a study on performance of existing building using ordinary moment resisting frame in seismic zone2a

YANGON TECHNOLOGICAL UNIVERSITY DEPARTMENT OF CIVIL ENGINEERING

A STUDY ON PERFORMANCE OF EXISTING BUILDING USING ORDINARY MOMENT-RESISTING FRAME

IN SEISMIC ZONE 2A

BY

MAUNG THIHA KYAW H.C. 3 (APRIL 2005)

(M.E. THESIS)

JANUARY 2007 YANGON

YANGON TECHNOLOGICAL UNIVERSITY DEPARTMENT OF CIVIL ENGINEERING

A STUDY ON PERFORMANCE OF EXISTING BUILDING USING ORDINARY MOMENT-RESISTING FRAME

IN SEISMIC ZONE 2A

MAUNG THIHA KYAW H.C. 3 (APRIL 2005)

A THESIS SUBMITTED TO THE DEPARTMENT OF CIVIL ENGINEERING

IN PARTIAL FULFILMENT OF THE REQUIERMENTS FOR THE DEGREE OF

MASTER OF ENGINEERING (CIVIL)

JANUARY 2007 YANGON

YANGON TECHNOLOGICAL UNIVERSITY

DEPARTMENT OF CIVIL ENGINEERING

We certify that we have examined, and recommend to the University Steering

Committee for Post Graduate Studies for acceptance the thesis entitled "A STUDY

ON PERFORMANCE OF EXISTING BUILDING USING ORDINARY

MOMENT-RESISTING FRAME IN SEISMIC ZONE 2A" submitted by

Maung Thiha Kyaw, Roll No. H.C. 3 (April 2005) in partial fulfilment of the

requirements for the degree of Master of Engineering.

Board of Examiners:

1. Dr. Khin Than Yu

Professor and Head ……………………….

Department of Civil Engineering, Y.T.U. (Chairman/Supervisor)

2. U Aung Than Win

Lecturer ……………………….

Department of Civil Engineering, W.Y.T.U. (Co-Supervisor)

3. U Myo Min Hlaing

Lecturer and Head ………………………..

Department of Civil Engineering, W.Y.T.U. (Member)

4. U Toe Toe Win

Lecturer ………………………..

Department of Civil Engineering, Y.T.U. (Member)

5. U Saw Htwe Zaw

Director ………………………..

ACECOMS, Satellite Centre (External Examiner)

i

ACKNOWLEDGEMENTS

Firstly, the author would like to express his grateful thanks to his honourable

supervisor, Dr. Khin Than Yu, Professor and Head of Department of Civil

Engineering, Yangon Technological University, for her guidance and invaluable

suggestions throughout the preparation of this study.

The author also would like to express grateful thanks to his co-supervisor,

U Aung Than Win, Lecturer, Department of Civil Engineering, Yangon

Technological University, for his invaluable helps, indispensable guidance, patient

and constructive suggestions.

The author is sincerely thankful to Daw Cho Cho, Associate Professor and

Deputy Head of Department of Civil Engineering, Yangon Technological University,

for her kind invaluable guidance, suggestions and kind help.

The author would like to express his heartfelt gratitude to the board of

examiners of this thesis.

Special thanks are also due to all his teachers of Civil Engineering Department

of Yangon Technological University for their invaluable teaching and careful

guidance.

The author would like to express his deepest gratitude to his parents for their

noble support, encouragement and their unique loving kindness to attain his

destination without any trouble.

Finally, thanks to all who helped him with necessary assistance for this study.

ii

ABSTRACT

Within previous decades, the seismic effects had not been considered when

designed and constructed the buildings. But now, due to the development of

technology and knowledge, the seismic effects had been taken into consideration in

design and construction of the structures.

This study deals with the building which was not considered the seismic

effects and is reviewed with subjected to moderate seismic forces to know the

performance of the building. In this study, twelve-storey reinforced concrete building

(ordinary moment-resisting frame) was considered to investigate the effects of

moderate earthquake but substructure analysis was not considered.

First, the three dimensional model was analysed and designed under gravity

load and wind load. And then, the same model was reanalysed with the effects of

moderate seismic forces (zone 2A). Repeated analyses for this structure were

considered for seismic forces (zone 2A) in both factored and unfactored load

conditions. For analysis and design of without seismic effect, ten load combinations

were considered and then twenty-six load combinations with seismic effects.

Finally, analysis results in main structural components such as axial force and

bending moments for columns, shear, torsion and bending moments for beams were

compared for the performance of ordinary moment-resisting frame under three

different types of analytical conditions described in above. Moreover, storey drifts,

storey displacement and storey shear were also compared in this study.

Structural analysis was carried out by using Extended Three Dimensional

Analysis of Building Systems (ETABS) version 8.4.8 software. Load assumptions and

combinations were considered according to the provisions of Uniform Building Code

– UBC (1997) and American Concrete Institute -ACI 318-99 respectively.

