, M.G., Cost effectiveness of risk mitigation strategies for protection

of buildings against terrorist attack. Journal of Performance of Constructed

Facilities, 2008. 22(2): p. 115-120.

4. Kean, T., The 9/11 commission report: Final report of the national

commission on terrorist attacks upon the United States. 2011: Government

Printing Office.

5. Specification for Structural Steel Buildings "ANSI/AISC 360-05. 2005,

AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC: Chicago,

Illinois.

6. Gurley, C., Progressive collapse and earthquake resistance. Practice

Periodical on Structural Design and Construction, 2008. 13(1): p. 19-23.

7. Kim, J. and T. Kim, Assessment of progressive collapse-resisting capacity of

steel moment frames. Journal of Constructional Steel Research, 2009. 65(1):

p. 169-179.

8. Khan, M., M. Kuntz, and Y. Zhou, Effects of weld microstructure on static

and impact performance of resistance spot welded joints in advanced high

strength steels. Science and Technology of Welding & Joining, 2008. 13(3):

p. 294-304.

9. Arora, A., et al., Strains and strain rates during friction stir welding. Scripta

Materialia, 2009. 61(9): p. 863-866.

10. Tvergaard, V. and A. Needleman, Analysis of the Charpy V-notch test for

welds. Engineering Fracture Mechanics, 2000. 65(6): p. 627-643.

180

11. Zoetemeijer, P., A design method for the tension side of statically loaded,

bolted beam-to-column connections. HERON, 20 (1), 1974, 1974.

12. Uang, C.-M., et al., Seismic response of an instrumented 13-story steel frame

building damaged in the 1994 Northridge earthquake. Earthquake spectra,

1997. 13(1): p. 131-149.

13. Civjan, S.A., M.D. Engelhardt, and J.L. Gross, Retrofit of pre-Northridge

moment-resisting connections. Journal of Structural Engineering, 2000.

126(4): p. 445-452.

14. Tremblay, R., et al., Performance of steel structures during the 1994

Northridge earthquake. Canadian Journal of Civil Engineering, 1995. 22(2):

p. 338-360.

15. Engelhardt, M.D. and T.A. Sabol, Seismic‐resistant steel moment

connections: developments since the 1994 Northridge earthquake. Progress

in structural engineering and materials, 1997. 1(1): p. 68-77.

16. Joh, C. and W.-F. Chen, Fracture strength of welded flange-bolted web

connections. Journal of Structural Engineering, 1999. 125(5): p. 565-571.

17. Whittaker, A., A. Gilani, and V. Bertero, Evaluation of pre-Northridge steel

moment-resisting frame joints. The Structural Design of Tall Buildings,

1998. 7(4): p. 263-283.

18. Ricles, J., et al., Development of improved welded moment connections for

earthquake-resistant design. Journal of Constructional Steel Research, 2002.

58(5): p. 565-604.

19. Lu, L.-W., et al., Critical issues in achieving ductile behaviour of welded

moment connections. Journal of Constructional Steel Research, 2000. 55(1):

p. 325-341.

20. Wang, C.-H. and Y.-K. Wen, Evaluation of pre-Northridge low-rise steel

buildings. I: Modeling. Journal of Structural Engineering, 2000. 126(10): p.

1160-1168.

21. Chi, B., C.-M. Uang, and A. Chen, Seismic rehabilitation of pre-Northridge

steel moment connections: A case study. Journal of Constructional Steel

Research, 2006. 62(8): p. 783-792.

22. Kaufmann, E.J. and S.S.E. Council, Dynamic tension tests of simulated

moment resisting frame weld joints. 1997: Structural Steel Educational

Council.

181

23. Chen, S.-J., C. Yeh, and J. Chu, Ductile steel beam-to-column connections

for seismic resistance. Journal of Structural Engineering, 1996. 122(11): p.

1292-1299.

24. Zhang, J. and P. Dong, Residual stresses in welded moment frames and

implications for structural performance. Journal of structural engineering,

2000. 126(3): p. 306-315.

25. Whittaker, A., M. Constantinou, and P. Tsopelas, Displacement estimates for

performance-based seismic design. Journal of Structural Engineering, 1998.

