THE USE OF CONSTRUCTION SEQUENCE ANALYSIS IN THE RETROFITTING OF A MISALIGNED BEAM – A CASE OF THE
CAPITAL TOWERS (ATHENS)
CASHLEY FELTON TRINIDAD CHUA 2003 – 01403
SUBMITTED TO THE FACULTY OF THE
COLLEGE OF ENGINEERING AND AGRO-INDUSTRIAL TECHNOLOGY UNIVERSITY OF THE PHILIPPINES LOS BANOS
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF
BACHELOR OF SCIENCE IN CIVIL ENGINEERING
APRIL 2010
ii
The report attached hereto entitled THE USE OF CONSTRUCTION SEQUENCE ANALYSIS IN THE RETROFITTING OF A MISALIGNED BEAM – A CASE OF THE CAPITAL TOWERS (ATHENS), prepared and submitted by Cashley Felton T. Chua in partial fulfillment of the requirements for the degree of Bachelor of Science in Civil Engineering is hereby accepted.
___________________________ ___________________________
ENGR. JENNYL R. ESTIL ENGR. SUNSEEHRAY Panel Member ALESSANDRA B. TIRAZONA
Panel Member
_______________________ _______________________
Date Signed Date Signed
__________________________
PROF. MARLOE B. SUNDO Adviser
______________________
Date Signed
__________________________
PROF. MARLOE B. SUNDO Chairman, CE Department
______________________
Date Signed
_________________________________
DR. ARSENIO N. RESURRECCION Dean
College of Engineering and Agro-Industrial Technology University of the Philippines Los Baños
______________________
Date Signed
vi TABLE OF CONTENTS
Title Page i
Acceptance Sheet ii
About the Author iii
Acknowledgements iv
Table of Contents vi
List of Tables and Figures viii
1. INTRODUCTION
1.1 Project Background 1
1.2 Background of the Study 2
1.3 Significance of the Study 3
1.4 Objectives of the Study 3
1.5 Scope and Limitations 4
1.6 Date and Place of Study 4
2. REVIEW OF RELATED LITERATURE
2.1 Concrete Construction 6
2.1.1 Formwork Installation 6
2.1.2 Concrete Vibration 6
2.1.3 Concrete Curing 8
2.2 Rehabilitation Approaches 8
2.2.1 Global Modification 8
2.2.2 Local Modification 9
2.3 Seismic Retrofitting Strategies 10
2.3.1 Conventional Retrofitting Methods 10
2.3.2 Innovative Retrofitting Methods 11
2.3.2.1 Stiffness Reduction 12
2.3.2.2 Ductility Increase 12
2.3.2.3 Damage Control 12
2.3.2.4 Composite Materials 13
2.3.2.5 Active and Passive Control 13
2.4 Structural Elements 15
2.4.1 Reinforced Concrete Beam 15
2.4.2 Flat Slab 16
2.4.3 Columns 18
2.4.3.1 Slenderness Ratio 19
2.4.3.2 Lateral Buckling 20
2.4.3.3 Reinforcing Bars 20
2.5 Shoring 21
2.5.1 Shoring Types 22
2.5.2 Placing of Shoring 22
2.5.3 Removal of Shoring 23
3. STUDY METHODOLOGY 24
4. OBSERVATIONS
4.1 Beam Misalignment 25
4.2 Installation of Scaffoldings 26
vii 4.3 Installation of I-Beams as Lateral Bracings 27
4.4 Demolition of Existing Beam 32
4.5 Rebar Works 35
4.6 Concrete Works 36
5. DISCUSSION AND ANALYSIS
5.1 Origin of Misalignment 38
5.1.1 Column Misalignment 38
5.1.2 Beam Misalignment 39
5.2 Preliminary Correction Methodology 39
5.3 Evaluation of Beam-Deprived System 40
5.3.1 Designation of Loadings 40
5.3.1.1 Loading Coefficient 41
5.3.1.2 Loading Combo 41
5.3.2 Design of Reinforced Concrete Sections 42 5.3.3 Tower Membrane Without Reinforced Concrete Beam 42
5.4 Analysis of System with New RC Beam 44
5.5 Summary of Analysis 45
5.6 Selection of Retrofitting Methodology 46
5.7 Retrofitting Approaches 47
5.7.1 Conventional Retrofitting Approaches 47
5.7.2 Innovative Retrofitting Methods 48
5.8 Final Correction Methodology 49
5.9 Factors Considered in Concrete Construction 49
