influence of the lrfd bridge design specifications on seismic design in alabama

583 Pages·2011·4.89 MB·English

Research Report IR-11-01

INFLUENCE OF THE LRFD BRIDGE DESIGN
SPECIFICATIONS ON SEISMIC DESIGN IN ALABAMA

Submitted to

Highway Research Center

Prepared by

Paul J. Coulston
Justin D. Marshall

AUGUST 2011
1. Report No. 2. Government Accession No. 3. Recipient Catalog No.
IR-11-01

4 Title and Subtitle 5 Report Date
INFLUENCE OF THE LRFD BRIDGE DESIGN August 2011
SPECIFICATIONS ON SEISMIC DESIGN IN ALABAMA
6 Performing Organization
Code

7. Author(s) 8 Performing
Paul J. Coulston
Organization Report No.
Justin D. Marshall

9 Performing Organization Name and Address 10 Work Unit No. (TRAIS)
Highway Research Center
Department of Civil Engineering
11 Contract or Grant No.
238 Harbert Engineering Center

Auburn, AL 36849
12 Sponsoring Agency Name and Address 13 Type of Report and Period
Covered

14 Sponsoring Agency Code

15 Supplementary Notes

16 Abstract
The Alabama Department of Transportation (ALDOT) is in the process of transitioning from the AASHTO
Standard Specification for Highway Bridges to the LRFD Bridge Design Specifications. One significant
difference between the two specifications is the seismic design provisions. From a practical point of view, the
desire is that typical details can be developed for the worst-case scenarios which can be implemented for
bridges throughout the state without a significant cost premium. To determine the effects of the updated seismic
provisions on current practice, an initial study of existing bridges was completed. Three typical, multi-span,
prestressed concrete I-girder bridges were selected for the study. The primary bridge geometry variables were
span length, pier height and pier configuration. The bridges’ Earthquake Resisting Systems were re-designed
for the worst conditions in the state. This paper discusses the changes made. There was a modification to the
connection between the substructure and substructure. The amount of hoop reinforcing in the columns, drilled
shafts and struts was increased. Typical, economical details were not viable for all seismic hazards in Alabama.
17 Key Words 18 Distribution Statement
Seismic Design, Displacement-based Design, No restrictions. This document is
Bridge Design available to the public through the
National Technical Information Service,
Springfield, Virginia 22161
19 Security 20 Security 21 No. of pages 22 Price
Classification (of Classification (of 571
this report) this page)
Unclassified Unclassified
_______________________
Research Report No. IR-11-01

INFLUENCE OF THE LRFD BRIDGE DESIGN
SPECIFICATIONS ON SEISMIC DESIGN IN ALABAMA

Submitted to

Highway Research Center

Prepared by

Paul J. Coulston
Justin D. Marshall

AUGUST 2011
DISCLAIMERS

The contents of this report reflect the views of the authors, who are responsible for the facts and
the accuracy of the data presented herein. The contents do not necessarily reflect the official
views or policies of Auburn University or the Federal Highway Administration. This report does
not constitute a standard, specification, or regulation.

NOT INTENDED FOR CONSTRUCTION, BIDDING, OR PERMIT PURPOSES

Justin D. Marshall, Ph.D., P.E.
Research Supervisors

i
ABSTRACT

The Alabama Department of Transportation (ALDOT) is in the process of transitioning from the
AASHTO Standard Specification for Highway Bridges to the LRFD Bridge Design Specifications.
One significant difference between the two specifications is the seismic design provisions. From a
practical point of view, the desire is that typical, economical details can be developed for the
worst-case scenarios, which can be implemented for bridges throughout the state without a
significant cost premium. To determine the effects of the updated seismic provisions on current
practice, a study of existing bridges was completed. Three typical, multi-span, prestressed
concrete I-girder bridges were selected for the study. In order to bracket the demands for typical
bridges, the primary bridge geometry variables were span length, pier height and pier
configuration. The bridges’ Earthquake Resisting Systems were re-designed for the worst
conditions for the state of Alabama. This paper discusses the changes made to the three bridges
in order to meet the requirements.
After the re-design of the three bridges, a few conclusions were drawn. A stronger
connection is required between the substructure and substructure. The amount of hoop
reinforcing in the columns, drilled shafts and struts was increased. Typical details for the worst
seismic scenario in Alabama were not economical for all areas of the state.

ii
TABLE OF CONTENTS

LIST OF TABLES ................................................................................................................................. vi
LIST OF FIGURES ............................................................................................................................... vii
LIST OF SYMBOLS ............................................................................................................................... ix

CHAPTER 1: INTRODUCTION .............................................................................................................. 1
1.1 Problem Statement ................................................................................................................... 1
1.2 Objective and Scope ................................................................................................................. 1
1.3 Document Organization ............................................................................................................ 2