124(8): p. 905-912.

26. Uang, C.-M., D. Bondad, and C.-H. Lee, Cyclic performance of haunch

repaired steel moment connections: experimental testing and analytical

modeling. Engineering Structures, 1998. 20(4): p. 552-561.

27. Krawinkler, H., and Gupta, A., Seismic demands for the performance

evaluation of steel moment resisting frame structures. 1999, Stanford

University.

28. E.P. Popov, Tsai, K., and S. Wu, Experimental performance of seismic steel

beam-column moment joints. Journal of Structural Engineering, 1995. 121(6):

p. 925-931.

29. Engelhardt, M. and A. Husain, Cyclic-loading performance of welded flange-

bolted web connections. Journal of Structural Engineering, 1993. 119(12): p.

3537-3550.

30. Houghton, D.L., Steel moment resisting frame beam-to-column connections.

1997, Google Patents.

31. Conrad, C., Beam splice connection. 1975, Google Patents.

32. Foutch, D.A., S.C. Goel, and C.W. Roeder, Seismic testing of full-scale steel

building-Part I. Journal of Structural Engineering, 1987. 113(11): p. 2111-

2129.

33. Kim, T., et al., Experimental evaluation of plate-reinforced steel moment-

resisting connections. Journal of Structural Engineering, 2002. 128(4): p.

483-491.

34. Mahin, S., J. Malley, and R. Hamburger, Overview of the FEMA/SAC

program for reduction of earthquake hazards in steel moment frame

structures. Journal of Constructional Steel Research, 2002. 58(5): p. 511-528.

182

35. Mehrabian, A., T. Ali, and A. Haldar, Nonlinear analysis of a steel frame.

Nonlinear Analysis: Theory, Methods & Applications, 2009. 71(12): p. e616-

e623.

36. Uang, C.-M., et al., Cyclic testing of steel moment connections rehabilitated

with RBS or welded haunch. Journal of Structural Engineering, 2000. 126(1):

p. 57-68.

37. Pampanin, S., C. Christopoulos, and T.H. Chen, Development and validation

of a metallic haunch seismic retrofit solution for existing under‐designed RC

frame buildings. Earthquake engineering & structural dynamics, 2006.

35(14): p. 1739-1766.

38. Su, R. and Y. Zhu, Experimental and numerical studies of external steel plate

strengthened reinforced concrete coupling beams. Engineering structures,

2005. 27(10): p. 1537-1550.

39. Usami, T., et al., Seismic performance evaluation of steel arch bridges

against major earthquakes. Part 1: Dynamic analysis approach. Earthquake

engineering & structural dynamics, 2004. 33(14): p. 1337-1354.

40. Jin, J. and S. El-Tawil, Seismic performance of steel frames with reduced

beam section connections. Journal of Constructional Steel Research, 2005.

61(4): p. 453-471.

41. Hedayat, A.A. and M. Celikag, Wedge design: A reduced beam web (RBW)

connection for seismic regions. Advances in Structural Engineering, 2010.

13(2): p. 263-290.

42. Patel, K.V. and W.F. Chen, Nonlinear analysis of steel moment connections.

Journal of Structural Engineering, 1984. 110(8): p. 1861-1874.

43. Richard, R. and R. Radau, Force, stress and strain distribution in FR bolted

welded connections. Proc. Structural Engineering Worldwide, 1998.

44. Chen, C.-C., et al., Cyclic behaviour of unreinforced and rib-reinforced

moment connections. Journal of Constructional Steel Research, 2005. 61(1):

p. 1-21.

45. Lee, K. and D.A. Foutch, Seismic performance evaluation of pre-Northridge

steel frame buildings with brittle connections. Journal of Structural

Engineering, 2002. 128(4): p. 546-555.

183

46. Tsai, K.-C. and E.P. Popov, Seismic panel zone design effect on elastic story

drift in steel frames. Journal of Structural Engineering, 1990. 116(12): p.

3285-3301.

47. Stojadinovic, B., et al., Parametric tests on unreinforced steel moment


48. Committee, S.J.V.G.D., et al., Recommended seismic evaluation and upgrade

criteria for existing welded steel moment-frame buildings. 2000: Fema.

