Post on 07-Aug-2018
transcript
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 1/103
Western Bridge Engineers’ Seminar September 24-26, 2007 1
AASHTOLRFD Guide Specifications
for Seismic Design of Highway Bridges
Roy A. Imbsen
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 2/103
Western Bridge Engineers’ Seminar September 24-26, 2007 2
Presentation Topics
♦Background-AASHTO LRFD Guide Specifications
♦Excerpts selected from the Guide Specifications
♦AASHTO T-3 Committee recent activities
supporting adoption as a Guide Specification
♦Current status
♦Planned activities post-adoption
♦Conclusions
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 3/103
Western Bridge Engineers’ Seminar September 24-26, 2007 3
AASHTO T-3 Working Group that defined
the objectives and directed the project
♦ Rick Land, CA (Past chair)
♦ Harry Capers, NJ (Past Co-chair)
♦ Richard Pratt, AK (Current chair)
♦Kevin Thompson, CA (Current Co-chair)
♦ Ralph Anderson, IL
♦ Jugesh Kapur, WA
♦ Ed Wasserman, TN♦ Paul Liles, GA
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 4/103
Western Bridge Engineers’ Seminar September 24-26, 2007 4
Project Phases♦ 2002 AASHTO T-3 Committee Meeting
♦ 2003 MCEER/FHWA – Task F3-4 Road Map
– Task F3-5 Suggested Approach
♦ 2004 NCHRP 20-07/Task 193 AASHTO Guide Specifications
for LRFD Seismic Bridge Design♦ AASHTO T-3 Committee and Volunteer States
– 2006 Trial Designs
– 2007 Technical Review
♦ 2007 AASHTO Adoption as a Guide Specification with thecontinuous support and guidance of the T-3 Committee
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 5/103
Western Bridge Engineers’ Seminar September 24-26, 2007 5
Overall T-3 Project Objectives
♦Assist T-3 Committee in developing a LRFD
Seismic Design Specification using availablespecifications and current research findings
♦Develop a specification that is user friendly and
implemental into production design
♦Complete six tasks specifically defined by theAASHTO T-3 Committee, which were based onthe NCHRP 12-49 review comments
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 6/103
Western Bridge Engineers’ Seminar September 24-26, 2007 6
Stakeholders Table
George Lee, MCEER, Chair
Rick Land, T-3 Chair
Geoff Martin, MCEER
Joe Penzien, HSRC, EQ V-team
John Kulicki, HSRC
Les Youd, BYU
Joe Wang, Parsons, EQ V-team
Lucero Mesa, SCDOT V-team
Rick Land, CA (Past chair)
Harry Capers, NJ
(Past Co-chair)
Richard Pratt, AK
(Current chair)
Kevin Thompson, CA
(Current Co-chair)
Ralph Anderson, IL
Jugesh Kapur, WA
Ed Wasserman, TN
Paul Liles, GA
Roy Imbsen, IAI
Roger Borcherdt, USGS
Po Lam, EMI
E. V. Leyendecker, USGS
Lee Marsh, Berger/Abam
Randy Cannon, formerly
SCDOT
Technical Review Panel
(to be invited)
T-3 Working GroupIAI Team
(as needed)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 7/103
Western Bridge Engineers’ Seminar September 24-26, 2007 7
THE MEMBERS OF THE
TECHNICAL REVIEW TEAM♦ MARK MAHAN, CA DOT (TEAM LEADER)
♦ ROY A. IMBSEN, IMBSEN CONSULTING♦ ELMER MARX, AK DOT & PF
♦ JAY QUIOGUE, CA DOT
♦ CHRIS UNANWA, CA DOT
♦ FADEL ALAMEDDINE, CA DOT♦ CHYUAN-SHEN LEE, WA STATE DOT
♦ STEPHANIE BRANDENBERGER, MT DOT
♦ DANIEL TOBIAS, IL DOT
♦ DERRELL MANCEAUX, FHWA
♦ LEE MARSH, BERGER/ABAM
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 8/103
Western Bridge Engineers’ Seminar September 24-26, 2007 8
THE STATES WHO PERFORMED
THE TRIAL DESIGNS♦ ALASKA
♦ ARKANSAS♦ CALIFORNIA
♦ ILLINOIS
♦ INDIANA
♦ MISSOURI♦ MONTANA
♦ NEVADA
♦ OREGON
♦ TENNESSEE
♦ WASHINGTON STATE