iii

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS i

ABSTRACT ii

TABLE OF CONTENTS iii

LIST OF FIGURES viii

LIST OF TABLES xv

LIST OF SYMBOLS xvi

CHAPTER TITLE

1 INTRODUCTION 1

1.1. General 1

1.2. Objectives of the Study 1

1.3. Scope of the Study 2

1.4. Data of Case Study 2

1.5. Outline of Thesis 2

2 LITERATURE REVIEW 3

2.1. General 3

2.2. Seismic Damage 3

2.3. Correlation of Intensity, Magnitude and Acceleration 4

2.3.1. Peak Ground Acceleration 4

2.3.2. Richter Magnitude Scale 4

2.3.3. Intensity Scale 4

2.4. Seismic Risk Zone 5

2.5. Tall Building Behaviour During Earthquakes 6

2.6. Types of Structural Systems 7

2.7. Moment-Resisting Frame 7

2.8. Types of Moment-Resisting Frames 8

2.8.1. Special Moment-Resisting Frame 8

2.8.2. Intermediate Moment-Resisting Frame 8

2.8.3. Ordinary Moment-Resisting Frame 9

2.9. Reinforced Concrete Beam Behaviour 9

2.10. Columns 10

iv

2.10.1. Axial Compression 10

2.11. Static Analysis Procedure 11

2.12. Building Drift Caused by Lateral Forces 12

2.13. Overview of ETABS Software 13

3 PREPARATION FOR STRUCTURAL ANALYSIS AND DESIGN 14

3.1. Design Parameters and Assumptions for Calculation 14

3.2. Loading 14

3.2.1. Gravity Loads 14

3.2.1.1. Dead load 15

3.2.1.2. Live load 15

3.2.2. Lateral Loads 15

3.2.2.1. Wind load 15

3.2.2.2. Earthquake load 17

3.2.3 Load Combinations 20

3.3. Grouping of Structural Components 21

3.4. Analysing 22

3.5. Analysis Output 22

3.5.1. Analysis Results for Columns 22

3.5.2. Analysis Results for Beams 22

3.5.3. Analysis Results for Storey Drifts, Storey

Displacement and Storey Shear 22

3.6. Concrete Frame Design 22

4 COMPARISON OF ANALYSIS RESULTS 23

4.1. General 23

4.2. Comparison of Storey Drifts 23

4.3. Comparison of Storey Displacements 25

4.4. Comparison of Storey Shear 26

4.5. Comparison of Critical Forces in Columns 27

4.5.1. Comparison of Axial Force for Columns 28

4.5.1.1. Comparison of axial force for corner

columns 28

4.5.1.2. Comparison of axial force for end

columns 29

v

4.5.1.3. Comparison of axial force for interior

columns 30

4.5.2. Comparison of Bending Moment in X Direction for

Columns 34

4.5.2.1. Comparison of bending moment in x

direction for corner columns 34


direction for end columns 36


direction for interior columns 37

4.5.3. Comparison of Bending Moment in Y Direction for

Columns 41

4.5.3.1. Comparison of bending moment in y

direction for corner columns 41


direction for end columns 42


direction for interior columns 43

4.6. Comparison of Critical Forces in Beams 47

4.6.1. Comparison of Shear Force for Beams 47

4.6.1.1. Comparison of shear force for edge beams 47

4.6.1.2. Comparison of shear force for cantilever

beams 50

4.6.1.3. Comparison of shear force for interior

beams 52

4.6.2. Comparison of Torsion for Beams 56

4.6.2.1. Comparison of torsion for edge beams 56

4.6.2.2. Comparison of torsion for cantilever

beams 58

4.6.2.3. Comparison of torsion for interior

beams 60

4.6.3. Comparison of Bending Moment at Support for

Beams 65

vi

4.6.3.1. Comparison of bending moment at support

for edge beams 65


for cantilever beams 67


for interior beams 69

4.6.4. Comparison of Bending Moment at Midspan for

Beams 73

4.6.4.1. Comparison of bending moment at

midspan for edge beams 73


midspan for cantilever beams 75


midspan for interior beams 76

4.7. Comparison of Critical Forces for One Panel Continuous

Beam-Column Frame 81

4.7.1. Comparison of Critical Forces Differences for

Columns 81

4.7.2. Comparison of Critical Forces Differences for

Beams 82

4.8. Discussions on Comparisons 92

4.8.1. Comparison of Storey Drifts 92

4.8.2. Comparison of Storey Displacements 92

4.8.3. Comparison of Storey Shear 92

4.8.4. Comparison of Columns 92

4.8.4.1. Axial force 92

4.8.4.2. Bending moment in x direction 93

4.8.4.3. Bending moment in y direction 93

4.8.5. Comparison of Beams 94

4.8.5.1. Shear force 94

4.8.5.2. Torsion 94

4.8.5.3. Bending moment at support 95

4.8.5.4. Bending moment at midspan 95

vii

4.8.6. Comparison of Critical Forces for One Panel

Continuous Beam-Column Frame 96

4.8.7. Summarised Discussions on Comparisons 96

5 DISCUSSIONS, CONCLUSIONS AND RECOMMENDATIONS 98

5.1. Discussions and Conclusions 98

5.2. Recommendations 099

REFERENCE LIST 100

APPENDICES 101

viii

LIST OF FIGURES

Figure Page

2.1. Moment-Resisting Frame 8

2.2. Behaviour of Reinforced Concrete Beam under Increasing Load 10

3.1. Vertical Distribution of Design Base Shear 19

4.1. Comparison of Storey Drift in X-Direction 24

4.2. Comparison of Storey Drift in Y-Direction 24

4.3. Comparison of Storey Displacement - Ux 25

4.4. Comparison of Storey Displacement - Uy 26

4.5. Comparison of Storey Shear -Vx 27

4.6. Comparison of Storey Shear -Vy 27

4.7. Comparison of Axial Force for Corner Column, C70 28



4.10. Comparison of Axial Force for End Column, C55 29 15

4.11. Comparison of Axial Force for End Column, C69 30 15

4.12. Comparison of Axial Force for Interior Column, C42 30








4.20. Comparison of Bending Moment in X Direction for Corner Column,

C70 34


C41 35

ix


C58 35

4.23. Comparison of Bending Moment in X Direction for End Column,

C55 36

4.24. Comparison of Bending Moment in X Direction for End Column,

C69 36

4.25. Comparison of Bending Moment in X Direction for Interior Column,

C42 37


C44 37


C45 38


C46 38


C53 39


C54 39


C59 40


C60 40

4.33. Comparison of Bending Moment in Y Direction for Corner Column,

C70 41


C41 41


C58 42

4.36. Comparison of Bending Moment in Y Direction for End Column,

C55 42

4.37. Comparison of Bending Moment in Y Direction for End Column,

C69 43

4.38. Comparison of Bending Moment in Y Direction for Interior Column,

C42 43

x


C44 44


C45 44


C46 45


C53 45


C54 46


C59 46


C60 47

4.46. Comparison of Shear Force for Edge Beam - B10 48




4.50. Comparison of Shear Force for Cantilever Beam - B270 50

4.51. Comparison of Shear Force for Cantilever Beam - B273 50

4.52. Comparison of Shear Force for Cantilever Edge Beam - B169 51

4.53. Comparison of Shear Force for Cantilever Edge Beam - B166 51

4.54. Comparison of Shear Force for Interior Beam - B12 52









4.63. Comparison of Torsion for Edge Beam - B10 56



xi


4.67. Comparison of Torsion for Cantilever Beam - B270 58

4.68. Comparison of Torsion for Cantilever Beam - B273 59

4.69. Comparison of Torsion for Cantilever Edge Beam - B169 59

4.70. Comparison of Torsion for Cantilever Edge Beam - B166 60

4.71. Comparison of Torsion for Interior Beam - B12 60









4.80. Comparison of Bending Moment at Support for Edge Beam - B10 65




4.84. Comparison of Bending Moment at Support for Cantilever Beam -

B270 67

4.85. Comparison of Bending Moment at Support for Cantilever Beam -

B273 67

4.86. Comparison of Bending Moment at Support for Cantilever Edge

Beam - B169 68

4.87. Comparison of Bending Moment at Support for Cantilever Edge

Beam - B166 68

4.88. Comparison of Bending Moment at Support for Interior Beam - B12 69








xii


4.97. Comparison of Bending Moment at Midspan for Edge Beam - B10 73




4.101. Comparison of Bending Moment at Midspan for Cantilever Edge

Beam - B169 75

4.102. Comparison of Bending Moment at Midspan for Cantilever Edge

Beam - B166 76

4.103. Comparison of Bending Moment at Midspan for Interior Beam - B12 76









4.112. Comparison of Axial Force Differences for Columns from One Panel

Continuous Beam - Column Frame 81

4.113. Comparison of Bending Moment in X Direction Differences for

Columns from One Panel Continuous Beam - Column Frame 81

4.114. Comparison of Bending Moment in Y Direction Differences for

Columns from One Panel Continuous Beam - Column Frame 82

4.115. Comparison of Shear Force Differences for Beams from One Panel


4.116. Comparison of Torsion Differences for Beams from One Panel


4.117. Comparison of Bending Moment at Support Differences for Beams

from One Panel Continuous Beam - Column Frame 83

4.118. Comparison of Bending Moment at Midspan Differences for Beams

from One Panel Continuous Beam - Column Frame 84

A.1. Three Dimensional View of Case Study Building 101

A.2. First Floor Level Beams and Columns Structure Key Plan 102 55

xiii

A.3. Second Floor Level Beams and Columns Structure Key Plan 103 000 55

A.4. Typical Floor (third to tenth floor) Level Beams and Columns

Structure Key Plan 104 000

A.5. Eleventh Floor Level Beams and Columns Structure Key Plan View 105 55

A.6. Roof Level One Beams and Columns Structure Key Plan View 106

A.7. Concrete Design Sections of Ground Floor Plan View 107

A.8. Concrete Design Sections of First Floor Plan View 108

A.9. Concrete Design Sections of Second Floor Plan View 109

A.10. Concrete Design Sections of Third Floor to Eleventh Floor

Plan View 110

A.11. Concrete Design Sections of Roof Level One Plan View 111

A.12. Concrete Design Sections of Elevation View-1 and Elevation View-9 112

A.13. Concrete Design Sections of Elevation View-2 and Elevation View-8 113

A.14. Concrete Design Sections of Elevation View-3 114





A.19. Frame Span Loads (WALL) of Elevation View-3 119

A.20. Frame Span Loads (WALL) of Elevation View-7 120

A.21. Frame Span Loads (WALL) of Elevation View-I 121

A.22. Frame Span Loads (WALL) of Elevation View-J 122

A.23. Uniform Loads GRAVITY (SUPERDL) of First Floor Plan View 123

A.24. Uniform Loads GRAVITY (SUPERDL) of Third Floor Plan View 124

A.25. Uniform Loads GRAVITY (LIVE) of First Floor Plan View 125

A.26. Uniform Loads GRAVITY (LIVE) of Third Floor Plan View 126

A.27. Axial Force Diagram (COMB2) of Elevation View-E 127

A.28. Axial Force Diagram (COMB2) of Elevation View-7 128

A.29. Bending Moment in X Direction Diagram (COMB3) of Elevation

View-E 129 000


View-E 130 555


View-7 131 555

xiv


View-7 132 555

A.33. Bending Moment in Y Direction Diagram (COMB9) of Elevation

View-E 133 555


View-E 134


View-7 135


View-7 136

A.37. Shear Force Diagram (COMB2) of First Floor Plan View 137

A.38. Shear Force Diagram (COMB20) of First Floor Plan View 138

A.39. Shear Force Diagram (COMB2) of Fifth Floor Plan View 139

A.40. Shear Force Diagram (COMB20) of Fifth Floor Plan View 140

A.41. Torsion Diagram (COMB5) of First Floor Plan View 141

A.42. Torsion Diagram (COMB22) of First Floor Plan View 142

A.43. Torsion Diagram (COMB5) of Fifth Floor Plan View 143

A.44. Torsion Diagram (COMB22) of Fifth Floor Plan View 144

A.45. Bending Moment Diagram (COMB4) of First Floor Plan View 145

A.46. Bending Moment Diagram (COMB19) of First Floor Plan View 146

A.47. Bending Moment Diagram (COMB4) of Fifth Floor Plan View 147

A.48. Bending Moment Diagram (COMB19) of Fifth Floor Plan View 148

A.49. Plan View of Beam and Column Labels 149

B.1. Front Elevation 150

B.2. Side Elevation 151

B.3. Ground Floor and First Floor Plan 152

B.4. Typical Floor (Third Floor to Tenth Floor) Plan 153

B.5. Eleventh Floor Plan 154

B.6. Roof Level One Plan 155

xv

LIST OF TABLES

Table Page

2.1. Approximate Approximate Relationship between Mercalli Intensity

and Peak Ground Acceleration 5

2.2. Approximate Code Maximum Zone Acceleration and Magnitude 6

2.3. Effects of an Earthquake by Zone 6

2.4. UBC-1997 Storey Drift Limitations 13

4.1. Comparison of Storey Drifts without Earthquake and with

Earthquake 23

4.2. Comparison of Storey Displacements without Earthquake and

with Earthquake 25

4.3. Comparison of Storey Shear without Earthquake and with

Earthquake 26

4.4. Comparison of Critical Forces for Columns (One Panel) - Axial

Force 85

4.5. Comparison of Critical Forces for Columns (One Panel) - Bending

Moment in X Direction 86

4.6. Comparison of Critical Forces for Columns (One Panel) - Bending

Moment in Y Direction 87

4.7. Comparison of Critical Forces for Beams (One Panel) - Shear

Force 88

4.8. Comparison of Critical Forces for Beams (One Panel) - Torsion 89

4.9. Comparison of Critical Forces for Beams (One Panel) - Bending

Moment at Support 90

4.10. Comparison of Critical Forces for Beams (One Panel) - Bending

Moment at Midspan 91

xvi

LIST OF SYMBOLS

a acceleration

A amplitude

Ast longitudinal steel area

Ag gross cross sectional area

Ce a factor that combines the effects of height, exposure and gust factor

Cq pressure coefficient which takes into consideration

Ca seismic response coefficient for Na

Cv seismic response coefficient for Nv

D.L dead load

E modulus of elasticity

f’c compressive strength of concrete, cylinder

Ft concentrated force at the top of the structure

fy yield strength of reinforcing steel

g acceleration of gravity

h storey height

hi height above base to level i

hn height above base to level n

hx height above base to level x

I seismic important factor depending on occupancy category

Iw wind important factor

L.L live load

M moment

M Ritcher magnitude

MM modified Mercalli scale

Na,Nv near-source factor

P design wind pressure

PGA peak ground acceleration

qs wind stagnation pressure at a standard height of 33 ft corresponding to the

50 years

xvii

R response modification factor or overstrength factor

T fundamental period of vibration

V total design lateral force or shear at the base

W total weight of the structure, total seismic dead load

W.L wind load

wi, wx portion of W located at or assigned to level i or x respectively

Δm maximum inelastic response displacement

Δs storey drift

CHAPTER 1

INTRODUCTION

1.1. General

In Myanmar, according to political, social and economical demands, bridges,

dams, hydropower plants, high-rise buildings etc., are designed and constructed

nowadays. With the growth of population, high-density living is increasingly adopted

as a solution to a problem of shelter. That is why most of the cities in Myanmar need

various types of high-rise building with safety, serviceability and servicing. In

Yangon area, many high-rise buildings are needed due to the rapid growth of

population. Within previous decades, the seismic effects had not been considered

when the buildings were designed and constructed. But now due to the availability of

referenced books and computer software, it is considered the earthquake effects on the

analysis and design of buildings.

In this study, building which was not considered seismic forces when designed

is reviewed with earthquake effects. To get a reliable analysis and design for high-rise

building, computer aided analysis may be fast and economical method. In this study,

12-storey residential reinforced concrete building is solved by using ETABS

(Extended Three dimensional Analysis on Building Systems) nonlinear version 8.4.8

software.

1.2. Objectives of the Study

The objectives of the study are as follows:

1. To gain knowledge in analysis and design of moment-resisting frames.

2. To have better knowledge in effects of earthquake on building structures.

3. To study the behaviour of structural members in Ordinary Moment-Resisting

Frame.

4. To know the performance of Ordinary Moment-Resisting Frame when

subjected to moderate seismic forces.

2

1.3. Scope of the Study

The scopes of the study to achieve the objectives are as follows:

1. Analysis and design of framing system will be carried out by using ETABS

nonlinear version 8.4.8.

2. Equivalent static loading is used for lateral loads (wind and earthquake

effects).

3. Equivalent static earthquake and wind loads are based on Uniform Building

Code (UBC) 1997.

4. Structural elements are designed according to ACI 318-99.

5. Structural analysis is considered only for linear elastic analysis and the study

was not extended to cases of inelastic material behaviour.

6. Comparison of forces in main structural components:

Column : Axial force and Bending Moment in two directions.

Beam : Shear Force, Torsion and Bending Moment at support

and midspan..

7. Comparison of storey drifts, storey displacements and storey shear.

1.4. Data of Case Study

In this study, 12-storey residential reinforced concrete building (ordinary

moment-resisting frame) is considered as a hypothetical model.

This building is located in seismic zone 2A. Maximum length and width of

building are 136 feet and 126 feet respectively. Height of building is 140 feet above

natural ground level.

1.5. Outlines of Thesis

There are five chapters in this thesis. Chapter one is introduction about this

study. In Chapter two, it explains about the literature review of moment resisting

frame and seismic design. Chapter three represents preparation of data for analysis

and design using ETABS software. In Chapter four, structural analysis, design results

and comparison of member forces are presented. Discussions, conclusions and

recommendations for further purposes are presented in the last Chapter. Books and

articles that were cited in this study are listed in references.

CHAPTER 2

LITERATURE REVIEW

2.1. General

Earthquakes result from the sudden movement of tectonic plates in the earth's

crust. The movement takes place at fault lines, and the energy released is transmitted

through the earth in the form of waves that causes ground motion many miles from

the epicenter. Regions adjacent to active fault lines are the most prone to experience

earthquake.

As the ground moves, inertia tends to keep structure in place, resulting in the

imposition of displacements and forces that can have catastrophic results. The purpose

of the seismic design is to proportion structures so that they can withstand the

displacements and the forces induced by the ground motion. Seismic design has

emphasised the effects of horizontal ground motion, because the horizontal

components of an earthquake usually exceed the vertical component and because

structures are usually much stiffer and stronger in response to vertical loads than they

are in response to horizontal loads.

2.2. Seismic Damage

Structural damage due to an earthquake is not solely a function of the

earthquake ground motion. The primary factors affecting the extent of damage are:

1. Earthquake characteristics such as peak ground acceleration, duration of

strong shaking, frequency content and length of fault rupture.

2. Site characteristics such as distance between the epicenter and structure,

geology between the epicenter and structure, soil conditions at the site, and

natural period of the site.

3. Structural characteristics such as natural period and damping of the structure,

age and construction method of the structure and seismic provisions (i.e.,

detailing) included in the design (Lindeburg and Baradar 2001).

4

2.3. Correlation of Intensity, Magnitude and Acceleration with Damage

Correlation of earthquake intensity, magnitude and acceleration with damage

are possible since many factors contribute to seismic behaviour and structural

performance.

2.3.1. Peak Ground Acceleration

The peak ground acceleration, PGA, is easily measured by a seismometer or

accelerometer and is one of the most important characteristics of an earthquake. The

PGA can be given in various units, including ft/sec2, in/sec2, or m/s2. However, it is

most common to specify the PGA in “g’s” (i.e, as a fraction or percent of gravitational

acceleration) (Lindeburg and Baradar 2001).

%1002.32

2sec/ ×= ftaPGA [U.S.] Equation 2.1

%100386

2sec/ ×= inaPGA [U.S.] Equation 2.2

%10081.9

2/ ×= smaPGA [SI] Equation 2.3

2.3.2. Richter Magnitude Scale

The magnitude, M, of an earthquake is determined from the logarithm to base

ten of the amplitude recorded by a seismometer.

The Richter magnitude, M, is calculated from the maximum amplitude, A, of

the seismometer trace. A0 is the seismometer reading produced by an earthquake of

standard size (i.e, a calibration earthquake). Generally, A0 is 0.94 x 10-5 in (0.001

mm).

Equation 2.4 ⎟⎟⎠

⎞⎜⎜⎝

⎛=

010 A

AlogM

Richter magnitude is expressed in whole numbers and decimal fractions. The

magnitude of an earthquake depends on the length and breadth of the fault slip, as

well as on the amount of slip (Lindeburg and Baradar 2001).