49. Kiran, R. and K. Khandelwal, Experimental studies and models for ductile

fracture in ASTM A992 steels at high triaxiality. Journal of Structural

Engineering, 2013. 140(2).

50. Lee, C.-H. and C.-M. Uang, Analytical modeling and seismic design of steel

moment connections with welded straight haunch. Journal of Structural

engineering, 2001. 127(9): p. 1028-1035.

51. Mehrabian, A., Seismic performance of steel frames with a post-northridge

connection. 2002.

52. Deylami, A. and R. Ashraf. Moment resisting connection with sideplate

(geometric aspect). in Proceedings of 13th World Conference on Earthquake

Engineering (13WCEE). 2004.

53. Jones, S.L., G.T. Fry, and M.D. Engelhardt, Experimental evaluation of

cyclically loaded reduced beam section moment connections. Journal of

Structural Engineering, 2002. 128(4): p. 441-451.

54. Federal Emergency Management Agency (FEMA)., Recommended Seismic

Design Criteria for New Steel Moment-Frame Buildings "FEMA 350",

U.D.o.H. Security, Editor. 2000: United States of America.

55. Plumier, A., et al. Resistance of steel connections to low cycle fatigue. in XIth

European Conference on Earthquake Engineering. Paris. 1998.

56. Engelhardt, M.D., et al., The dogbone connection: Part II. Modern Steel

Construction, 1996. 36(8): p. 46-55.

57. Civjan, S., M. Engelhardt, and J.L. Gross. Experimental program and

proposed design method for the retrofit of steel moment connections. in

Proceedings of the 12th World Conference on Earthquake Engineering.

2000.

184

58. Chen, S.-J. and C.-T. Tu, Experimental study of jumbo size reduced beam

section connections using high-strength steel. Journal of Structural

Engineering, 2004. 130(4): p. 582-587.

59. Chen, C.-C., J.-M. Lee, and M.-C. Lin, Behaviour of steel moment

connections with a single flange rib. Engineering structures, 2003. 25(11): p.

1419-1428.

60. Chi, B. and C.-M. Uang, Cyclic response and design recommendations of

reduced beam section moment connections with deep columns. Journal of


61. Zhang, X. and J.M. Ricles, Seismic behavior of reduced beam section

moment connections to deep columns. Journal of structural engineering,

2006. 132(3): p. 358-367.

62. Lee, C.-H. and J.-H. Kim, Seismic design of reduced beam section steel

moment connections with bolted web attachment. Journal of Constructional

Steel Research, 2007. 63(4): p. 522-531.

63. Gilton, C.S. and C.-M. Uang, Cyclic response and design recommendations

of weak-axis reduced beam section moment connections. Journal of


64. Adan, S.M. and W. Gibb, Experimental evaluation of kaiser bolted bracket

steel moment-resisting connections. Engineering journal, 2009. 46(3): p. 181.

65. Lee, C.-H., et al., Effects of panel zone strength and beam web connection

method on seismic performance of reduced beam section steel moment


66. Pachoumis, D., et al., Cyclic performance of steel moment-resisting

connections with reduced beam sections—experimental analysis and finite

element model simulation. Engineering Structures, 2010. 32(9): p. 2683-

2692.

67. Han, S.W., et al., Rotation capacities of reduced beam section with bolted

web (RBS-B) connections. Journal of Constructional Steel Research, 2012.

70: p. 256-263.

68. Sofias, C., C. Kalfas, and D. Pachoumis, Experimental and FEM analysis of

reduced beam section moment endplate connections under cyclic loading.

Engineering Structures, 2014. 59: p. 320-329.

185

69. Pinto, P.E. and P. Franchin. Assessing existing buildings with Eurocode 8

part 3: a discussion with some proposals. in Background documents for the

“Eurocodes: background and applications” workshop. Brussels, Belgium.

2008.

70. Chou, C.C., et al., Seismic rehabilitation performance of steel side plate

moment connections. Earthquake Engineering & Structural Dynamics, 2010.

39(1): p. 23-44.

71. Malley, J.O., et al., Incorporation of full‐scale testing and nonlinear

connection analyses into the seismic upgrade of a 15‐story steel moment

frame building. The Structural Design of Tall and Special Buildings, 2011.