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 9/103
Western Bridge Engineers’ Seminar September 24-26, 2007 9
Support
♦MCEER/FHWA “Seismic Vulnerability of the
Highway System” Task F3-4 AASHTO T-3
Support
♦ NCHRP 20-07/Task 193 Updating“Recommended LRFD Guidelines for Seismic
Design of Highway Bridges”
♦AASHTO T-3 Committee
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 10/103
Western Bridge Engineers’ Seminar September 24-26, 2007 10
Background-NCHRP 20-07
Task 6 Report (1.1)
♦ Review Reference Documents
♦ Finalize Seismic Hazard Level♦ Expand the Extent of the No-Analysis Zone
♦ Select the Most Appropriate Design Procedure for
Steel Bridges♦ Recommend Liquefaction Design Procedure
♦ Letter Reports for Tasks 1-5 (Ref. NCHRP 20-07/Task193 Task 6 Report for Updating “Recommended
LRFD Guidelines for Seismic Design of HighwayBridges” Imbsen & Associates, Inc., of TRC )
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 11/103
Western Bridge Engineers’ Seminar September 24-26, 2007 11
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 12/103
Western Bridge Engineers’ Seminar September 24-26, 2007 12
Table of Contents♦ 1. Introduction
♦ 2. Symbols and Definitions♦ 3. General Requirements
♦ 4. Analysis and Design Requirements
♦ 5. Analytical Models and Procedures♦ 6. Foundation and Abutment Design Requirements
♦ 7. Structural Steel Components
♦8. Reinforced Concrete Components♦ Appendix A – Rocking Foundation Rocking Analysis
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 13/103
Western Bridge Engineers’ Seminar September 24-26, 2007 13
Table of Contents♦ 1. Introduction
• 1.1 Background (NCHRP 20-07/Task 193 Task 6 Report)♦ 2. Symbols and Definitions
♦ 3. General Requirements
♦ 4. Analysis and Design Requirements
♦ 5. Analytical Models and Procedures
♦ 6. Foundation and Abutment Design Requirements
♦ 7. Structural Steel Components
♦ 8. Reinforced Concrete Components♦ Appendix A Foundation Rocking Analysis
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 14/103
Western Bridge Engineers’ Seminar September 24-26, 2007 14
Background Task 2 - Seismic
Hazard Level (1.1)
♦ Design against the Effects Ground Shaking Hazard ♦ Selection of a Return Period for Design less than 2500 Years
♦ Inclusion of the USGS 2002 Update of the National SeismicHazard Maps
♦ Effects of Near Field and Fault Rupture to be addressed in afollowing Task
♦ Displacement Based Approach with both Design SpectralAcceleration and corresponding Displacement Spectra provided
♦ Hazard Map under the control of AASHTO with each Statehaving the option to Modify or Update their own State Hazardusing the most recent Seismological Studies
Recommended approach to addressing the seismic hazard:
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 15/103
Western Bridge Engineers’ Seminar September 24-26, 2007 15
Background Task 2-Seismic Hazard
(1.1)
♦ NEHRP 1997 Seismic Hazard Practice
♦ Caltrans Seismic Hazard Practice
♦ NYCDOT and NYSDOT Seismic Hazard Practice
♦ NCHRP 12-49 Seismic Hazard Practice
♦ SCDOT Seismic Hazard Practice
♦ Site-Specific Hazard Analyses Conducted for CriticalBridges
Seismic Hazard Practice can be best illustrated in looking
at the following sources:
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 16/103
Western Bridge Engineers’ Seminar September 24-26, 2007 16
Background Seismic Hazard for
Normal Bridges (1.1)♦ Selection of a lower return period for Design is made
such that Collapse Prevention is not compromisedwhen considering large historical earthquakes.