CHAPTER 2: LITERATURE REVIEW .................................................................................................. 3
2.1 Introduction .............................................................................................................................. 3
2.2 History ....................................................................................................................................... 3
2.3 Comparison of the Seismic Design Specifications... ................................................................ 4
2.4 Previous Research .................................................................................................................... 7
2.5 Conclusion ................................................................................................................................ 8

CHAPTER 3: SEISMIC BRIDGE DESIGN ............................................................................................. 9
3.1 Introduction ............................................................................................................................... 9
3.2 Design Process ....................................................................................................................... 10
3.3 Design Process for the Guide Specification ........................................................................... 10
3.3.1 Initial Steps for the Design ............................................................................................ 10
3.3.2 Applicability of Specification .......................................................................................... 11
3.3.3 Performance Criteria ..................................................................................................... 11
3.3.4 Foundation Investigation and Liquefaction .................................................................... 11
3.3.5 Earthquake Resisting System ....................................................................................... 11
3.3.6 General Design Response Spectrum ............................................................................ 12
3.3.7 Displacement Demand Analysis.................................................................................... 12
3.3.8 Column Design .............................................................................................................. 14
3.3.9 Seismic Design Category B Detailing ........................................................................... 17
3.3.10 Requirements outside the Plastic Hinge Region ......................................................... 19
3.4 Design Process for the LRFD Specification............................................................................ 19
3.4.1 Major Differences from the Guide Specification ............................................................ 19
3.4.2 Initial Steps for Design .................................................................................................. 20
3.4.3 Column Design .............................................................................................................. 21
3.4.4 Requirements outside the Plastic Hinge Zone .............................................................. 23

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3.5 Connection Design .................................................................................................................. 23
3.5.1 Connection between Substructure and Superstructure ................................................ 23
3.5.2 Connection of Drilled Shaft ............................................................................................ 26
3.6 Conclusion .............................................................................................................................. 27

CHAPTER 4: BRIDGE DESIGN ........................................................................................................... 28
4.1 Introduction ............................................................................................................................. 28
4.2 Oseligee Creek Bridge ............................................................................................................ 28
4.2.1 Description of the Bridge ............................................................................................... 28
4.2.2 Results from Guide Specification Design ...................................................................... 29
4.2.3 Results from LRFD Specification Design ...................................................................... 33
4.2.4 Comparison of Standard, Guide, and LRFD Specifications .......................................... 35
4.3 Little Bear Creek Bridge .......................................................................................................... 40
4.3.1 Description of the Bridge ............................................................................................... 40
4.3.2 Results from Guide Specification Design ...................................................................... 41
4.3.3 Results from LRFD Specification Design ...................................................................... 46
4.3.4 Comparison of Standard, Guide, and LRFD Specifications .......................................... 48
4.4 Scarham Creek Bridge ............................................................................................................ 54
4.4.1 Description of the Bridge ............................................................................................... 54
4.4.2 Results from Guide Specification .................................................................................. 55
4.4.3 Results from LRFD Specification .................................................................................. 60
4.4.4 Comparison of Standard, Guide, and LRFD Specifications .......................................... 63
4.5 Conclusion .............................................................................................................................. 74

CHAPTER 5: CONCLUSIONS ............................................................................................................. 76
5.1 Summary of Conclusion ......................................................................................................... 76
5.2 Future Needs and Recommended Future Work ..................................................................... 77

REFERNECES ..................................................................................................................................... 78

APPENDIX A: OSELIGEE CREEK BRIDGE GUIDE SPECIFICATION DESIGN ............................. 79

APPENDIX B: OSELIGEE CREEK BRIDGE LRFD SPECIFICATION DESIGN .............................. 135

APPENDIX C: INTERACTION DIAGRAMS FOR OSELIGEE CREEK BRIDGE .............................. 192

APPENDIX D: LITTLE BEAR CREEK BRIDGE GUIDE SPECIFICATION GUIDE .......................... 204

APPENDIX E: LITTLE BEAR CREEK BRIDGE LRFD SPECIFICATION DESIGN ......................... 263
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APPENDIX F: INTERACTION DIAGRAMS FOR LITTLE BEAR CREEK BRIDGE ......................... 322