2.3.3. Intensity Scale

The intensity of an earthquake is based on the damage and other observed

effects on people, buildings, and other features. Intensity varies from place to place

5

within the disturbed region. The Modified Mercalli scale consists of 12 increasing

levels of intensity (expressed as Roman numerals the initials MM) that range from

imperceptible shaking to catastrophic destruction. The lower numbers of the intensity

scale generally are based on the manner in which the earthquake is felt by people. The

higher numbers are based on observed structural damage. The numerals do not have a

mathematical basis and therefore are more meaningful to non-technical people than to

those in technical fields.

Although there are some empirical relationships, no exact correlations of

intensity, magnitude, and acceleration with damage are possible since many factors

contribute to seismic behaviour and structural performance.

However, within a geographical region with constituent design and

construction methods, fairly good correlation exists between structural performance

and ground acceleration, because the Mercalli intensity scale is based specially on

observed damage. Approximate relationship between modified Mercalli intensity and

peak ground acceleration are shown in Table 2.1 (Lindeburg and Baradar 2001).

Table 2.1. Approximate Relationship between Mercalli Intensity and Peak Ground

Acceleration

Modified Mercalli Intensity Peak Ground Acceleration (g)

IV 0.03 and below

V 0.03 ~ 0.08

VI 0.08 ~ 0.15

VII 0.15 ~ 0.25

VIII 0.25 ~ 0.45

IX 0.45 ~ 0.60

X 0.60 ~ 0.80

XI 0.80 ~ 0.90

XII 0.90 and above Source: Lindeburg and Baradar (2001)

2.4. Seismic Risk Zone

There are several methods of evaluating the significance of the seismic risk

zones. One method is to correlate the zones with the approximate accelerations and

6

magnitudes, as shown in Table 2.2.

Table 2.2. Approximate Code Maximum Zone Acceleration and Magnitude

Zone Maximum Acceleration Maximum Magnitude

0 0.04g 4.3

1 0.075g 4.7

2A 0.15g 5.5

2B 0.20g 5.9

3 0.30g 6.6

4 0.40g 7.2 Source: Lindeburg and Baradar (2001)

Another interpretation of the significance of the zones is to correlate them to

the effects of an earthquake and the Modified Mercalli intensity as shown in

Table 2.3.

Table 2.3. Effects of an Earthquake by Zone

Zone Effect

0 No damage

1 Minor damage corresponding to MM intensities V and VI; distant earthquake may damage structures with fundamental periods greater than 1.0 sec

2 Moderate damage corresponding to MM intensity VII

3 Major damage corresponding to MM intensity VIII

4 Major damage corresponding to MM intensity VIII and higher Source: Lindeburg and Baradar (2001)

2.5. Tall Building Behaviour During Earthquakes

The behaviour of tall building during an earthquake is a vibration problem.

The seismic motions of the ground do not damage a building by impact as does a

weaker’s ball, or by externally applied pressure such as wind, but rather by internally

generated internal forces caused by vibration of the building mass. An increase in the

mass has two undesirable affects on the earthquake design. First, it results in an

increase in the force, and second, it can cause buckling of vertical elements such as

7

columns and walls when the mass pushing down exerts its force on the member bent

or moved out of the plump by the lateral forces (Taranath 1998).

2.6. Types of Structural Systems

The Uniform Building Code (UBC)-1997 recognises seven major types of

structural systems capable of resisting lateral forces. These systems are as follows:

1. Bearing wall system

2. Building frame system

3. Moment-resisting frames

4. Dual systems

5. Cantilever column building systems

6. Shear wall frame interaction system

7. Undefined system (Lindeburg and Baradar 2001).

2.7. Moment-Resisting Frame

Moment-resisting frames resist forces in members and joints primarily by

flexure and rely on a frame to carry both vertical and lateral loads. Lateral loads are

carried primarily by flexure on the members and joints. Theoretically, joints are

completely rigid.

Moment-resisting frames counteract the horizontal forces of earthquake

through the bending strengths of the beams and columns connected rigidly at their

junctions with one another; of course, this bending is accompanied by shear forces.

Moment-resisting frames can be constructed of concrete, masonry or steel.

From an architectural standpoint, moment-resisting frames have positive and negative

implication.

1. Positive

They allow greater flexibility than shear walls and braced frames in the

functional planning of the building.

2. Negative

They exhibit greater deflections than shear walls and braced frames, so that

the detailing of non-structural elements becomes more problematic.

8

Figure 2.1. Moment-Resisting Frame System

Source: Structures and Codes Institute

2.8. Types of Moment-Resisting Frames

Moment-resisting frames are subdivided on the basis of seismic zones. There

are five types of moment-resisting frames:

1. Steel and concrete special moment-resisting frame (SMRF),

2. Masonry moment-resisting wall frame (MMRWF),

3. Concrete intermediate moment-resisting frame (IMRF),

4. Steel or concrete ordinary moment-resisting frame (OMRF), and

5. Special steel truss moment-resisting frame (STMRF).

These systems provide a sufficient degree of redundancy and have excellent

inelastic response capacities (Lindeburg and Baradar 2001).

2.8.1. Special Moment-Resisting Frame

A moment frame in which members and joints are capable of resisting forces

by flexure as well as along the axis of the members. Special moment-resisting frame

is specially detailed to provide ductile behaviour.

The special moment-resisting frame is appropriate in high seismic risk areas,

especially seismic zone 3 and 4 (Lindeburg and Baradar 2001).

2.8.2. Intermediate Moment-Resisting Frame


by flexure as well as along the axis of the members. Intermediate moment-resisting

frame is designed in accordance with section 1921.8 of UBC 1997.

9

The intermediate moment-resisting frame is appropriate in moderate seismic

risk areas, especially seismic zone 2 (Lindeburg and Baradar 2001).

2.8.3. Ordinary Moment-Resisting Frame


by flexure as well as along the axis of the members.

Ordinary moment-resisting frame is not met special detailing requirements for

ductile behaviour. The ordinary moment-resisting frame is appropriate in minimal

seismic risk areas, especially seismic zone 0 and 1 (Lindeburg and Baradar 2001).

2.9. Reinforced Concrete Beam Behaviour

Plain concrete beams are insufficient as flexural members because the tension

strength in bending is a small fraction of the compression bending. In consequence,

such beams fail on the tension side at low loads long before the strength of the

concrete on the compression side has been fully utilized. For this reason steel

reinforcing bars are placed on the tension side as close to the extreme tension fibre as

is compatible with proper fire and corrosion protection of the steel. In such a

reinforced concrete beam the tension caused by the bending moments is chiefly

resisted by the steel reinforcement, while the concrete alone is usually capable of

resisting the corresponding compression.

When the load on such a beam is gradually increased from zero to the

magnitude that will cause the beam to fail, several different stages of behaviour can

be clearly distinguished. At low loads, as long as the maximum tension stress in the

concrete is smaller than the modulus of rupture, the entire concrete is effective in

resisting stress, in compression on one side and in tension on the other side of the

neutral axis. In addition, the reinforcement, deforming the same amount as the

adjacent concrete, is also subject to tension stresses. The distribution of strains and

stresses in concrete and steel over the depth of the section is as shown in Figure

2.2(c). When the load is further increased, the tension strength of the concrete is soon

reached, and tension cracks develop. The general shape and distribution of these

cracks is also small that they are not objectionable from the viewpoint of either

corrosion protection or appearance. Evidently, in a cracked section that is in a cross

section located at a crack such as a-a in Figure 2.2(d), the concrete does not transmit

any tension stresses. The distribution of strains and stresses at or near a cracked

10

section is that shown in Figure 2.2(e). Figure 2.2(f) shows the distribution of stains

and stresses close to the ultimate load. Eventually the carrying capacity of the beam is

reached (Nilson 1997).

Figure 2.2. Behaviour of Reinforced Concrete Beam under Increasing Load Source: Nilson (1997)

2.10. Column

Columns are defined as members that carry loads chiefly in compression.

Usually columns carrying bending moments as well, about one or both axes of the

cross section, and bending action may produce tensile forces over a part of the cross

section (Nilson 1997).

2.10.1. Axial Compression

Three types of reinforced concrete compression members in use are as

follows:

1. Members reinforced with longitudinal bars and lateral ties.

2. Members reinforced with longitudinal bars and continuous spirals.

3. Composite compression members reinforced longitudinally with structural

11

steel shapes, pipe, or tubing, with or without additional bars, and various types

of lateral reinforcement.

The main reinforcement in columns is longitudinal, parallel to the direction of

the load, and consists of bars arranged in a square, rectangular, or circular pattern. The

ratio of longitudinal steel area Ast to gross cross section Ag is in the range from 0.01 to

0.08 according to ACI Code. The lower limit is necessary to ensure resistance to

bending moment not accounted for in the analysis and to reduce the effects of creep

and shrinkage of the concrete under sustained compression. Ratios higher than 0.08

not only economical, but also would cause difficulty owing to congestion of the

reinforcement, particularly where the steel must be spliced. Generally, the larger

diameter bars are used to reduce placement costs and to avoid unnecessary

congestion.

Columns may be divided into two broad categories: short columns, for which

the strength is governed by the materials and the geometry of the cross section, and

slender columns, for which the strength may be significantly reduced by lateral

directions. Effective lateral bracing, which prevents relative lateral movement of the

two ends of a column, is commonly provided by shear walls, elevator and stair shafts,

diagonal bracing, or a combination of these. Although slender columns are more

common now because of the wider use of high strength materials and improved

methods of dimensioning members, it is still true that most columns in ordinary

practice can be considered short columns (Nilson 1997).

2.11. Static Analysis Procedure

There are two different approaches in seismic design. They are static analysis

and dynamic analysis procedures. Both of which are correct in their own ways. Static

deals with the equilibrium of bodies, that is, those that are either at rest or move with

a constant velocity. The static force procedure is also referred to as the equivalent

static lateral-force procedure. The UBC-97 provides the provisions for determining

base shear by the static lateral-force procedure. The structures considered for this

procedure are mainly regular structures.

The static method may be used for the buildings with the following

characteristics.

1. All structures, regular or irregular, in seismic zone 1 and occupancy categories

4 and 5 in seismic zone 2.

12

2. Regular structures under 240 feet in height with lateral force resistance

provided by systems listed in section 2.2 of this thesis.

3. Irregular structures not more than five stories or 65 feet in height

4. Structures with flexible upper portions supported on a rigid lower portion.

2.12. Building Drift Caused by Lateral Forces

A horizontal force applied to an object tends to push it sideways. If it is

unrestrained at its base, it slides in the direction of the applied force. With buildings,

sliding is counteracted by the frictional sliding resistance between the bottom of the

foundation and the soil and by the lateral bearing resistance of the soil against the

vertical faces of the foundation and the piles. Lateral forces acting above the

foundation push the superstructure sideways until the resistance of the structure

reaches an equilibrium with that force. The amount of horizontal displacement that

occurred is called drift. Drift causes stress in structural seismic elements and non-

structural elements because it forces them into deformed shapes.

Storey drift is the lateral displacement of one level of a structure relative to the

level above or below. In the UBC-1997, drift requirements are based on the strength

design method to conform with newly developed seismic base shear forces. Storey

drifts should be determined using the maximum inelastic response displacement, Δm,

which is defined as the maximum total drift or total stroey drift caused by the design

level earthquake.

Displacement includes both elastic and inelastic contributions to the

deformation. The UBC-1997 requires computation of seismic building drifts based on

the response that occurs during the design earthquake. Displacements Δs are computed

from elastic static analysis using the design seismic forces of the UBC-1997.

Δm = 0.7RΔs Equation 2.5

where Δm = maximum inelastic response displacement

Δs = design level response displacement

R = response modification factor

There are two main reasons to control drift. First, excessive movement in

upper storeys has strong adverse psychological and physical effects on occupants.

Second, it is difficult to ensure structural and architectural integrity with large amount

13

of drift. Excessive drift can be accompanied by large secondary bending moments and

inelastic behaviour. Three components of drift are:

1. column and girder bending and shear

2. joint rotation

3. frame bending

Table 2.4. UBC-1997 Storey Drift Limitations

Structure's Normal Period Calculated Storey Drift Using Δm

T < 0.7 sec (short period structures)

Δm ≤ 0.25h (2.5 % of storey height)

T ≥ 0.7 sec (long period structures)

Δm ≤ 0.2h (2.0 % of storey height)

Source: International Conference of Building Officials (1997)

2.13. Overview of ETABS Software

ETABS (Extended Three Dimensional Analysis of Building Systems) is a

special purpose computer program developed specially for building systems. ETABS

is a versatile and powerful program with many functions. It can share data with other

software such as SAFE, SAP2000 and AutoCAD.

For buildings, ETABS provides automation and specialised options to make

the process of model creation, analyse and design fast and convenient. It provides

tools for laying out floor framing, columns, frames and walls, in either concrete or

steel, as well as technologies for generating automatically gravity and lateral loads,

seismic and wind loads according to the requirements of the selected building code. It

can also design steel frame, concrete frame, composite frame and so on. Moreover,

ETABS provides many analysis results such as bending moments, torsional moment,

shear force, axial force, support reactions and displacements of the structural

members.