♦ A reduction can be achieved by taking advantage of
sources of conservatism not explicitly taken intoaccount in current design procedures.
♦ The sources of conservatism are becoming moreobvious based on recent findings from bothobservations of earthquake damage and experimentaldata.
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 17/103
Western Bridge Engineers’ Seminar September 24-26, 2007 17
Background Task 2-Sources of
Conservatism (1.1)
Sou rce of Cons ervatism Safety Factor
Compu ta tional vs. Experiment a l Displacement
Capa city of Component s
1.3
Effect ive Damping 1.2 to 1.5
Dyna mic Effect (i.e., st ra in ra te effect ) 1.2
Push over Techniques Govern ed by First Plast ic
Hinge to Reach Ultima te Capa city
1.2 to 1.5
Out of Phase Displacement a t Hinge Seat Addressed in Task 3
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 18/103
Western Bridge Engineers’ Seminar September 24-26, 2007 18
Idealized Load – Deflection Curve
Considered
in Design
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 19/103
Western Bridge Engineers’ Seminar September 24-26, 2007 19
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 20/103
Western Bridge Engineers’ Seminar September 24-26, 2007 20
Design Approaches
-Force- -Displacement-
♦ Division 1A and Current
LRFD Specification♦ Complete w/ service load
requirements
♦ Elastic demand forces w/
applied prescribed ductility
“R”
♦ Ductile response is assumed
to be adequate w/overification
♦ New 2007 Guide Specification
♦ Complete w/ service loadrequirements
♦ Displacements demands w/
displacement capacity checks
for deformability
♦ Ductile response is assured
with limitations prescribed for
each SDC
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 21/103
Western Bridge Engineers’ Seminar September 24-26, 2007 21
Background Seismic Hazard
Normal Bridges (1.1)
♦ An appropriate method to design adequate seatwidth(s) considering out of phase motion.
♦ An appropriate method to design the ductilesubstructure components without undue conservatism
Two distinctly different aspects of the design process
need to be provided:
These two aspects are embedded with different levels ofconservatism that need to be calibrated against the single
level of hazard considered in the design process.
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 22/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 22
Background Task 3
Expand the No-Analysis Zone (1.1)
P − Δ
♦ At a minimum, maintain the number of bridges under the
“Seismic Demand Analysis” by comparing ProposedGuidelines to AASHTO Division I-A.
♦ Develop implicit procedures that can be used reduce the
number of bridges where “Seismic Capacity Analysis” needs to
be performed, This objective is accomplished by identifying athreshold where an implicit procedures can be used (Drift
Criteria, Column Shear Criteria).
♦ Identify threshold where “Capacity Design” shall be used. Thisobjective is achieved in conjunction with the “Seismic Capacity
Analysis” requirements.
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 23/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 23
Guidelines-General
Seismic Load Path and Affected Components
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 24/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 24
Guidelines
Performance Criteria
♦ Type 1 – Design a ductile substructure with an
essentially elastic superstructure.♦ Type 2 – Design an essentially elastic
substructure with a ductile superstructure.
♦ Type 3 – Design an elastic superstructure andsubstructure with a fusing mechanism at theinterface between the superstructure and the
substructure.
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 25/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 25
Guidelines
Performance Criteria
♦ For Type 3 choice, the designer shall assess the
overstrength capacity for the fusing interfaceincluding shear keys and bearings, then design for anessentially elastic superstructure and substructure.
♦The minimum overstrength lateral design force shall be calculated using an acceleration of 0.4 g or theelastic seismic force whichever is smaller.
♦ If isolation devices are used, the superstructure shall
be designed as essentially elastic.