20(4): p. 472-481.

72. Yu, Q.-S.K., C.-M. Uang, and J. Gross, Seismic rehabilitation design of steel

moment connection with welded haunch. Journal of Structural Engineering,

2000. 126(1): p. 69-78.

73. Lee, C.-H., et al., Cyclic seismic testing of steel moment connections

reinforced with welded straight haunch. Engineering structures, 2003.

25(14): p. 1743-1753.

74. Engelhardt, M.D. and T.A. Sabol, Reinforcing of steel moment connections

with cover plates: benefits and limitations. Engineering Structures, 1998.

20(4): p. 510-520.

75. The U.S. General Services Administration, Progressive Collapse Design

Guidelines Applied to Concrete Moment-Resisting Frame Buildings. 2003:

Washington (DC).

76. Breen, J. and C. Siess. Progressive collapse-Symposium summary. in ACI

Journal Proceedings. 1979. ACI.

77. Bertero, V.V., E.P. Popov, and H. Krawinkler, Effects of Local Instabilities

in Beam-column Subassemblage Behavior. 1971: Instituto Nacional de

Tecnologia Industrial.

78. Taylor, D., Progressive collapse. Canadian Journal of Civil Engineering,

1975. 2(4): p. 517-529.

79. Ellingwood, B.R. and E. Leyendecker, Approaches for design against

progressive collapse. Journal of the Structural Division, 1978. 104(3): p.

413-423.

186

80. Webster, F.A. Reliability of multistory slab structures against progressive

collapse during construction. in ACI Journal Proceedings. 1980. ACI.

81. Prendergast, J., Oklahoma city aftermath. Civil Engineering—ASCE, 1995.

65(10): p. 42-45.

82. Murtha-Smith, E., Alternate path analysis of space trusses for progressive

collapse. Journal of Structural Engineering, 1988. 114(9): p. 1978-1999.

83. El‐Tawil, S. and B. Aguirre, Search and rescue in collapsed structures:

engineering and social science aspects. Disasters, 2010. 34(4): p. 1084-1101.

84. Nair, R.S., Preventing disproportionate collapse. Journal of Performance of

Constructed Facilities, 2006. 20(4): p. 309-314.

85. Department of Defense, Design of Buildings to Resist Progressive Collapse,

UFC 4-023-03. 2010.

86. Kim, T., J. Kim, and J. Park, Investigation of progressive collapse-resisting

capability of steel moment frames using push-down analysis. Journal of

Performance of Constructed Facilities, 2009. 23(5): p. 327-335.

87. Betts, C.P., US Department of Defense Guidance for Security Engineering.

Structures April, 2005.

88. Kasai, K., I. Hodgson, and D. Bleiman, Rigid-bolted repair method for

damaged moment connections. Engineering Structures, 1998. 20(4): p. 521-

532.

89. Crawford, J. Retrofit measures to mitigate progressive collapse. in

NIST/NIBS, Multihazard Mitigation Council National Workshop on

Prevention of Progressive Collapse, Chicago, IL. 2002.

90. Xiao, Y., W. He, and K.-k. Choi, Confined concrete-filled tubular columns.

Journal of Structural Engineering, 2005. 131(3): p. 488-497.

91. ANSI, A., AISC 341-05: Seismic provisions for structural steel buildings.

American Institute of Steel Construction Inc, American Institute of Steel

Construction, Chicago, IL, 2005.

92. Ellingwood, B.R., Mitigating risk from abnormal loads and progressive

collapse. Journal of Performance of Constructed Facilities, 2006. 20(4): p.

315-323.

93. Porte, J.M., Investigation of a Cable Retrofit System for Improving the

Progressive Collapse Resistance of Steel Buildings. 2009, The Pennsylvania

State University.

187

94. El-Sawy, T., Effect of retrofit strategies on mitigating progressive collapse of

multistorey steel frame structures. 2009, Concordia University.

95. Houghton, D.L. and J.E. Karns, Diverse Applications of Structural Blast

Mitigation in Steel Frame Buildings using a Common Connection Geometry.