CHAPTER 3

PREPARATION FOR STRUCTURAL ANALYSIS AND DESIGN

3.1. Design Parameters and Assumptions for Calculation

Design parameters and assumptions for analysis and design of case study

reinforced concrete building are as follows:

1. Analysis property data

Unit weight of concrete = 150 pcf

Modulus of elasticity of concrete = 2850 x103 psi

Poisson's ratio = 0.2

Coefficient of thermal expansion = 5.5 x 10–6

2. Design property data

Compressive strength of concrete, f'c = 2500 psi

Yield strength of reinforcement, fy = 40000 psi

Shear strength of shear reinforcement, fys = 40000 psi

3.2. Loading

Loading on tall buildings differ from loading on low-rise building in its

accumulation into much larger structural forces, in the increased significance of wind

loading, and in the greater importance of dynamic effects.

There are three types of load considered in this structural analysis and design.

They are gravity loads that include dead load and live load, wind and earthquake

loads.

3.2.1. Gravity Loads

Dead loads are defined as gravity loads that will be accelerated laterally with

the structural frame under earthquake motion.

Live loads are defined as gravity loads that do not accelerate laterally at the

same rate as the structural frame when the structure undergoes earthquake motion.

15

3.2.1.1. Dead load

Data for dead load which are used in structural analysis are as follows:

Unit weight of concrete = 150 pcf

4½ inches thick brick wall weight = 50 psf

9 inches thick brick wall weight = 100 psf

Weight of glass area = 20 psf

Superimposed dead load = 20 psf

Elevator weight = 2 tons

3.2.1.2. Live load

Data for live load which are used in structural analysis are as follows:

Live load on residential area = 40 psf

Live load on office area = 50 psf

Live load on commercial area = 100 psf

Live load on lobby area = 100 psf

Live load on stair = 100 psf

Live load on car parking = 60 psf

Live load on drive way = 250 psf

Live load on roof = 20 psf

3.2.2. Lateral Loads

There are certain loads that are almost always applied horizontally, and these

must often be considered in structural analysis and design. Such loads are called

lateral loads. Some kinds of lateral loads that are important for structures are wind

load and earthquake load.

.

3.2.2.1. Wind load

In designing for wind, the UBC-97 suggested that

1. Wind shall be assumed to come from any horizontal direction.

2. No reduction in wind pressure shall be taken for the shielding effect of

adjacent structures.

3. Structures sensitive to dynamic effects, such as building with a height to width

ratio greater than five, structures sensitive to wind excited oscillations, such as

vortex shedding or icing, and buildings over 400 feet in height, shall be, and

16

any structure may be, designed in accordance with approved national

standards.

The forces exerted by winds on buildings increase dramatically with the

increased in building heights. For building of up to about 10 stories and of typical

proportion, the design is rarely affected by wind load. Above this height, however, the

increase in size of structural member to account for wind loading, incurs a cost

premium that increase progressively with height.

In designing for wind, three types of exposure are considered and the

characteristics of these are as follows:

1. Exposure B has terrain with buildings, forest or surface irregularities, covering

at least 20 percent of the ground level area extending 1 mile or more form the

site.

2. Exposure C has terrain that is flat and generally open, extending ½ mile or

more from the site in any full quadrant.

3. Exposure D represents the most severe exposure in areas with basic wind

speed of 80 miles per hour (mph) or greater and has terrain that is flat and

unobstructed facing large bodies of water over 1 mile or more in width relative

to any quadrant of building site. Exposure D extends inland from the shoreline

¼ mile or 10 times the building height whichever is greater.

Required data used for calculation of wind loads are:

Exposure type = B

Effective height for wind load = 140 feet

Basic wind velocity = 80 mph

The design wind pressure of building for any height is obtained from the

formula that is considered in UBC-97.

P = CeCqqsIw Equation 3.1

where, P = design wind pressure

Ce = combined height, exposure and gust factor coefficient

Cq = pressure coefficient for the structure or portion of structure under

consideration

Iw = importance factor

17

3.2.2.2. Earthquake load

Earthquake load consists of the inertial forces of the building mass that results

from the shaking of its foundation by a seismic disturbance. Other severe earthquake

forces may exist, such as those due to land sliding, subsidence, active faulting below

the foundation, or liquefaction of the local subgrade as a result of vibration. Whereas

earthquakes occur, their intensity is relative inversely proportion to their frequency of

occurrence; severe earthquakes are rare, moderate ones more often, and minor ones

are relatively frequent.

To estimate the seismic loading two general approaches are used; which take

into account the property of the structure and the past records of earthquake in the

region. The first approach, termed the equivalent lateral force procedure and the

second is modal analysis procedure. The later is more complex and longer than the

first.

In the first approach, two steps are included:

1. Determination of design base shear

The UBC (1997) states that structure shall be design to resist a minimum total

lateral seismic load V, which shall be assumed to act no concurrently in orthogonal

directions parallel to the main axes of the structure, where V is computed from the

formula,

Equation 3.2

The total design base shear need not exceeding the following.

Equation 3.3

The total design base shear shall not be less than the following.

Equation 3.4

where, V = total design lateral force or shear as at the base

W = total seismic dead load

Cv = seismic response coefficient represents acceleration response

at 1.0 sec. period

Ca = seismic response coefficient represents effective peak acceleration

at grade

RTICV v

= W

WR

IC5.2V a=

IWC11.0V a=

18

I = important factor depends on occupancy categories

According to UBC (1997), for all buildings, the value of T may be computed

from the following:

Equation 3.5 ¾)= nt

where, T = elastic fundamental period of vibration, in seconds, of the structures

in the direction under consideration

hn = height of structure in feet above base level

Ct = 0.035 for steel moment resisting-frames

Ct = 0.030 for reinforced concrete moment resisting-frames and

eccentrically braced frames

Ct = 0.020 for all other buildings

2. Distribution of total base shear UBC (1997)

In deciding on an appropriate distribution for the horizontal load, the

following factors are considered.

(a) the effective load at a floor level is equal to the product of the mass assigned

to that floor and the horizontal acceleration at that level.

(b) the maximum acceleration at any level of the structure in the fundamental

mode is proportional to its horizontal displacement in that mode.

(c) the fundamental mode for regular structure, consisting of shear walls and

frames, is approximately linear from the base.

The total design base shear, V, is distributed over the height of the structure in

conformance with Equations 3.6, 3.7, 3.8 and distributed according to Figure 3.1.

Equation 3.6 ∑=

h(CT

n

1iit F FV

=

+

where, Ft = concentrated force applied at the top of the structure

Ft = 0.7 TV ≤ 0.25 V for T > 0.7 sec Equation 3.7

Ft = 0 for T ≤ 0.7 sec

The remaining portion of the base shear is distributed over the height of the

structure, including top level, n, according to the expression

Equation 3.8 t x x

x n

i ii 1

(V-F ) w hF w h

=

=

∑

19

where, wi, wx = portion of W located at or assigned to level i or x respectively

hi, hx = height above the base to level i or x respectively

The storey shear, Vx, at any storey, is the sum of the top force, Ft, and the

forces Fx, above that storey.

Equation 3.9 n

x t xi x

where, Vx = design storey shear in storey x

Ft = top force

Fx = design seismic force applied to level x

Data for earthquake loading are as follows:

Seismic Zone = 2A

Zone Factor, Z = 0.15

Structural System = Ordinary Moment-Resisting Frame

Soil Type = SD

Importance Factor, I = 1

Response Modification Factor, R = 3.5

Ct (Reinforced Concrete Frame) = 0.030

Seismic Coefficient, Ca = 0.22

Seismic Coefficient, Cv = 0.32

Figure 3.1. Vertical Distribution of Design Base Shear

Source: Structures and Codes Institute

V F F=

= + ∑

20

3.2.3. Load Combinations

According to ACI 318-99, the 26 design load combinations, which used in this

study, are as follows:

1. COMB1 1.4 D.L

2. COMB2 1.4 D.L + 1.7 L.L

3. COMB3 1.05 D.L + 1.275 L.L + 1.275 WINX

4. COMB4 1.05 D.L + 1.275 L.L - 1.275 WINX

5. COMB5 1.05 D.L + 1.275 L.L + 1.275 WINY

6. COMB6 1.05 D.L + 1.275 L.L - 1.275 WINY

7. COMB7 0.9 D.L + 1.3 WINX

8. COMB8 0.9 D.L - 1.3 WINX

9. COMB9 0.9 D.L + 1.3 WINY

10. COMB10 0.9 D.L - 1.3 WINY

11. COMB11 1.05 D.L + 1.28 L.L + EQX

12. COMB12 1.05 D.L + 1.28 L.L - EQX

13. COMB13 1.05 D.L + 1.28 L.L + EQY

14. COMB14 1.05 D.L + 1.28 L.L - EQY

15. COMB15 0.9 D.L + 1.02 EQX

16. COMB16 0.9 D.L - 1.02 EQX

17. COMB17 0.9 D.L + 1.02 EQY

18. COMB18 0.9 D.L - 1.02 EQY

19. COMB19 1.16 D.L + 1.28 L.L + EQX

20. COMB20 1.16 D.L + 1.28 L.L - EQX

21. COMB21 1.16 D.L + 1.28 L.L + EQY

22. COMB22 1.16 D.L + 1.28 L.L - EQY

23. COMB23 0.79 D.L + 1.02 EQX

24. COMB24 0.79 D.L - 1.02 EQX

25. COMB25 0.79 D.L + 1.02 EQY

26. COMB26 0.79 D.L - 1.02 EQY

To know the performance of the ordinary moment-resisting frame, 18

unfactored load combinations were also considered.

1. UCOMB1 D.L

2. UCOMB2 D.L + L.L

21

3. UCOMB3 D.L + L.L + WINX

4. UCOMB4 D.L + L.L - WINX

5. UCOMB5 D.L + L.L + WINY

6. UCOMB6 D.L + L.L - WINY

7. UCOMB7 D.L + WINX

8. UCOMB8 D.L - WINX

9. UCOMB9 D.L + WINY

10. UCOMB10 D.L - WINY

11. UCOMB11 D.L + L.L + EQX

12. UCOMB12 D.L + L.L - EQX

13. UCOMB13 D.L + L.L + EQY

14. UCOMB14 D.L + L.L - EQY

15. UCOMB15 D.L + EQX

16. UCOMB16 D.L - EQX

17. UCOMB17 D.L + EQY

18. UCOMB18 D.L - EQY

where, D.L = dead load

L.L = live load

WINX = wind load in x direction

WINY = wind load in y direction

EQX = earthquake load in x direction

EQY = earthquake load in y direction

In this study, 10 load combinations (COMB1 to COMB 10) were considered

for without seismic effect. With seismic effect, 26 load combinations (COMB1 to

COMB 26) were considered.

3.3. Grouping of Structural Components

For analysis and design purposes, members were divided into groups of

similar behaviour. For columns, there were three groups; corner, end and interior in

each storey. For beams, there were also three groups, edge, cantilever and interior.

22

3.4. Analysing

After applying loads on structure, models were ready to analyse. Linear static

analysis was performed in this study.

3.5. Analysis Output

3.5.1. Analysis Results for Columns

When analysis was finished, the frame forces for each column specified in

modeling mode were obtained. The column forces are axial force, bending moment in

x-direction and y-direction. These results were collected to excel spreadsheets and

extracted maximum values. With these results the graphs were drawn. Moreover,

compare the results for the ordinary moment-resisting frame without and with seismic

effects.

3.5.2. Analysis Results for Beams

Same as columns, the beam forces were obtained in analysis output mode.

These results were collected to excel and compared the maximum value at the critical

sections of the beams.

3.5.3. Analysis Results for Storey Displacements, Storey Drifts and Storey Shear

Displacements, storey drifts and storey shear were obtained from ETABS

software and collected to excel and then made the comparison of results.

3.6. Concrete Frame Design

In the design of concrete frame, in general, the program calculates and reports

the required areas of steel for flexure and shear based on the axial force, bending

moments, shear, load combination factors and other criteria.

CHAPTER 4

COMPARISON OF RESULTS

4.1. General

Effects of earthquake loads on ordinary moment-resisting frame were

compared using the results of analysis and design. First of all, the analysis results

were compared. The items that are considered in the comparison are column and

beam forces, storey displacement, storey drifts and storey shear.

The axial force, bending moments for x-direction and y-direction are

considered for columns. Also for beams, bending moments, shear and torsional

moment are considered.

4.2. Comparison of Storey Drifts

Comparison of storey drifts were considered the points at which the junction

of beam and column. Among these points, the maximum drifts occurred were

compared in this study.

Comparison of storey drifts without seismic and with seismic are shown in

Table 4.1, Figure 4.1 and Figure 4.2.

Discussions on comparison are presented in section 4.8 of this study.