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 26/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 26
Table of Contents♦ 1. Introduction
– 1.3 Flow Charts♦ 2. Symbols and Definitions
♦ 3. General Requirements
♦ 4. Analysis and Design Requirements
♦ 5. Analytical Models and Procedures
♦ 6. Foundation and Abutment Design Requirements
♦ 7. Structural Steel Components
♦ 8. Reinforced Concrete Components♦ Appendix A – Rocking Foundation Rocking Analysis
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 27/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 27
LRFD
Flow Chart
Fig 1.3-1A
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 28/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 28
LRFDFlow Chart
Fig 1.3-1B
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 29/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 29
LRFDFlow Chart
(Fig 1.3-5A )
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 30/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 30
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 31/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 31
Table of Contents♦ 1. Introduction
♦ 2. Symbols and Definitions♦ 3. General Requirements
♦ 4. Analysis and Design Requirements
♦5. Analytical Models and Procedures♦ 6. Foundation and Abutment Design Requirements
♦ 7. Structural Steel Components
♦ 8. Reinforced Concrete Components
♦ Appendix A – Rocking Foundation Rocking Analysis
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 32/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 32
Applicability (3.1)
♦Design and Construction of New Bridges
♦Bridges having Superstructures Consisting of:
– Slab
– Beam – Girder
– Box Girder
♦Spans less than 500 feet
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 33/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 33
Performance Criteria (3.2)
♦One design level for life safety
♦Seismic hazard level for 7% probability of
exceedance in 75 years (i.e.,1000 year return
period)
♦Low probability of collapse
♦May have significant damage and disruption to
service
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 34/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 34
Table of Contents♦ 1. Introduction
♦ 2. Symbols and Definitions♦ 3. General Requirements
3.3 Earthquake Resisting Systems
♦ 4. Analysis and Design Requirements
♦ 5. Analytical Models and Procedures
♦ 6. Foundation and Abutment Design Requirements
♦ 7. Structural Steel Components
♦ 8. Reinforced Concrete Components♦ Appendix A – Rocking Foundation Rocking Analysis
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 35/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 35
Earthquake Resisting Systems-ERS
(3.3)
♦ Required for SDC C and D
♦ Must be identifiable within the bridge system
♦ Shall provide a reliable and uninterrupted load path
♦ Shall have energy dissipation and/or restraint to controlseismically induced displacements
♦ Composed of acceptable Earthquake Resisting Elements
(ERE)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 36/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 36
Permissible
Earthquake
Resisting
Systems
(ERS)
ERS (3.3)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 37/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 37
Permissible
EarthquakeResisting
Elements that
Require Owner’s
Approval
ERS (3.3)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 38/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 38
Table of Contents♦ 1. Introduction
♦2. Symbols and Definitions
♦ 3. General Requirements
Seismic Ground Shaking Hazard
♦ 4. Analysis and Design Requirements
♦ 5. Analytical Models and Procedures
♦ 6. Foundation and Abutment Design Requirements
♦ 7. Structural Steel Components
♦ 8. Reinforced Concrete Components♦ Appendix A – Rocking Foundation Rocking Analysis
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 39/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 39
Seismic Hazard (3.4)
♦ 7% Probability of Exceedence in 75 Years
♦ AASHTO-USGS Technical Assistance Agreement to:
– Provide paper maps – Develop ground motion software
♦ Hazard maps for 50 States and Puerto Rico – Conterminous 48 States-USGS 2002 maps
– Hawaii-USGS 1998 maps – Puerto Rico-USGS 2003 maps
– Alaska-USGS 2006 maps
♦ Maps for Spectral Accelerations Site Class B
– Short period (0.2 sec.) – Long period (1.0 sec.)