96. Pearson, C. and N. Delatte, Ronan point apartment tower collapse and its

effect on building codes. Journal of Performance of Constructed Facilities,

2005. 19(2): p. 172-177.

97. Gross, J.L. and W. McGuire, Progressive collapse resistant design. Journal

of Structural Engineering, 1983. 109(1): p. 1-15.

98. Usmani, A., Y. Chung, and J.L. Torero, How did the WTC towers collapse: a

new theory. Fire Safety Journal, 2003. 38(6): p. 501-533.

99. Marjanishvili, S. and E. Agnew, Comparison of various procedures for

progressive collapse analysis. Journal of Performance of Constructed

Facilities, 2006. 20(4): p. 365-374.

100. CSI, S.V., 8, 2002. Integrated Finite Element Analysis and Design of

Structures Basic Analysis Reference Manual. Computers and Structures, Inc.,

Berkeley, California, USA.

101. Karns, J.E., et al. Blast testing of steel frame assemblies to assess the

implications of connection behavior on progressive collapse. in Proceedings

of ASCE 2006 Structures Congress, St. Louis. 2006.

102. Hallquist, J.O., LS-DYNA keyword user’s manual. Livermore Software

Technology Corporation, 2007. 970.

103. Sadek, F., et al., Testing and analysis of steel and concrete beam-column

assemblies under a column removal scenario. Journal of Structural

Engineering, 2011. 137(9): p. 881-892.

104. Construction, A.I.o.S., Seismic provisions for structural steel buildings.

2002: American Institute of Steel Construction.

105. Yang, B. and K.H. Tan, Numerical analyses of steel beam–column joints

subjected to catenary action. Journal of Constructional Steel Research, 2012.

70: p. 1-11.

106. Xu, G. and B.R. Ellingwood, Disproportionate collapse performance of

partially restrained steel frames with bolted T-stub connections. Engineering

Structures, 2011. 33(1): p. 32-43.

188

107. Kim, T., U.S. Kim, and J. Kim, Collapse resistance of unreinforced steel

moment connections. The Structural Design of Tall and Special Buildings,

2012. 21(10): p. 724-735.

108. Development, I.M.o.R.U., Design Procedure of Structures with Saddlebag

Connections,Code 324. 2006.

109. AISC, A.S.D., Plastic Design Specifications for Structural Steel Buildings.

1989, American Institute of Steel Construction, Chicago, IL.

110. Timoshenko, S.P., J.M. Gere, and W. Prager, Theory of elastic stability.

Journal of Applied Mechanics, 1962. 29: p. 220.

111. Brockenbrough, R., G. Johnston, and P.U.S.S. Corporation, USS steel design

manual. 1974: US Steel Corporation.

112. AISC Committee on Specifications, A., Specification for Structural Steel

Buildings (ANSI/AISC 360-10). 2010, American Institute of Steel

Construction, Inc.

113. American Institute of Steel Construction, Prequalified Connections for

Special and Intermediate Steel Moment Frames for Seismic Applications.

2010, AISC Connection Prequalification Review Panel.

114. Dihong Shao, T.H., Full Scale Testing and Project Application of SidePlate

Moment Connection for SMRF Using Deep Columns C. Office of Statewide

Health Planning and Development Sacramento, Editor. 2006.

115. Desai, S., Mechanical properties of ASTM A572 grade 65 steel. 1968: Fritz

Engineering Laboratory, Department of Civil Engineering, Lehigh

University.

116. Lee, C.-H., et al., Simplified nonlinear progressive collapse analysis of

welded steel moment frames. Journal of Constructional Steel Research, 2009.

65(5): p. 1130-1137.

117. Karns, J.E., et al., Behaviour of varied steel frame connection types subjected

to air blast, debris impact, and/or post-blast progressive collapse load

conditions. Austin, TX, United States, 2009: p. 1868-1877.

118. Vlassis, A., et al., Progressive collapse of multi-storey buildings due to failed

floor impact. Engineering Structures, 2009. 31(7): p. 1522-1534.

119. Standard, A., E8-04,“. Standard Test Methods for Tension Testing of

Metallic Materials,” Annual Book of ASTM Standards, 2004. 3.

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