Drift X Drift Y Storey Height

(ft.) Without EQ EQX Difference

(%) Without

EQ EQY Difference (%)

Drift Limit

(0.02h) Roof 11 0.0924 1.2230 1224 0.1735 0.9883 470 2.6400 11F 11 0.1428 1.5158 961 0.1896 1.4666 673 2.6400 10F 11 0.2038 1.9708 867 0.2264 2.0200 792 2.6400 9F 11 0.2281 2.0977 820 0.2313 2.1482 829 2.6400 8F 11 0.2494 2.2111 787 0.2430 2.2631 831 2.6400 7F 11 0.2712 2.3211 756 0.2626 2.4196 821 2.6400 6F 11 0.2989 2.4637 724 0.2766 2.5088 807 2.6400 5F 11 0.3212 2.5360 690 0.2911 2.5980 793 2.6400 5F 11 0.3212 2.5360 690 0.2911 2.5980 793 2.6400

Table 4.1. Comparison of Storey Drifts without Earthquake and with Earthquake

24

Drift X Drift Y Storey Height

(ft.) Without EQ EQX Difference

(%) Without

EQ EQY Difference (%)

Table 4.1. - Continued Drift Limit

(0.02h) 4F 11 0.3342 2.5164 653 0.3006 2.6455 780 2.6400 3F 11 0.3312 2.3807 619 0.2996 2.6112 771 2.6400 2F 14 0.4141 2.8565 590 0.3761 3.2536 765 3.3600 1F 14 0.3330 2.2393 573 0.3011 2.5872 759 3.3600 G F 10 0.0995 0.6622 566 0.0897 0.7678 756 2.4000 Base 0 0.0000 0.0000 0 0.0000 0.0000 0 0.0000

Storey Drift -X Comparison

0.0

1.0

2.0

3.0

4.0

Bas

e

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Drif

t X (i

n.)

without EQwith EQDrift Limit

Figure 4.1. Comparison of Storey Drift in X Direction without Earthquake and with

Earthquake

Storey Drift-Y Comparison

0.0

1.0

2.0

3.0

4.0

Bas

e

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Drif

t Y (i

n.)

without EQwith EQDrift Limit

Figure 4.2. Comparison of Storey Drift in Y Direction without Earthquake and with

Earthquake

25

4.3. Comparison of Storey Displacements

Comparison of storey displacements was considered the points at which the

maximum the displacement occurred. Comparison of storey displacements without

seismic and with seismic are shown in Table 4.2, Figure 4.3 and Figure 4.4.


Table 4.2. Comparison of Storey Displacements without Earthquake and with

Earthquake Displacement, Ux Displacement, Uy

Storey Height (ft.) Without

EQ EQX Difference (%)

Without EQ EQY Difference

(%) Roof 11 1.3550 11.0181 713 1.3311 11.5420 767 11F 11 1.3173 10.5189 699 1.2603 11.1386 784 10F 11 1.2590 9.9002 686 1.1829 10.5400 791 9F 11 1.1758 9.0958 674 1.0905 9.7155 791 8F 11 1.0827 8.2396 661 0.9961 8.8387 787 7F 11 0.9809 7.3371 648 0.8969 7.9150 782 6F 11 0.8702 6.3897 634 0.7897 6.9274 777 5F 11 0.7482 5.3841 620 0.6768 5.9034 772 4F 11 0.6171 4.3490 605 0.5580 4.8430 768 3F 11 0.4807 3.3219 591 0.4353 3.7632 765 2F 14 0.3455 2.3502 580 0.3130 2.6974 762 1F 14 0.1765 1.1843 571 0.1595 1.3694 759 G F 10 0.0406 0.2703 566 0.0366 0.3134 756 Base 0 0.0000 0.0000 0 0.0000 0.0000 0

Storey Displacement, Ux Comparison

0.0

2.0

4.0

6.0

8.0

10.0

12.0

Bas

e

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Ux

(in.)

without EQwith EQ

Figure 4.3. Comparison of Storey Displacement - Ux without Earthquake and

with Earthquake

26

Storey Displacement,Uy Comparison

0.0

2.0

4.0

6.0

8.0

10.0

12.0

Bas

e

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Uy (

in.)

without EQwith EQ

Figure 4.4. Comparison of Storey Displacement - Uy without Earthquake and with

Earthquake

4.4. Comparison of Storey Shear

Comparison of storey shear without seismic and with seismic for each storey

are shown in Table 4.3, Figure 4.5 and Figure 4.6.


Table 4.3. Comparison of Storey Shear without Earthquake and with Earthquake

Vx (kips) Vy (kips) Storey Without

EQ EQX Difference (%)

Without EQ EQY Difference

(%) RF 34 326.6 861 37.4 326.6 773

11.F 62.8 602.3 859 67.1 602.3 798 10.F 94.7 890.9 841 95.4 890.9 834 9.F 126.6 1156.9 814 123.7 1156.9 835 8.F 157.5 1400.6 789 151.1 1400.6 827 7.F 188.3 1622.0 761 178.4 1622.0 809 6.F 217.8 1820.5 736 204.5 1820.5 790 5.F 247.2 1995.2 707 230.7 1995.2 765 4.F 275.3 2145.1 679 255.6 2145.1 739 3.F 301.7 2269.2 652 279 2269.2 713 2.F 334.9 2392.6 614 309.2 2392.6 674 1.F 372.5 2468.2 563 344 2468.2 618

G.F 391.3 2485.7 535 361.5 2485.7 588

27

Storey Shear Vx Comparison

0

500

1000

1500

2000

2500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Vx (

kips

)

without EQwith EQ

Figure 4.5. Comparison of Storey Shear - Vx without Earthquake and with Earthquake

Storey Shear Vy Comparison

0

500

1000

1500

2000

2500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

Vy (

kips

)

without EQwith EQ

Figure 4.6. Comparison of Storey Shear -Vy without Earthquake and with Earthquake

4.5. Comparison of Critical Forces in Columns

Comparison of critical forces in columns includes axial force and bending

moments in two directions without seismic and with seismic effects for three groups

of column.


28

4.5.1. Comparison of Axial Force for Columns

Comparison axial force for column includes corner, end and interior columns.

4.5.1.1. Comparison of axial force for corner column

Comparisons of axial forces for corner columns are shown in Figure 4.7 to

Figure 4.9.

Axial Force Comparison for Corner Column - C70

0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Axi

al F

orce

(kip

s)

wo EQwith EQ (factored)

with EQ (unfactored)

Figure 4.7. Comparison of Axial Force for Corner Column, C70, between without

Earthquake, with Earthquake (factored load) and with Earthquake

(unfactored load)


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Axi

al F

orce

(kip

s)

wo EQwith EQ (factored)with EQ (unfactored)



(unfactored load)

29

Axial Force Comparison for End Column - C55

0

200

400

600

800

1000

1200

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Axi

al F

orce

(kip

s)



4.5.1.2. Comparison of axial force for end column

Comparisons of axial forces for end columns are shown in Figure 4.10 to

Figure 4.11.

0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Axi

al F

orce

(kip

s)




(unfactored load)

Figure 4.10. Comparison of Axial Force for End Column, C55, between without


(unfactored load)

30

4.5.1.3. Comparison of axial force for interior column

Comparisons of axial forces for end columns are shown in Figure 4.12 to

Figure 4.19.

Figure 4.11. Comparison of Axial Force for End Column, C69, between without


(unfactored load)

Figure 4.12. Comparison of Axial Force for Interior Column, C42, between without


(unfactored load)

Axial Force Comparison for Interior Column - C42

0

200

400

600

800

1000

1200

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

rk

Axi

al F

oce

(ip

s

without EQwith EQ (factored)with EQ (unfactored)

Axial Force Comparison for End Column - C69

0

200

400

600

800

1000

1200

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

o (

ski

prc

eia

l FA

x


31


0

200

400

600

800

1000

1200

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

As

cip

e (k

For

xial




(unfactored load)


0

300

600

900

1200

1500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

Aip

se

(kl F

cor

xia




(unfactored load)

32


0

400

800

1200

1600

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

s (k

ipia

l For

cex

A




(unfactored load)


0

300

600

900

1200

1500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

As

l Fip

e (k

orc

xia




(unfactored load)

33


0

300

600

900

1200

1500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

xs

(kip

ial F

orce

A




(unfactored load)


0

300

600

900

1200

1500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

sl F

eip

(kor

cxi

aA




(unfactored load)

34


0

300

600

900

1200

1500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

iar

ips)

ce (k

l Fo

Ax


4.5.2. Comparison of Bending Moment in X Direction for Columns

Comparison bending moments for column includes corner, end and interior

columns.



(unfactored load)

4.5.2.1. Comparison of bending moments in x direction for corner column

Comparisons of bending moments in x direction for corner columns are shown

in Figure 4.20 to Figure 4.22.

M3 Comparison for Corner Column - C70

0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

3ps

-ft)

(ki

M


Figure 4.20. Comparison of Bending Moment in X Direction for Corner Column,

C70, between without Earthquake, with Earthquake (factored load) and

with Earthquake (unfactored load)

35


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

-ft)

ips

(kM

3






0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

s-ft)

(kip

M3





36

4.5.2.2. Comparison of bending moments in x direction for end column

Comparisons of bending moments in x direction for end columns are shown in

Figure 4.23 to Figure 4.24.

M3 Comparison for End Column - C55

0

200

400

600

800

1000G

roun

d

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

-ft)

(kip

sM

3


Figure 4.23. Comparison of Bending Moment in X Direction for End Column,C55,

between without Earthquake, with Earthquake (factored load) and with

Earthquake (unfactored load)


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

M3

(kip

s-ft)


Figure 4.24. Comparison of Bending Moment in X Direction for End Column,C69,



37

4.5.2.3. Comparison of bending moments in x direction for interior column

Comparisons of bending moments in x direction for interior columns are

shown in Figure 4.25 to Figure 4.32.

M3 Comparison for Interior Column - C42

0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

M-f

t)ip

s3

(k


Figure 4.25. Comparison of Bending Moment in X Direction for Interior Column,




0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

s-ft)

(kip

M3





38


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

(k-f

t)ip

sM

3






0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

s-ft)




M3

p (k

i


39


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

(k-ft

)ip

sM

3






0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

-ft)

s (k

ipM

3





40


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

(k-f

t)ip

sM

3






0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

s-ft)




M3

p (k

i


41

4.5.3. Comparison of Bending Moment in Y Direction for Columns

Comparison bending moments for column includes corner, end and interior

columns.

4.5.3.1. Comparison of bending moments in y direction for corner column

Comparisons of bending moments in y direction for corner columns are shown

in Figure 4.33 to Figure 4.35.


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

ps-ft

)2

(ki

M


Figure 4.33. Comparison of Bending Moment in Y Direction for Corner Column,




0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s-ft)

p2

(ki

M





42


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

4.5.3.2. Comparison of bending moments in y direction for end column

Comparisons of bending moments in y direction for end columns are shown in





Figure 4.36. Comparison of Bending Moment in Y Direction for End Column, C55,

between without Earthquake, with Earthquake (factored load) and


M2

(kip

s-ft)



0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

Mip

s-ft)

2 (k


43


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

(k-f

t)ip

sM

2


Figure 4.37. Comparison of Bending Moment in Y Direction for End Column,C69,



4.5.3.3. Comparison of bending moments in y direction for interior column

Comparisons of bending moments in y direction for end columns are shown in



0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

M-f

t)ip

s2

(k


Figure 4.38. Comparison of Bending Moment in Y Direction for Interior Column,



44


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

(k-f

t)ip

sM

2






0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

s-ft)

(kip

M2





45


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

(k-f

t)ip

sM

2






0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

s-ft)

(kip

M2





46


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

(k-f

t)ip

sM

2






0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor




M2

(kip

s-ft)


47


0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

s-ft)

4.6. Comparison of Critical Forces in Beams

Comparison of critical forces in beams includes shear force, torsion and

bending moments in at support and mid span without seismic and with seismic effects

for three groups of beams.


4.6.1. Comparison of Shear Force for Beams

Comparison shear force for beams includes edge, cantilever and interior

beams.

4.6.1.1. Comparison of shear force for edge beams

Comparisons of shear force for edge beams are shown in Figure 4.46 to

Figure 4.49.




M2

p (k

i


48

Shear Force Comparison for Edge Beam - B10

0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

oki

ps)

rce

(ea

r FSh


Figure 4.46. Comparison of Shear Force for Edge Beam - B10, between without


(unfactored load)


0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s) F

ce (

pki

orhe

arS


Figure 4.47. Comparison of Shear Force for Edge Beam – B77, between without


(unfactored load)

49


0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Shea

r For

ce (k

ips)




(unfactored load)


0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

hs)

kip

orce

(ea

r FS




(unfactored load)

50

4.6.1.2. Comparison of shear force for cantilever beams

Comparisons of shear force for cantilever beams are shown in Figure 4.50 to

Figure 4.53.