– Peak (PGA 0.0 sec.)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 40/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 40
Design
Spectrum,Figure 3.4.1-1
Seismic Hazard
2-Point Method
for Design
SpectrumConstruction
(3.4)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 41/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 41
Trial Design MO-2 (3.1)38'-10"
8'-10" 8'-10" 8'-10" 8'-10"
3'-3" DEEP
PS/PC I-GIRDER
TYP
3'-3"x3'-6" BEAM
3'-0" COLUMNS (TYP) 13'-0"
(TYP)
8 12" SLAB
3'-3"
2 6 ' - 6 "
4 ' - 0 "
V A R I E S
ELV -3.0
13 - #8
(TYP)
1'-8"
(TYP)
5'-0"
(TYP)
COLUMN
1'-2" CIP
CONC PILE
W/STEEL
CASING, TYP
9'-14" CIP (TYP)
(13'x13'x4' PILE CAP)
SECTION-INTERMEDIATE PIER1 _
SCALE: 1/16" = 1'-0"
Elevation of Intermediate Pier
14'-4" 14'-4"
ELV 0
COLUMN
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 42/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 42
Trial Design MO-2 (3.1)
B R G
A B U T
A
B E N
T 1
B E N
T 2
B R G
A B U T
B
14" CIP
CONC PILEW/STEEL
CASING, TYP
13'-0"
ELEVATION - MISSOURI SITE1'=40'
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 43/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 43
Figure 3.4.1-2a Peak Horizontal
Ground Acceleration for the
Conterminous United States
(Western) With 7 Percent
Probability of Exceedance in
75 Years (Approx. 1000 Year
Return Period).
AASHTO/
USGS Maps
(3.4.1)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 44/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 44
AASHTO/USGS Maps (3.4.1)
LRFD –
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 45/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 45
LRFD
HorizontalSpectral
Response Acceleration
(3.4.1)AASHTO/USGS Maps
Region 3
0.2 second period
Longitude 89.817o West
Latitude 36.000o NorthAcceleration=1.89g
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 46/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 46
Site Effects Fv (3.4.2)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 47/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 47
Seismic Hazard
2-Point Methodfor Design
Spectrum
Construction
(3.4)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 48/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 48
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 49/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 49
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 50/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 50
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 51/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 51
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 52/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 52
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 53/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 53
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 54/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 54
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 55/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 55
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 56/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 56
Table of Contents♦ 1. Introduction
♦ 2. Symbols and Definitions
♦ 3. General Requirements
3.5 Seismic Design Category
♦ 4. Analysis and Design Requirements
♦ 5. Analytical Models and Procedures♦ 6. Foundation and Abutment Design Requirements
♦ 7. Structural Steel Components
♦ 8. Reinforced Concrete Components♦ Appendix A – Rocking Foundation Rocking Analysis
SDC Range of Applicable
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 57/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 57
SDC Range of Applicable
Analysis (3.5)
♦ Seismic Demand Analysis requirement
♦ Seismic Capacity Analysis requirement♦ Capacity Design requirement
♦ Level of seismic detailing requirement including four
tiers corresponding to SDC A, B, C and D♦ Earthquake Resistant System
Four Seismic Design Categories (SDC)
A, B, C and D encompassing requirements for:
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 58/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 58
SDC (3.5)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 59/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 59
SDC A (3.5)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 60/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 60
SDC B (3.5)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 61/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 61
SDC C (3.5)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 62/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 62
SDC D (3.5)
SDC Core Flowchart (3 5)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 63/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 63
SDC Core Flowchart (3.5)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 64/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 64
Table of Contents♦ 1. Introduction
♦ 2. Symbols and Definitions
♦ 3. General Requirements
♦ 4. Analysis and Design Requirements
♦ 5. Analytical Models and Procedures
♦ 6. Foundation and Abutment Design Requirements
♦ 7. Structural Steel Components
♦ 8. Reinforced Concrete Components
♦ Appendix A – Rocking Foundation Rocking Analysis
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 65/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 65
Balanced
Stiffness
Recommendation(4.1)
Seismic Analysis Using SAP2000
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 66/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 66
Seismic Analysis Using SAP2000
Bridge Modeler
Missouri Design Example
3-Span P/S I-girder bridge
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 67/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 67
Balanced Frame SDC D (4.1.2)
♦ Any Two Bents Within a Frame or Any TwoColumns Within a Bent