5.9.1 Offsetting 49
5.9.2 Formworks 50
5.9.3 Quantity 50
5.9.4 Transport 50
5.9.5 Vibration 50
5.9.6 Finishing 51
5.9.7 Curing 51
6. CONCLUSION 52
7. RECOMMENDATIONS 53
REFERENCES 54
APPENDICES
Appendix A. Floor Plan (8th to 36th) 56
Appendix B. Rebar Cutting List of Beams and Girders (9th to 15th Floor) 57
Appendix C. Off-Setting (Tower 1) 58
Appendix D. Approved Plan (Installation of Additional Rebars) 59 Appendix E. Approved Plan (Installation of I-Beams as Lateral Bracings) 60 Appendix F. Design Strength for Structural Members (Tower 1) 61 Appendix G. Concrete Testing Results (June 8, 2009) 62 Appendix H. Column Schedule (9th Floor Level to 15th Floor Underside) 63
Appendix I. Sample Computations 64
Appendix J. Sample Computations 65
viii LIST OF TABLES and FIGURES
Table/ Figure No. Title Page
Figure 1-1 The Capital Towers 2
Figure 1-2 The Capital Towers Location Map 5
Figure 2-1 Global Modification of the Structural System 9 Figure 2-2 Local Modification of the Structural System 9 Figure 2-3 Conventional Strengthening Methods Used for Seismic
Retrofitting 11
Figure 2-4 Applications of Conventional Strengthening Methods 11
Figure 2-5 Damage Controlled Structure 13
Figure 2-6 Energy Dissipation Devices 15
Figure 2-7 Section Through a Flat Slab 17
Figure 2-8 Section Through a Flat Slab with Drops 17 Figure 2-9 Section Through a Flat Slab with Enlarged Column Heads 17
Figure 2-10 Column with Lateral Ties 19
Figure 2-11 Column with Spirals 19
Figure 2-12 Patented Shores 22
Figure 4-1 Correction with Existing Structure Present 25 Figure 4-2 Shoring Installed (Unit I – 8th Floor) 26 Figure 4-3 Shoring Installed (Unit J – 8th Floor) 26 Figure 4-4 Drilled Holes for Steel Plate Installation (On Beams) 27 Figure 4-5 Manual Drilling of Holes for Steel Plate Installation 27 Figure 4-6 Drilled Holes for Steel Plate Installation (on Columns) 28
Figure 4-7 Torching of Steel Plates 28
Figure 4-8 Acetylene Tanks 29
Figure 4-9 I-Beams Staged On Site 29
Figure 4-10 I-Beams Used as Lateral Bracings 30
Figure 4-11 Welding of I-Beams onto Steel Plates 30
Figure 4-12 Welded I-Beam on Unit I (9th Floor) 31 Figure 4-13 Welded I-Beam on Unit J (9th Floor) 31
Figure 4-14 Manual Demolition of Slab Edges 32
Figure 4-15 Slab Edges Chipped Off (Unit I) 32
Figure 4-16 Misaligned Beam Surface Chipped Off (w/o Bracing) 33 Figure 4-17 Demolition of Misaligned Beam w/ Lateral Bracing 34 Figure 4-18 Demolition of Misaligned Beam (Units I & J) 34
Figure 4-19 Demolished RC Beam (Unit I) 35
Figure 4-20 Demolished RC Beam (Unit J) 35
Figure 5-1 Column Misalignment 38
Figure 5-2 Beam Misalignment 39
Figure 5-3 Load Definition 41
Figure 5-4 Loading Coefficient Modification 41
Figure 5-5 Loading Combination Selection 42
Figure 5-6 3-D View of TCT-Athens Membrane with Elevation View 43 Figure 5-7 Elevation View of Columns C2 and C3 (without beam) Showing
the Required Design Reinforcement Area 44
ix Figure 5-8 3-D View of TCT-Athens Membrane with pinned Beam
Replacement 44
Figure 5-9 Elevation View of Columns C2 and C3 (with beam) Showing
the Required Design Reinforcement Area 45
Figure 5-10 Original Rebar Cutting List (Beam G-4) 46 Figure 5-11 Cutting List with Additional Rebars (Beam G-4) 46
Figure 5-12 Post-Cast Shear Wall 48
Figure 5-13 External Steel Bracing 48
Table 4.1 Values for Strength of Concrete for Percent Age of 28 Days
Strength 37