Shear Force Comparison for Cantilever Beam - B270

0

5

10

15

20

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

ear

o

Figure 4.50. Comparison of Shear Force for Cantilever Beam B270, between without


(unfactored load)

Figure 4.51. Comparison of Shear Force for Cantilever Beam B273, between

without Earthquake, with Earthquake (factored load) and with


Sh F

rce

(kip

s)


Shear Force Comparison for Cantilever Beam - B273

0

5

10

15

20

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

h F

ce (

ps)

kior

ear

S


51

Shear Force Comparison for Cantilever Edge Beam - B169

0

5

10

15

20

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

h F

ce (

ps)

kior

ear

S


Figure 4.52. Comparison of Shear Force for Cantilever Edge Beam B169, between



Shear Force Comparison for Cantilever Edge Beam - B166

0

5

10

15

20

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

ips)

Figure 4.53. Comparison of Shear Force for Cantilever Edge Beam B166, between



Shea

r For

ce (k


52

4.6.1.3. Comparison of shear force for interior beams

Comparisons of shear force for interior beams are shown in Figure 4.54 to

Figure 4.62.

Shear Force Comparison for Interior Beam - B12

0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

)ki

psor

ce (

ear F

Sh


Figure 4.54. Comparison of Shear Force for Interior Beam B12, between without


(unfactored load)


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

kips

)or

ce (

ear F

Sh




(unfactored load)

53


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

hs)

orce

(kip

ear F

S




(unfactored load)


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s) F

ce (k

ipor

hear

S




(unfactored load)

54


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor



(unfactored load)



(unfactored load)

She

o(k

ips)

rce

ar F



0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

hs)

kip

orce

(ea

r FS


55


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

kips

)rc

e (

oea

r FSh




(unfactored load)


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

kips

)or

ce (

ear F

Sh




(unfactored load)

56


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

S F

ce (

s)ki

por

hear




(unfactored load)

4.6.2. Comparison of Torsion for Beams

Comparison of torsion for beams includes edge, cantilever and interior beams.

4.6.2.1. Comparison of torsion for edge beams

Comparisons of torsion for edge beams are shown in Figure 4.63 to Figure

4.66.

Torsion Comparison for Edge Beam - B10

0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

rs (k

-ft)

ips

ion

To


Figure 4.63. Comparison of Torsion for Edge Beam B10, between without


(unfactored load)

57


0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor



(unfactored load)



(unfactored load)

Tors

ion

s-ft)

(kip



0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Tors

ion

(kip

s-ft)


58


0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

rs

4.6.2.2. Comparison of torsion for cantilever beams

Comparisons of torsion for cantilever beams are shown in Figure 4.67 to

Figure 4.70.



(unfactored load)

Figure 4.67. Comparison of Torsion for Cantilever Beam B270, between without


(unfactored load)

Toio

n (k

ips-

ft)


Torsion Comparison for Cantilever Beam - B270

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

tTo

ips-

fn

(krs

io


59

Torsion Comparison for Cantilever Beam - B273

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

on

(kip

s-ft

rsio

T


Figure 4.68. Comparison of Torsion for Cantilever Beam B273, between without


(unfactored load)

Torsion Comparison for Cantilever Edge Beam - B169

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

To

ftip

s-n

(kor

si


Figure 4.69. Comparison of Torsion for Cantilever Edge Beam B169, between



60

Torsion Comparison for Cantilever Edge Beam - B166

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

it

ps-f

n (k

Tors

io


4.6.2.3. Comparison of torsion for interior beams

Comparisons of torsion for interior beams are shown in Figure 4.71 to

Figure 4.79.

Figure 4.70. Comparison of Torsion for Cantilever Edge Beam B166, between



Torsion Comparison for Interior Beam - B12

0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Figure 4.71. Comparison of Torsion for Interior Beam B12, between without


(unfactored load)

Tors

ion

(kip

s-ft)


61


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor



(unfactored load)



(unfactored load)

Tors

ion

(kip

s-ft)



0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Tors

ioip

s-ft)

n (k


62


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s-ft)



(unfactored load)



(unfactored load)

Tors

ion

(kip



0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

oi

)ps

-ft

n (k

Tors

i


63


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s-ft)



(unfactored load)



(unfactored load)

Tors

ion

(kip



0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

oip

s-ft)

n (k

Tors

i


64


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s-ft)



(unfactored load)



(unfactored load)

Tors

ion

(kip



0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

To)

rsio

n (k

ips-

ft


65

4.6.3. Comparison of Bending Moment at Support for Beams

Comparison Bending Moment at Support for beams includes edge, cantilever

and interior beams.

4.6.3.1. Comparison of bending moment at support for edge beams

Comparisons of bending moment at support for edge beams are shown in


Bending Moment at Support Comparison for Edge Beam - B10

0

50

100

150

200

250

300

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

(k-ft

)ip

sM

3


Figure 4.80. Comparison of Bending Moment at Support for Edge Beam B10,




0

50

100

150

200

250

300

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

kft)

ips-

M3

(





66


0

50

100

150

200

250

300

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor







M3

(kip

s-ft)



0

50

100

150

200

250

300

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

M3

(kip

s-ft)


67

4.6.3.2. Comparison of bending moment at support for cantilever beams

Comparisons of bending moment at support for cantilever beams are shown in


Bending Moment at Support Comparison for Cantilever Beam - B270

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

)ip

s-ft

M3

(k


Figure 4.84. Comparison of Bending Moment at Support for Cantilever Beam B270,



Bending Moment at Support Comparison for Cantilever Beam - B273

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

3ps

-ft)

(ki

M


Figure 4.85. Comparison of Bending Moment at Support for Cantilever Beam B273,



68

Bending Moment at Support Comparison for Cantilever Edge Beam - B169

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

-ft)

ips

(kM

3


Figure 4.86. Comparison of Bending Moment at Support for Cantilever Edge Beam

B169, between without Earthquake, with Earthquake (factored load) and


Bending Moment at Support Comparison for Cantilever Edge Beam - B166

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s-ft)

(kip

M3


Figure 4.87. Comparison of Bending Moment at Support for Cantilever Edge Beam

B166, between without Earthquake, with Earthquake (factored load) and


69

4.6.3.3. Comparison of bending moment at support for interior beams

Comparisons of bending moment at support for interior beams are shown in


Bending Moment at Support Comparison for Interior Beam - B12

0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

(k-f

t)ip

sM

3


Figure 4.88. Comparison of Bending Moment at Support for Interior Beam B12,




0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

3ps

-ft)

(ki

M





70


0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

(kip

s-ft)

M3






0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

p)

s-ft

M3

(ki





71


0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor







M3

(kip

s-ft)



0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

3ps

-ft)

(ki

M


72


0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor







M3

(kip

s-ft)



0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

M3

(kip

s-ft)


73


0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

)M

3 (k

ips-

ft


4.6.4. Comparison of Bending Moment at Midspan for Beams

Comparison Bending Moment at midspan for beams includes edge, cantilever

and interior beams.




4.6.4.1. Comparison of bending moment at midspan for edge beams

Comparisons of bending moment at midspan for edge beams are shown in


Bending Moment at Midspan Comparison for Edge Beam - B10

0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

M3

(kip

s-ft)


Figure 4.97. Comparison of Bending Moment at Midspan for Edge Beam B10,



74


0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

(kip

s-ft)

M3






0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor




M3

(kip

s-ft)


75


0

25

50

75

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

4.6.4.2. Comparison of bending moment at midspan for cantilever edge beams

Comparisons of bending moment at midspan for cantilever edge beams are

shown in Figure 4.101 to Figure 4.102.




Figure 4.101. Comparison of Bending Moment at Midspan for Cantilever Edge

Beam B169, between without Earthquake, with Earthquake (factored

load) and with Earthquake (unfactored load)

M3

(k-f

t)ip

s


Bending Moment at Midspan Comparison for Cantilever Edge Beam - B169

0

5

10

15

20

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

-ft)

M3

(kip

s


76

Bending Moment at Midspan Comparison for Cantilever Edge Beam - B166

0

5

10

15

20

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

M-f

t)ip

s3

(k


Figure 4.102. Comparison of Bending Moment at Midspan for Cantilever Edge

Beam B166, between without Earthquake, with Earthquake (factored

load) and with Earthquake (unfactored load)

4.6.4.3. Comparison of bending moment at midspan for interior beams

Comparisons of bending moment at midspan for interior beams are shown in


Bending Moment at Midspan Comparison for Interior Beam - B12

0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

-ft)

M3

(kip

s


Figure 4.103. Comparison of Bending Moment at Midspan for Interior Beam B12,



77


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

(kip

s-ft)

M3






0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor




M3

(kip

s-ft)


78


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

(-f

t)ki

psM

3






0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s-ft)

p (k

iM

3





79


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

(kip

s-ft)

M3






0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

) (k

ips-

ftM

3





80


0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

s-ft)

M3

(kip






0

20

40

60

80

100

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor




M3

(kip

s-ft)


81

4.7. Comparison of Critical Forces for One Panel Continuous Beam-Column

Frame

Comparisons of critical forces for columns and beams, which are continuous

frame in choosing one panel, are shown in the following Figure 4.112 to Figure 4.118

and Table 4.4 to Table 4.10.


4.7.1. Comparison of Critical Force Differences for Column

Comparison of critical force differences for columns from one panel

continuous beam-column frame are shown in Figure 4.112 to Figure 4.114.

Compariosn of Axial Force Differences for Columns

0

10

20

30

40

50

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

Diff

eren

ces (

%)

C54 C41

Figure 4.112. Comparison of Axial Force Differences for Columns from One Panel

Continuous Beam-Column Frame

Figure 4.113. Comparison of Bending Moment in X Direction Differences for

Columns from One Panel Continuous Beam-Column Frame

C55 C42

Compariosn of Bending Moment in X Direction Differences for Columns

0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Diff

eren

ces (

%)

C54 C41

C55 C42

82

Compariosn of Bending Moment in Y Direction Differences for Columns

0

200

400

600

800

1000

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roo

f

Floor

Diff

eren

ces (

%)

C54 C41

C55 C42

Figure 4.114. Comparison of Bending Moment in Y Direction Differences for

Columns from One Panel Continuous Beam-Column Frame

4.7.2. Comparison of Critical Force Differences for Beams

Comparison of critical force differences for beams from one panel continuous

beam-column frame are shown in Figure 4.115 to Figure 4.118.

Comparison of Torsion Differences for Beams

0

200

400

600

800

1000

1200

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

Diff

eren

ces (

%)

B11 B60

Figure 4.115. Comparison of Shear Force Differences for Beams from One Panel


B51 B10

83

Comparison of Torsion Differences for Beams

0

200

400

600

800

1000

1200

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

Diff

eren

ces (

%)

B11 B60

B51 B10

Figure 4.116. Comparison of Torsion Differences for Beams from One Panel


Comparison of Bending Moment at Support Differences for Beams

0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

Diff

eren

ces (

%)

B11 B60

B51 B10

Figure 4.117. Comparison of Bending Moment at Support Differences for Beams

from One Panel Continuous Beam-Column Frame

84

Comparison of Bending Moment at Midspan Differences for Beams

0

100

200

300

400

500

Gro

und

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

Roof

Floor

Diff

eren

ces (

%)

B11 B60

B51 B10

Figure 4.118. Comparison of Bending Moment at Midspan Differences for Beams

from One Panel Continuous Beam-Column Frame

85

Table 4.4.

86

Table 4.5.

87

Table 4.6.

88

Table 4.7.

89

Table 4.8.

90

Table 4.9.

91

Table 4.10.

92

4.8. Discussions on Comparisons

The comparisons of responses and critical forces of structure are shown in

above articles by graphically without and with seismic effects for factored and

unfactored load conditions. Detailed discussions are described in below with referred

to those above comparison graphs.

4.8.1. Comparison of Storey Drifts

It is inevitable that tall buildings subjected to earthquake are more or less

prone to sway which is technically defined as drift. This drift tends to create failure of

member and deteriorate comfort of the occupants.

From the comparison of results, storey drifts due to without seismic effect is

increased to minimum of 470 percent and maximum of 1224 percent when considered

with seismic effect. Although the storey drifts in the case study building are increased

due to earthquake loads, most of them are still below the allowable limits. But only

one floor, 4th floor (52 feet above ground level), exceeds the allowable limit about

0.21 percent.

4.8.2. Comparison of Storey Displacements

From Table 4.2, Figure 4.3 and Figure 4.4, comparative study for the

differences of storey displacements is as follow:

Storey displacement due to without seismic force is increased to minimum of

566 percent and maximum of 791 percent when considered with seismic effects.

4.8.3. Comparison of Storey Shear

From Table 4.3, Figure 4.5 and Figure 4.6, the storey shear due to without

seismic force is increased to minimum of 535 percent and maximum of 861 percent

when considered with seismic effects.

4.8.4. Comparison of Columns

Comparison of columns includes axial force, bending moment in x and y

directions without seismic and with seismic effects for three groups of column.

4.8.4.1. Axial force

For corner columns, axial forces due to seismic effect under zone 2A are

93

increased to minimum one percent and maximum 28 percent for factored load

conditions. Axial force increments are high at the middle floors.