Constant Width Frames:
(4.1.2-1)
Variable Width Frames:
(4.1.2-2)
5.0≥e
j
e
i
k
k
5.0≥i
e
j
j
e
i
mk mk
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 68/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 68
Balanced Bent (4.1.2)♦ Adjacent Bents Within a Frame or Adjacent
Columns Within a BentConstant Width Frames:
(4.1.2-3)
Variable Width Frames:
(4.1.2-4)
75.0≥e
j
e
i
k
k
75.0≥i
e j
j
e
i
mk
mk
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 69/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 69
Analysis Procedure (4.2)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 70/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 70
Displacement Demands (4.3)♦Horizontal ground motions for SDC B,C, & D
determined independently along two axes andcombined
♦Displacement modification for other than 5%
damped bridges having energy dissipation atabutments
♦Displacement magnification for short period
short period structures
Combination of Seismic
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 71/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 71
Displacement Demands (4.4)♦LOAD CASE 1:
100% Longitudinal Displacement Demands(absolute value), Combined with 30%Transverse Displacement Demands (absolutevalue)
♦LOAD CASE 2: 100% TransverseDisplacement Demands (absolute value),Combined with 30% Longitudinal DisplacementDemands (absolute value)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 72/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 72
Design for SDC B, C, &D (4.7)♦ Conventional – Full ductility structures with a plastic
mechanism having 4.0<uD6.0 for a bridge in SDC D♦ Limited ductility – For structures with a Plastic
mechanism readily accessible for inspection having
uD<4.0 for a bridge in SDC B or C♦ Limited Ductility – For structures having a plastic
mechanism working in concert with a protective
system. The plastic hinge may or may not form. Thisstrategy is intended for SDC C or D
Displacement Capacity
for SDC B and C (4 8 1)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 73/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 73
for SDC B and C (4.8.1)
Displacement Capacity for SDC D (4.8.2)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 74/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 74
p p y ( )
♦ Inelastic Quasi-Static Pushover analysis (IQPA) is requiredto determine realistic displacement capacities as it reachesit’s limit states
♦ IQPA is an incremental linear analysis which captures theoverall nonlinear behavior of the structure and it’s elements
through each limit state♦ The IQPA model includes the redistribution of forces as
each limit state is reached
♦ Foundation effects may also be included in the model
Member Ductility Requirement for
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 75/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 75
SDC D (4.9)
Member Ductility Requirement for
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 76/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 76
(4.9-5)
Where:
= plastic displacement demand (in.)
= idealized yield displacement corresponding
to the idealized yield curvature, ,
shown in figure 8.5-1 (in.)
Pile shafts should be treated similar to columns.
SDC D (4.9)
yiΔ
pd Δ
yi
pd
D
Δ
Δ+= 1μ
yiφ
Capacity Design Requirement for
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 77/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 77
SDC C & D♦ Capacity protection is required for all members that are
not participating as part of the energy dissipatingsystem
♦ Capacity protected members include:
– Superstructures – Joints and cap beams
– Spread footings
– Pile caps
– Foundations
Over-strength Capacity Design
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 78/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 78
Concepts for SDC C & D Trans. (4.11)
Minimum Support Length
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 79/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 79
Requirements (4.12)
♦ Minimum edge distance
♦ Other movement attributed to prestress shortening,
creep, shrinkage, and thermal expansion or contraction♦ Skew effect
♦ Relative hinge displacement
The calculation for a hinge seat width involves
four components:
Minimum Support Length (4.12)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 80/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 80
SDC A, B, C & D
Minimum Support Length (4.12)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 81/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 81
SDC A,B, C
LRFD - Relative Seismic Displacement
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 82/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 82
vs. Period Ratio For SDC D (4.12)
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
0 0.5 1 1.5
Ratio of Tshort/Tlong
R a t i o o f D e q
/ D m a x
Curve 1
Curve 2
Curve 3
Curve 4
♦ Deq for a target ductility of 2
shown as Curve 1
♦ Deq for a target ductility of 4shown as Curve 2
♦ Caltrans SDC shown as
Curve 3
♦ Relative hinge displacement
based on (Trocholak is et.
Al. 1997) shown as Curve 4
Table of Contents
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 83/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 83
♦ 1. Introduction
♦ 2. Symbols and Definitions
♦ 3. General Requirements
♦ 4. Analysis and Design Requirements
♦ 5. Analytical Models and Procedures
♦ 6. Foundation and Abutment Design Requirements♦ 7. Structural Steel Components
♦ 8. Reinforced Concrete Components
♦ Appendix A – Rocking Foundation Rocking Analysis
Ductility Demand on a Column or
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 84/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 84
Pier is a Function of ♦ Earthquake characteristics, including duration,
frequency content and near-field (or pulse) effects.