APPENDIX G: SCARHAM CREEK BRIDGE GUIDE SPECIFICATION DESIGN ............................ 342

APPENDIX H: SCARHAM CREEK BRIDGE LRFD SPECIFICATION DESIGN .............................. 447

APPENDIX I: INTERACTION DIAGRAMS FOR SCARHAM CREEK BRIDGE ............................... 547

v
LIST OF TABLES

Table 2.1. Oseligee Creek Bridge Bent 3 Changes .......................................................................... 5
Table 3.1. Response Modification Factors for LRFD Specifications ............................................... 20
Table 4.1. Pushover Analysis Results ............................................................................................ 30
Table 4.2. Oseligee Creek Bridge Bent 2 Design Changes ............................................................ 35
Table 4.3. Oseligee Creek Bridge Bent 2 Design Changes ............................................................ 35
Table 4.4. Oseligee Creek Bridge Connection Design Changes .................................................... 40
Table 4.5. Pushover Analysis Results ............................................................................................. 42
Table 4.6. Little Bear Creek Bridge Column Design Changes for Bent 2 ....................................... 48
Table 4.7. Little Bear Creek Bridge Column Design Changes for Bent 3 ....................................... 48
Table 4.8. Little Bear Creek Bridge Drilled Shaft Design Changes for Bent 2 ................................ 49
Table 4.9. Little Bear Creek Bridge Drilled Shaft Design Changes for Bent 3 ................................ 49
Table 4.10. Little Bear Creek Bridge Connection Design Changes .................................................. 54
Table 4.11. Pushover Analysis Results for Scarham Creek ............................................................. 56
Table 4.12. Scarham Creek Bridge Bent 2 Design Changes ............................................................ 63
Table 4.13. Scarham Creek Bridge Bent 3 Design Changes ............................................................ 63
Table 4.14. Scarham Creek Bridge Bent 4 Design Changes ............................................................ 64
Table 4.15. Scarham Bridge Strut 2 and 4 Design Changes ............................................................ 64
Table 4.16. Scarham Bridge Strut 3 Design Changes ...................................................................... 64
Table 4.17. Scarham Creek Bridge Connection Changes ................................................................ 74

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LIST OF FIGURES

Figure 2.1. Comparison of the response spectrum for the Standard Specification and
Guide Specification located at the Northeast corner of Alabama .................................... 6
Figure 3.1. Load Path Diagram ........................................................................................................ 10
Figure 3.2 Loading Directions .......................................................................................................... 14
Figure 3.3 Seismic Hoop Detail ....................................................................................................... 18
Figure 3.4 Illinois DOT Seismic Hoop Detail (Tobias et. al. 2008) .................................................. 18
Figure 3.5 Standard Specification Connection used by ALDOT (Taken from ALDOT
Standard Details Standard Drawing I-131 Sheet 7 of 8) ................................................ 24
Figure 3.6 Modified Substructure to Superstructure Connection .................................................... 24
Figure 4.1. 3-D SAP Model of Oseligee Creek Bridge ..................................................................... 28
Figure 4.2. Response Spectrum of Oseligee Creek Bridge ............................................................. 29
Figure 4.3. Oseligee Creek Bridge Pushover Curve for Load Case Bent 2 Transverse
Direction ......................................................................................................................... 30
Figure 4.4. Oseligee Creek Bridge Abutment Connection (Expansion) ........................................... 32
Figure 4.5. Oseligee Creek Bridge Bent 2 & 3 Connections ............................................................ 32
Figure 4.6. Oseligee Creek Bridge Abutment Connection (Expansion) ........................................... 34
Figure 4.7. Oseligee Creek Bridge Bent 2 & 3 Connections ............................................................ 34
Figure 4.8. Oseligee Creek Bridge Bent 2 Guide Specification vs. Standard Specification............. 36
Figure 4.9. Oseligee Creek Bridge Bent 3 Guide Specification vs. Standard Specification............. 37
Figure 4.10. Oseligee Creek Bridge Bent 2 LRFD Specification vs. Standard Specification ............. 38
Figure 4.11. Oseligee Creek Bridge Bent 3 LRFD Specification vs. Standard Specification ............. 39
Figure 4.12. 3-D SAP Model of Little Bear Creek Bridge ................................................................... 41
Figure 4.13. Response Spectrum for Little Bear Creek Bridge .......................................................... 42
Figure 4.14. Little Bear Creek Bridge Pushover Curve for Load Case Bent 3 Transverse
Direction ......................................................................................................................... 43
Figure 4.15. Little Bear Creek Abutment Connection (Expansion) .................................................... 44
Figure 4.16. Little Bear Creek Bent 2 & 3 Connections for Bulb Tee Girders .................................... 45
Figure 4.17. Little Bear Creek Bent 2 & 3 Connections for Type III Girders ...................................... 45
Figure 4.18. Little Bear Creek Abutment Connection for Type III Girders.......................................... 46
Figure 4.19. Little Bear Creek Bent 2 & 3 Connections for Bulb Tee Girders .................................... 47
Figure 4.20. Little Bear Creek Bent 2 & 3 Connections for Type III Girders ...................................... 47
Figure 4.21. Little Bear Creek Bridge Bent 2 Guide Specification vs. Standard
Specification ................................................................................................................... 50
Figure 4.22. Little Bear Creek Bridge Bent 3 Guide Specification vs. Standard
Specification ................................................................................................................... 51
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