For end columns, axial force due to seismic forces is minimum one percent

and maximum eight percent higher than that of without seismic forces for factored

load conditions. For unfactored load conditions, axial force is not increased in these

columns.

For interior columns, axial forces without and with seismic effects are not

different for factored load conditions.

4.8.4.2. Bending moment in x direction

For corner columns, bending moment in x direction without seismic effects is

increased to minimum nine percent and maximum 671 percent when considered with

seismic effects under zone 2A for factored load conditions. For these columns,

increment is high at the bottom storeys.

For end columns, bending moment in x direction without seismic effects is

increased to minimum 32 percent and maximum 603 percent when considered with

seismic effects under zone 2A for factored load conditions.

For interior columns, bending moment in x direction without seismic effects is



From the comparison graphs, the shapes of moment increment curves are

similar for both factored and unfactored load conditions.

4.8.4.3. Bending moment in y direction

For corner columns, bending moment in y direction without seismic effects is


seismic effects under zone 2A for factored load conditions. For these columns,

increment is high at the bottom storeys.

For end columns, bending moment in y direction without seismic effects is



For interior columns, bending moment in y direction without seismic effects is



94

From the comparison graphs, the shapes of moment increment curves are

similar for both factored and unfactored load conditions.

4.8.5. Comparison of Beams

Comparison of beams includes shear force, torsional moment, bending at

support and midspan without seismic and with seismic effects for three groups of

beams.

.

4.8.5.1. Shear force

For edge beams, shear force without seismic effects is increased to minimum

one percent and maximum 403 percent when considered the seismic effects for

factored load conditions. For these beams, increased percentage is high at the middle

storeys and low at the top storeys.

For cantilever beams, shear force without seismic effects is increased to

minimum one percent and maximum seven percent when considered the seismic

effects. Also for cantilever edge beams, shear force increased to minimum three

percent and maximum 69 percent when considered the seismic effects.

For interior beams, shear force without seismic effects is increased to

minimum one percent and maximum 226 percent when considered the seismic effects

for factored load conditions. For these beams, shear increment percent is high at the

middle storeys.

4.8.5.2. Torsion

For edge beams, torsion without seismic effects is increased to minimum 14

percent and maximum 445 percent when considered the seismic effects under zone

2A for factored load conditions.

For cantilever beams, torsion without seismic effects is increased to minimum

74 percent and maximum 492 percent when considered the seismic effects. For these

beams, torsion increment is high at the middle storeys. From the comparison graph,

torsion curve is gradually decreased to top storeys. Also for cantilever edge beams,

torsion increased to minimum 18 percent and maximum 375 percent when considered

the seismic effects. For these beams, increment percentage is high, but the magnitude

of torsion without and with seismic are not so large.

For interior beams, torsion without seismic effects is increased to minimum 16

95

percent and maximum 686 percent when considered the seismic effects for factored

load conditions. For these beams, torsion increment percentage is high at the middle

storeys.

From the comparison graph, torsion with seismic effects for unfactored load

conditions curve lied close to the factored load conditions for all of the beams

mentioned above.

4.8.5.3. Bending moment at support

For edge beams, negative bending moment at support without seismic effects

is increased to minimum 25 percent at the top storeys and maximum 509 percent at

the middle storeys when considered the seismic effects under zone 2A for factored

load conditions. Positive bending moment at support without seismic effects is

increased mostly at the middle storeys and increased percentage is high in these

storeys.

For cantilever beams, negative bending moments at support without seismic

effects are not different when considered the seismic effects for factored load

conditions. Also for cantilever edge beams, negative bending moment at support is

increased to minimum 22 percent and maximum 245 percent when considered the

seismic effects.

For interior beams, negative bending moment at support without seismic

effects is increased to minimum 17 percent and maximum 365 percent when

considered the seismic effects under zone 2A for factored load conditions. From

comparison graph, negative bending moment at support increment percentage is high

at the middle storeys. Positive bending moment at support without seismic effects is

increased mostly at the middle storeys and percent increment is high in these storeys.

4.8.5.4. Bending moment at midspan

For edge beams, positive bending moment at midspan without seismic effects

is not different when considered the seismic effects under zone 2A for factored load

conditions except for ground floor beams.

For cantilever edge beams, positive bending moments at midspan without

seismic effects is increased to minimum two percent and maximum 30 percent when

considered the seismic effects under zone 2A for factored load conditions.

For interior beams, positive bending moments at midspan without and with

96

seismic effects under zone 2A are nor different for factored load conditions except for

ground floor beams. For ground floor beams, bending moment at midspan increased

to minimum 177 percent and maximum 350 percent when considered seismic for

factored load conditions.

4.8.6. Comparison of Critical Forces for One Panel Continuous Beam-Column Frame

Comparison of critical forces for four columns and four beams in one panel

are important for determining force increments and changing deformation when

subjected to moderate seismic forces.

Axial forces of column are found to increase to maximum 22 percent at the

corner column and also increased to maximum five percent in end column. But axial

forces of interior column are not increased in this one panel continuous beam-column

frame. Bending moments in x direction of columns are increased to minimum 174

percent and maximum 485 percent. Bending moment in y-direction of interior and

end columns are increased to minimum 464 percent and maximum 663 percent at the

lower and middle storeys. Also bending moment in y-direction of corner column

increased to minimum 210 percent and maximum 559 percent at the lower and middle

stories.

Bending moment at support of beams increased to maximum 460 percent at

the middle stories. Bending moments at midspan of beams are not increased except at

the ground floor beams which increased to maximum 270 percent.

Torsion had increased to maximum 441 percent at the middle stories. Shear

force also increased to maximum 200 percent except the ground floor beams. At

ground floor beam, shear force increased about 250 percent.

4.8.7. Summarised Discussions on Comparisons

From the comparative study for the existing building which was designed

without consideration for seismic effects and then subjected to moderate seismic

forces in zone 2A, it was found that the followings:

1. Force increments in the columns are greater than that of in the beams.

2. The most critical force for column is bending moment in this study.

3. The most critical force for beams is bending moment in this study.

4. Most critical forces are found at middle storeys for beams and bottom

storeys for columns.

97

5. Storey drift increments are large but most of the drifts are within the

allowable limit and only one floor exceeds the allowable limit about 0.21

percent.

It is found that the force and force increments are large mostly at the bottom

and middle storeys. Thus initial damage will be begun at the middle and bottom

storeys.

Table 4.4. Comparison of Critical Force for Columns (One Panel) – Axial Force (kips)

Interior Column, C54 Corner Column, C41 End Column, C55 Interior Column, C42 Storey Without

EQ With EQ Diff: (%) Without EQ With EQ Diff: (%) Without

EQ With EQ Diff: (%)

Without EQ With EQ Diff: (%)

Roof 90.8 90.6 0 32.9 33.4 2 60.8 59.7 -2 55.5 55.5 0

11th Floor 197.7 197.4 0 97.8 98.5 1 149.5 148 -1 141.5 141.6 0

10th Floor 302.9 302.6 0 160.6 161.1 0 233.8 232.6 -1 226.1 226.1 0

9th Floor 409.3 409 0 224.3 228.1 2 317.5 316.4 0 310.9 310.9 0

8th Floor 517 516.6 0 287.7 303.4 5 402.4 401.4 0 396.5 396.5 0

7th Floor 625.9 625.6 0 352 384.1 9 488.8 487.9 0 482.2 482.1 0

6th Floor 736.4 736 0 417.6 470.8 13 576.6 578.8 0 568.9 568.8 0

5th Floor 848.3 848 0 482.9 561.5 16 666.5 680.2 2 655.8 655.7 0

4th Floor 961.7 961.4 0 549.5 656.9 20 756.4 782.6 3 744.9 744.8 0

3rd Floor 1074.6 1074.3 0 617.5 753.6 22 848.6 887.7 5 835.9 835.8 0

2nd Floor 1193.5 1193.1 0 709.5 828.9 17 949.3 975.7 3 938.8 938.8 0

1st Floor 1304.3 1303.9 0 811.4 909.5 12 1047.9 1054.3 1 1033.1 1033.1 0

G Floor 1327.4 1327.1 0 830.1 925.6 12 1067.5 1072.1 0 1053 1052.9 0

Table 4.5. Comparison of Critical Force for Columns (One Panel) – Bending Moment in X Direction (kips-ft)





Roof 13.8 53.9 291 23 31.7 38 39.4 51.9 32 17.7 54.2 206

11th Floor 23.5 98.1 317 37.7 68.9 83 32.1 74.3 131 32.4 102.2 215

10th Floor 32.1 142.2 343 30 79.0 163 38 105.4 177 32.3 120.2 272

9th Floor 39.2 186.0 374 39.4 108.0 174 34.2 103.3 202 42.9 157.9 268

8th Floor 43.5 207.1 376 35.8 108.6 203 38.3 118.4 209 53.2 208.8 292

7th Floor 50.1 247.3 394 39.5 121.8 208 41.9 138.3 230 59 232.3 294

6th Floor 54.7 291.7 433 45 138.6 208 43.8 147.8 237 69 272.8 295

5th Floor 60.8 291.7 380 43.8 146.3 234 50 174.9 250 68 279.4 311

4th Floor 70.2 345.5 392 42.5 146.8 245 44.8 157.7 252 73.3 311.4 325

3rd Floor 71.7 340.4 375 84 282.8 237 82.8 296.0 257 94.2 350.0 272

2nd Floor 74.6 390.5 423 69.2 287.8 316 75.8 333.3 340 98.4 366.7 273

1st Floor 97.7 564.9 478 71.2 376.9 429 82.7 454.3 449 90.9 470.5 418

G Floor 138.6 808.2 483 87.9 496.9 465 112.6 627.4 457 111.9 654.3 485

Table 4.6. Comparison of Critical Force for Columns (One Panel) – Bending Moment in Y Direction (kips-ft)





Roof 6.6 54.6 727 17.9 26.3 47 12 48.5 304 10.7 50.8 375

11th Floor 9.1 81.1 791 28.4 58.0 104 16.3 72.3 344 11.9 78.6 561

10th Floor 18.3 141.3 672 23.6 61.2 159 25.2 139.6 454 15.7 91.5 483

9th Floor 25.8 177.3 587 32.7 101.5 210 24.7 147.3 496 23.2 135.3 483

8th Floor 30.9 212.8 589 30.3 100.0 230 29.5 192.7 553 29.3 170.8 483

7th Floor 33.9 231.1 582 34.9 120.7 246 34.7 225.1 549 33.6 195.3 481

6th Floor 38.8 296.0 663 41.6 149.9 260 37 240.4 550 42.1 246.0 484

5th Floor 48.2 296.0 514 39.9 151.0 278 48.5 313.0 545 41.9 242.6 479

4th Floor 54.3 354.4 553 47.6 199.2 318 57.3 364.0 535 49.2 272.1 453

3rd Floor 52.1 318.5 511 60.8 336.6 454 57.7 400.8 595 50.7 303.1 498

2nd Floor 76 428.3 464 40.4 266.1 559 44.5 318.2 615 58.6 332.3 467

1st Floor 101.6 577.9 469 68.1 340.9 401 80.6 401.9 399 84 478.7 470

G Floor 148.4 839.6 466 103.5 456.7 341 137.4 602.3 338 114 647.6 468

Table 4.7. Comparison of Critical Force for Beams (One Panel) – Shear Force (kips)

Interior Beam, B11 Interior Beam, B60 Interior Beam, B51 Edge Beam, B10 Storey Without


Without EQ With EQ Diff: (%) Without

EQ With EQ Diff: (%) Without EQ With EQ Diff: (%)

Roof 22.5 22.4 0 11.6 12.7 9 7.9 10.2 29 10.3 10.4 1

11th Floor 30.2 31.9 6 20.3 26.6 31 17.3 22.6 31 24.5 26.4 8

10th Floor 31.3 36.8 18 18.4 27.9 52 14.9 25.3 70 24.9 30.2 21

9th Floor 31 41 32 18.3 32.4 77 14.9 29.8 100 24.7 33.3 35

8th Floor 30.9 44.3 43 18.3 37.7 106 14.9 33.2 123 24.6 37 50

7th Floor 31 47.8 54 18.1 41.6 130 14.8 37.7 155 24.6 39.9 62

6th Floor 31 50.9 64 18 45.2 151 15.3 41.9 174 24.4 42.4 74

5th Floor 31 53 71 18.3 47.8 161 15.8 46 191 24.5 44.4 81

4th Floor 31 54.3 75 18.9 49.2 160 16.3 48.9 200 24.4 45.9 88

3rd Floor 29.9 54.6 83 19.2 49.3 157 16.3 48.7 199 24.3 46.8 93

2nd Floor 30.8 52.6 71 19.1 47.9 151 16.2 42.8 164 30.1 52.4 74

1st Floor 25.2 44 75 16.9 42.5 151 16.8 37.4 123 26.1 44.3 70

G Floor 4.5 16 256 4.5 19.2 327 4.7 16.8 257 4.6 16.2 252

Table 4.8. Comparison of Critical Force for Beams (One Panel) – Torsion (kips-ft)