♦ Design force level♦ Periods of vibration of the bridge
♦ Shape of the inelastic hysteresis loop of the columns,
and hence effective hysteretic damping♦ Elastic damping coefficient
♦ Contribution of foundation and soil conditions tostructural flexibility
♦ Spread of plasticity (plastic hinge length) in the column
Plastic Moment Capacity SDC B, C
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 85/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 85
& D (8.5)♦ Moment-Curvature Analyses
♦ Expected Material Properties♦ Axial Dead Load Forces with Overturning
♦ Curve Idealized as Elastic Perfectly Plastic
♦ Elastic Portion of the Curve Pass through the point ofmarking the first reinforcing bar yield
♦ Plastic moment capacity determined from equal areas
of idealized and actual
M φ −
M φ −
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 86/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 86
Figure 8.5-1 Moment-Curvature Model
Force Demands on Capacity
P t t d M b
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 87/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 87
Protected Members(8.5-1)
where:
= idealized plastic moment capacity of reinforcedconcrete member based upon expected material
properties (kip-ft)
= overstrength plastic moment capacity (kip-ft)
= overstrength magnifier 1.2 for ASTM A 706 reinforcement1.4 for ASTM A 615 Grade 60 reinforcement
po mo p M λ =
p
po
moλ
Shear Demand & Capacity (8.6.1)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 88/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 88
♦ SDC B is the lesser of :
– Force obtained from linear elastic seismic analysis
– Force, , corresponding to plastic hinging with
overstrength
♦ SDC C and D, is the shear demand force, with the
overstrength moment and corresponding plastic
shear po
V
uV
poV
Shear Demand & Capacity (8.6.1)
’t
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 89/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 89
(8.6.1-1)
in which
(8.6.1-2)
= 0.85 for shear in reinforced concrete
= nominal shear capacity of member (kip)
= concrete contribution to shear capacity
= reinforcing steel contribution to shear capacity
con’t♦ Shear strength capacity within the plastic hinge is
based on nominal motion strength properties
n e gV V V = +
s n uV V φ ≥
sφ
nV
cV
sV
Concrete Shear Capacity SDC B, C
& D (8 6 2)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 90/103
Western Bridge Engineers’ Seminar
September 24-26, 2007 90
& D (8.6.2)(8.6.2-1)
(8.6.2-2)
If Pc is compressive then
(8.6.2-3)
Otherwise (i.e., not compression)
(8.6.2-4)
0.8e g A A=
c c eV v A=
0cv =
0.110.032 {1 }
2 0.047
cuc c
g c
f Pv f
A f α
α
⎧ ⎫′⎧ ⎫⎪ ⎪ ⎪ ⎪′ ′= + ≤⎨ ⎬ ⎨ ⎬′⎪ ⎪ ⎪ ⎪⎩ ⎭ ⎩ ⎭
Concrete Shear Capacity SDC B, C
& D (8 6 2)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 91/103
Western Bridge Engineers’ Seminar
September 24-26, 200791
& D (8.6.2)For circular columns in compression with spiral or hoop
reinforcing:
(8.6.2-5)
(8.6.2-6)
(8.6.2-7)4 sps Ae
sD=
0.3 3.67 30.15
so
f α μ ′≤ + − ≤
0.35s s yh f e f = ≤
Concrete Shear Capacity SDC B, C
& D (8 6 2)
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 92/103
Western Bridge Engineers’ Seminar
September 24-26, 200792
& D (8.6.2)For rectangular columns in compression with ties:
(8.6.2-8)
(8.6.2-9)
(8.6.2-10)vw
Ae
bs
=
0.3 3.67 30.15
w D
f α μ ′≤ + − ≤
2 0.35w w yh f e f = ≤
Column Shear Requirement (8.10)
SDC D
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 93/103
Western Bridge Engineers’ Seminar
September 24-26, 200793
SDC D
Integral Joint Shear Requirement (8.13)
SDC C and D
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 94/103
Western Bridge Engineers’ Seminar
September 24-26, 200794
SDC C,and D
Non-Integral Joint Shear Requirement
(8 13) SDC C and D
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 95/103
Western Bridge Engineers’ Seminar
September 24-26, 200795
(8.13) SDC C,and D
Presentation Topics
♦Background AASHTO LRFD Guide Specifications
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 96/103
Western Bridge Engineers’ Seminar
September 24-26, 200796
♦Background-AASHTO LRFD Guide Specifications
♦Excerpts selected from the Guide Specifications
♦AASHTO T-3 Committee recent activitiessupporting adoption as a Guide Specification
♦Current status
♦Planned activities post-adoption
♦Conclusions
AASHTO Website
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 97/103
Western Bridge Engineers’ Seminar
September 24-26, 200797
AASHTO Website
Presentation Topics
♦Background AASHTO LRFD Guide Specifications
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 98/103
Western Bridge Engineers’ Seminar
September 24-26, 200798
♦Background-AASHTO LRFD Guide Specifications
♦Excerpts selected from the Guide Specifications
♦AASHTO T-3 Committee recent activitiessupporting adoption as a Guide Specification
♦Current status
♦Planned activities post-adoption
♦Conclusions
Current Status
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 99/103
Western Bridge Engineers’ Seminar
September 24-26, 200799
♦ Completed in accordance with the AASHTO T-3Committee Recommendations
♦ Reviewed by a Technical Group and modified to meettheir state requirements
♦ Formatted to AASHTO specifications
♦ Scheduled five one-day FHWA introduction andoverview course
♦ Reviewer comments and recommendations weretabulated, reviewed and implemented or placed on a
priority list (“parking lot”) for future consideration
Outline for FHWA One-Day Overview of
AASHTO-2007 LRFD Guide SpecificationsDurationDescriptionModule
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 100/103
Western Bridge Engineers’ Seminar
September 24-26, 2007100
15Wrap-up and Summary
45LRFD Guide Spec.-Reinforced Concrete Components10
30LRFD Guide Spec.-Concrete Substructure Type 1A [SLB]9
60LRFD Guide Spec.-Concrete Substructure Type 1A [SLB]8
45LRFD – Guide Specifications-Demand Analysis [SLB]745LRFD Guide Specifications-Introduction [SLB]6
30Seismic Hazard [SLB]5
30Bridge Modeling & Analysis [SLB]4
45Structural Dynamics3
15Description of Story Line Bridge [SLB]2
45Introduction1
DurationDescriptionModule
Scheduled One-Day Seminars
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 101/103
Western Bridge Engineers’ Seminar
September 24-26, 2007101
♦Montana DOT…………...9/20/07
♦Washington DOT……....10/26/07♦Oregon DOT…………...11/14/07
♦Tennessee DOT………....1/10/08
♦Idaho DOT……………....1/31/08
Planned Activities-Post Adoption
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 102/103
Western Bridge Engineers’ Seminar
September 24-26, 2007102
♦Development of an FHWA funded trainingmanual and course geared toward practicingengineer
♦Review of the geotechnical issues addressed in
the comments and recommendations♦Address tabulated comments andrecommendations placed in a “parking lot” as
funding becomes available
Section 5.3
Conclusions
8/20/2019 Aashto Seismic Design Guidelines
http://slidepdf.com/reader/full/aashto-seismic-design-guidelines 103/103
Western Bridge Engineers’ Seminar
September 24-26, 2007103
♦ Adopted as a Guide Specifications
♦ Developed a specification that is user friendly and implemental
into production design♦ Logical progression from the current AASHTO force-basedseismic design criteria to a displacement-based criteria
♦ Technical reviewers were focused on making adjustments to bridge the gap between the seismic design approaches to easethe implementation of the displacement-based approach
♦ Computer software is available to assist the designer, Computers& Structures Inc. (CSI) is enhancing SAP 2000 to be used withthe new 2007 Guide Specifications
♦ Lets do it !!!!!!!!