Roof 7.2 11.2 56 1.2 2.5 108 1.7 3.1 82 8.4 9.6 14

11th Floor 2.9 11.2 286 7.7 13.5 75 4 7.1 78 12.9 18.3 42

10th Floor 6.7 23.5 251 6.5 16.1 148 3.8 9.5 150 12.6 23.6 87

9th Floor 6.8 29.5 334 6.8 21.1 210 3.7 10 170 12.5 29 132

8th Floor 7.2 35.9 399 8 24.3 204 3.9 11.3 190 12.7 32.8 158

7th Floor 8.3 43.6 425 9 28.7 219 4.4 13.4 205 13.4 37.7 181

6th Floor 9.4 50.1 433 9.8 32.2 229 4.5 14.5 222 14.2 42 196

5th Floor 10.5 56.8 441 10.3 34.5 235 4.8 15.3 219 14.7 44.5 203

4th Floor 11.3 61.1 441 10.9 36.5 235 4.8 15.3 219 15.3 46.1 201

3rd Floor 11.5 60.2 423 11.4 37.8 232 4.8 15.3 219 15.8 47 197

2nd Floor 11.3 53 369 11 36.3 230 7.2 26.9 274 11.9 50.5 324

1st Floor 6.7 37.6 461 5 23.5 370 5.2 24.1 363 7.2 37 414

G Floor 0.2 1.3 550 0.1 0.2 100 0 0.1 0.1 1.3 1200

Table 4.9. Comparison of Critical Force for Beams (One Panel) – Bending Moment at Support (kips-ft)





Roof 86.6 86.2 0 28.1 42.6 52 23.9 33.0 38 32.4 47.2 46

11th Floor 94 129.2 37 52.6 112.1 113 49.6 85.2 72 69.7 117.9 69

10th Floor 99.8 184.5 85 45.9 120.5 163 51.8 114.0 120 76.6 156.8 105

9th Floor 99.5 208.7 110 48.1 146.2 204 54.6 142.1 160 75.7 183.9 143

8th Floor 98.2 229.2 133 51.7 172.6 234 55.1 163.0 196 78.3 208.3 166

7th Floor 99.7 255.1 156 54.2 194.1 258 52.9 181.1 242 81 228.1 182

6th Floor 102.9 274.0 166 56.5 212 275 50.1 203.6 306 85.1 248.4 192

5th Floor 104.9 285.9 173 59.2 225.3 281 46.5 222.4 378 88.4 264.0 199

4th Floor 107.1 293.7 174 61 230.3 278 44.3 236.2 433 89.8 273.0 204

3rd Floor 108 295.8 174 61.8 229.8 272 41.7 233.7 460 91.5 278.6 204

2nd Floor 102.9 280.8 173 62 225 263 39.7 196.2 394 99.2 272.8 175

1st Floor 86.6 244.1 182 54.9 197.6 260 36.8 171.2 365 90.1 244.8 172

G Floor 27 127.1 371 22.3 115.8 419 22.6 101.7 350 27.6 130.9 374

Table 4.10. Comparison of Critical Force for Beams (One Panel) – Bending Moment at Midspan (kips-ft)

Interior Beam, B11 Interior Beam, B228 Interior Beam, B224 Edge Beam, B10 Storey

Without EQ With EQ Diff: (%) Without EQ With EQ Diff: (%) Without


Roof 50.8 50.3 -1 21.9 21.9 0 19.9 20.1 1 22.8 22.8 0

11th Floor 78.4 78.1 0 38.3 38.3 0 32.5 32.5 0 67.4 67.4 0

10th Floor 77.5 77.5 0 35.1 35.1 0 28.6 28.6 0 65.2 65.2 0

9th Floor 75.9 75.9 0 34.9 34.9 0 28 29.7 6 63.5 63.5 0

8th Floor 74.6 74.6 0 34.6 34.6 0 27.3 28.9 6 61.2 61.2 0

7th Floor 73.4 73.4 0 34.4 34.4 0 26.7 26.7 0 59.8 59.8 0

6th Floor 72.7 72.7 0 34.2 34.2 0 25.9 26.1 1 58 58.0 0

5th Floor 72.3 72.3 0 34.2 34.2 0 25.7 25.7 0 57.5 57.5 0

4th Floor 71.9 71.9 0 34.2 34.2 0 25.5 25.5 0 57.1 57.1 0

3rd Floor 71.6 71.6 0 34.2 34.2 0 25.2 25.9 3 56 56.0 0

2nd Floor 71.4 71.4 0 33.5 33.5 0 25.3 25.3 0 69.4 69.4 0

1st Floor 60 60.0 0 31.3 31.3 0 31.3 31.3 0 62.8 62.8 0

G Floor 6.1 16.9 177 4.7 17.4 270 4.9 15.6 218 6 18.1 202

CHAPTER 5

DISCUSSIONS, CONCLUSIONS AND RECOMMENDATIONS

5.1. Discussions and Conclusions

In this study of performance of ordinary moment-resisting frame in seismic

zone 2A, structural analysis and design are carried out by using ETABS software. In

making structural analysis, it is necessary to know at the outset the cross-sectional

dimensions of the members. At first, preliminary member sizes are assumed and then

analysed as ordinary moment-resisting frame with gravity and wind loads. If

necessary, the assumed cross-sections are modified and repeated the analysis until

getting the adequate member sizes.

Finally, the ordinary moment-resisting frame was reanalysed with seismic

loads under UBC zone 2A for both factored and unfactored load conditions. But the

ordinary moment-resisting frame was not redesigned.

Storey drift increments are large for both cases but most of the drifts are

within the allowable limit and only one floor exceeds the allowable limit about 0.21

percent.

For columns, axial force increases largely at the corner columns, but there is

only a little increase in end columns and there is not increase at the interior columns.

For beams, increase percent for torsion is high but the magnitudes are not so

large. Torsional moment increases largely in cantilever beams but shear force is not

increase in those beams. Secondly, shear force increase percent is high at the ground

floor beams. Positive bending moment at midspan for beams is not increase in beams

but that is only increases in ground floor beams.

From the comparative study for Ordinary Moment-Resisting Frame without

and with seismic effects, the most critical force for columns is bending moment. Also

for beams, the most critical force is bending moment in interior beams. Between these

of column and beam, more critical force is found in column at the bottom storeys. It is

found that the force and force increments are large mostly at the middle and bottom

storeys. Thus from this study, it may be stated that damage will be initiated at those

99

storeys.

Although percent increments for critical forces are large, the magnitudes of

forces are negligible for some cases. Moreover, the problem may become the less

serious owing to selection practice of to be constructable design.

Only linear elastic responses and equivalent static linear analysis are

considered in this study. If further study will be conducted by using nonlinear elastic

analysis, it may get more suitable solutions.

5.2. Recommendations

On the basis of this study, the following recommendations are done.

1. Further research should be conducted for better understanding about the

behaviour of the building (ordinary moment-resisting frame) under higher

and lower earthquake intensities.

2. Further study should be conducted by using nonlinear elastic analysis and

P-delta effect using the cracked transformed sections.

3. Further study should be conducted by using pushover analysis to know the

failure sequence.

4. Series of research should be conducted for resulting the complete picture

of the problem.

REFERENCE LIST

Fanella, D.A., Mushi, J.A., and Rabbat, B.G. 1999. Notes on ACI-318-99 Building

Code Requirements for Structural Concrete. 7th ed. U.S.A.: Portland Cement

Association.

Fanella, D.A., and Mushi, J.A. Design of Concrete Buildings for Earthquake and

Wind Forces. U.S.A.: Portland Cement Association.

International Conference of Building Officials. 1997. "Structural Engineering

Provisions." Uniform Building Code UBC (1997). U.S.A.: International

Conference of Building Officials.

Lindeburg, M.R., and Baradar, M. 2001. Seismic Design of Building Structures.

8th ed. U.S.A.: Professional Publications, Inc.

Nilson, A.H. 1997. Design of Concrete Structures. 12th ed. Singapore. McGraw Hill

Co. Inc.

Structures and Codes Institute. No Date. Code Master. December 2006

<http:// www.skgoshassociates.com>

Taranath, B.S. 1998. Structural Analysis and Design of Tall Buildings. McGraw Hill

Book Company-Singapore

http://www.skgoshassociates.com/

APPENDICES

APPENDIX A

STRUCTURAL KEY PLAN, DESIGN SECTIONS AND

RESULTS FROM ETABS

Figure A.1. Three Dimensional View of Case Study Building

102

Figure A.2. First Floor Level Beams and Columns Structure Key Plan

103

Figure A.3. Second Floor Level Beams and Columns Structure Key Plan

104

Figure A.4. Typical Floor (third to tenth floor) Level Beams and Columns Structure

Key Plan

105

Figure A.5. Eleventh Floor Level Beams and Columns Structure Key Plan View

106

Figure A.6. Roof Level One Beams and Columns Structure Key Plan View

107

Figure A.7. Concrete Design Sections of Ground Floor Plan View

108

Figure A.8. Concrete Design Sections of First Floor Plan View

109

. Figure A.9. Concrete Design Sections of Second Floor Plan View

110

Figure A.10. Concrete Design Sections of Third Floor to Eleventh Floor Plan View

111

Figure A.11. Concrete Design Sections of Roof Level One Plan View

112

Figure A.12. Concrete Design Sections of Elevation View-1 and Elevation View-9

113

Figure A.13. Concrete Design Sections of Elevation View-2 and Elevation

View-8

114

Figure A.14. Concrete Design Sections of Elevation View-3

115


116


117


118


119

Figure A.19. Frame Span Loads (WALL) of Elevation View-3 (lb-ft Units)

120

Figure A.20. Frame Span Loads (WALL) of Elevation View-7 (lb-ft Units)

121

Figure A.21. Frame Span Loads (WALL) of Elevation View-I (lb-ft Units)

122

Figure A.22. Frame Span Loads (WALL) of Elevation View-J (lb-ft Units)

123

Figure A.23. Uniform Loads GRAVITY (SUPERDL) of First Floor Plan View

(lb-ft Units)

124

Figure A.24. Uniform Loads GRAVITY (SUPERDL) of Third Floor Plan View

(lb-ft Units)

125

Figure A.25. Uniform Loads GRAVITY (LIVE) of First Floor Plan View

(lb-ft Units)

126

Figure A.26. Uniform Loads GRAVITY (LIVE) of Third Floor Plan View

(lb-ft Units)

127

Figure A.27. Axial Force Diagram (COMB2) of Elevation View-E (kip-ft Units)

128

Figure A.28. Axial Force Diagram (COMB2) of Elevation View-7 (kip-ft Units)

129

Figure A.29. Bending Moment in X Direction Diagram (COMB3) of Elevation

View-E (kip-ft Units)

130



131


View-7 (kip-ft Units)

132



133

Figure A.33. Bending Moment in Y Direction Diagram (COMB9) of Elevation


134



135



136



137

Figure A.37. Shear Force Diagram (COMB2) of First Floor Plan View (kip-ft Units)

138

Figure A.38. Shear Force Diagram (COMB20) of First Floor Plan View

(kip-ft Units)

139

Figure A.39. Shear Force Diagram (COMB2) of Fifth Floor Plan View(kip-ft Units)

140

Figure A.40. Shear Force Diagram (COMB20) of Fifth Floor Plan View

(kip-ft Units)

141

Figure A.41. Torsion Diagram (COMB5) of First Floor Plan View (kip-ft Units)

142

Figure A.42. Torsion Diagram (COMB22) of First Floor Plan View (kip-ft Units)

143

Figure A.43. Torsion Diagram (COMB5) of Fifth Floor Plan View (kip-ft Units)

144

Figure A.44. Torsion Diagram (COMB22) of Fifth Floor Plan View (kip-ft Units)

145

Figure A.45. Bending Moment Diagram (COMB4) of First Floor Plan View

(kip-ft Units)

146

Figure A.46. Bending Moment Diagram (COMB19) of First Floor Plan View

(kip-ft Units)

147

Figure A.47. Bending Moment Diagram (COMB4) of Fifth Floor Plan View

(kip-ft Units)

148

Figure A.48. Bending Moment Diagram (COMB19) of Fifth Floor Plan View

(kip-ft Units)

149

Figure A.49. Plan View of Beam and Column Labels

APPENDIX B

ARCHITECTURAL DRAWINGS

Figure B.1. Front Elevation

151

Figure B.2. Side Elevation

152

Figure B.3. Ground Floor and First Floor Plan

153

Figure B.4. Typical Floor (Third Floor to Tenth Floor) Plan

154

Figure B.5. Eleventh Floor Plan

155

Figure B.6. Roof Level One Plan

a study on performance of existing building using ordinary moment resisting frame in seismic zone2a

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