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Strength and Ductility of Reinforced Concrete Highway Bridge Pier

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Title: DEVELOPMENT OF A RHEOLOGY MODEL FOR LAMINATED RUBBER BEARINGS Author: Bhuiyan Last modified by: user Created Date: 3/27/2009 9:46:03 AM Document presentation ... – PowerPoint PPT presentation

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Title: Strength and Ductility of Reinforced Concrete Highway Bridge Pier


1
Strength and Ductility of Reinforced Concrete
Highway Bridge Pier
  • Engr. Md. Abdur Rahman Bhuiyan, PhD
  • Associate Professor
  • Department of Civil Engineering
  • Chittagong University of Engineering and
    Technology
  • Chittagong-4349

National Seminar on Performance Based Design of
Reinforced Concrete Structures Organized
by Bangladesh Steel Re-Rolling Mills
(BSRM) Venue Chittagong Club Auditorium,
Chittagong
2
Introduction
  • Highway bridges are the most common and critical
    civil infrastructure components of a
    transportation network as they play important
    role in
  • evacuation and emergency routes for
  • rescues,
  • first-aid,
  • firefighting,
  • medical services and
  • transporting disaster commodities

during and after the earthquake
3
Introduction (contd)
  • The recent earthquakes, such as
  • the 1994 Northridge earthquake,
  • the 1995 Great Hanshin earthquake ,
  • the 1999 Chi-Chi earthquake,
  • the 2008 Sichuan earthquake,
  • the 2010 Chile earthquake, and
  • the 2010 Haiti earthquake,
  • have shown the inadequacy of strength of the
    existing structures against earthquake effects

4
Damage Scenario
Shear Failure of flared column in the 1994
Northridge earthquake
Flexural failure at the base of bridge pier of
the Hanshin expressway in the 1995 Kobe earthquake
Bond failure of lap slices of bridge pier in the
Loma Prieta earthquake in 1989
Unseating of simply supported link span in the
1995 Kobe earthquake
5
Damage Scenario (contd)
Failure of flexural plastic hinges in bridge
piers in the 1994 Northridge earthquake
Flexural-shear failure at pier midheight in the
1995 Kobe earthquake
Collapse of the Hanshin expressway in the 1995
Kobe earthquake
Shear Failure of flared column in the 1994
Northridge earthquake
6
Damage Scenario at a glance
  • flexural failure of piers of the Hanshin
    Expressway in the Kobe earthquake in 1995
  • bond failure at the base of a RC columns
    attributable to lap slice in the Loma Prieta
    earthquake in 1989
  • the flexure-shear failure of bridge piers
    initiated at bar cutoff locations around the pier
    mid-height level in the 1995 Kobe earthquake
  • shear failure of columns in the 1994 Northridge
    earthquake

7
Philosophy of Seismic Design of RC Bridges
  • Basic concept of design philosophy and seismic
    performance criteria are more or less similar
    among seismic codes in Japan, the USA, the EU and
    New Zealand and some other countries that
  • for small-to-moderate earthquakes, bridges
    should be resisted within the elastic range of
    structural components without significant damage,
  • bridges exposed to moderate to strong
    earthquakes should not collapse

8
Development of Seismic Design Specification of
Highway Bridge
1926 Design Specification
  • The first seismic provisions for highway
    bridges were introduced in 1926 after destructive
    damage of the 1923 Great Kanto earthquake
  • It only specified a seismic lateral force of
    20 of the gravity force no other
    seismic-design-related provisions were given in
    this specification

9
Development of Seismic Design Specification of
Highway Bridge (contd.)
1971 Design Specification
  • The first comprehensive seismic design
    provisions were issued by the Ministry of
    Construction in 1971 in the form of the Guide
    Specification for Seismic Design of Highway
    Bridges
  • It was specified in the 1971 Specification that
    the lateral force shall be determined depending
    on seismic zone, importance and ground condition

10
Development of Seismic Design Specification of
Highway Bridge (contd)
1980 Design Specification
  • The 1971 Guide Specification for Seismic Design
    were revised in 1980 to become the Design
    Specification for Highway Bridges

11
Development of Seismic Design Specification of
Highway Bridge (contd)
1990 Design Specification
  • The 1980 Design Specification was revised in
    1990
  • Various major revisions were included in the
    revised version by incorporating the ductility
    method as a checking tool

12
Development of Seismic Design Specification of
Highway Bridge (contd)
1995 Design Specification
  • Forty days after the Hyogo-ken nanbu (H-k-n)
    earthquake, the Japan Ministry of Construction
    issued the Guide Specification for reconstruction
    and repair of highway bridges which suffered
    damage in the (H-k-n) earthquake (1995
    Specification) for use in the reconstruction of
    the damaged bridges

13
Development of Seismic Design Specification of
Highway Bridge (contd)
1996 Design Specification
  • Although the 1995 and 1996 Specifications are
    essentially the same in concept, modifications
    and upgrading were included in the 1996
    Specification, most importantly, the check on the
    Ductility was upgraded to the Ductility Design
    method

14
Development of Seismic Design Specification of
Highway Bridge (contd)
2002 Design Specification
  • Because of the unsatisfactory performance of
    bridges in the 1995 Kobe earthquake, the Japanese
    Design Specifications of Highway Bridges was
    revised in 1996.
  • The code was further revised in 2002 based on
    the Performance-based design concept for the
    purpose to respond the international
    harmonization of design codes and the flexible
    employment of new structures and new construction
    methods

15
Performance Based Design
  • Design for seismic resistance has been
    undergoing a critical reappraisal in recent
    years, with the emphasis changing from strength
    to performance.
  • For most of the past 70 years the period over
    which specific design calculations for seismic
    resistance have been required by codes strength
    and performance have been considered to be
    synonymous.
  • However, over the past 25 years there has been
    a gradual shift from this position with the
    realization that increasing strength may not
    enhance safety, nor necessarily reduce damage.

16
Performance Based Design (contd.)
The performance-based design concept is that the
necessary performance requirements and the
verification policies are to be clearly specified
17
Performance Based Design (contd.)
  • The performance-based design distinguishes itself
    from the conventional design approach by
    specifying
  • Objectives (or Goals) and Functional Requirements
    (Functional Statements), which are qualitative,
    and
  • specifying or referencing Performance
    Requirements (or Criteria)
  • can be used to assess whether or not the
    Objectives have been met

18
Performance Based Design (contd.)
Hierarchy of performance-based design
19
Seismic Performance Criteria (JRA, 2002)
  • the Level 1 earthquake is the moderate ground
    motion with high probability of occurrence and
  • the Level 2 Earthquake is strong ground motion
    with low probability to occur
  • Type I earthquake the Kanto earthquake
  • Type II earthquake the Kobe earthquake

20
Seismic Performance Criteria (ATC 32)
Ground Motion (GM) Service level Service level Damage level Damage level
Ground Motion (GM) Ordinary Bridges Important Bridges Ordinary Bridges Important Bridges
Functional evaluation GM Immediate Immediate Repairable Damage Minimum damage
Safety evaluation GM Limited Immediate Significant damage Repairable damage
In service level, immediate implies full access
to normal traffic almost immediately following
the earthquake, and limited implies that
limited access (reduced lanes, and light
emergency traffic) is possible within days of the
earthquake, and that full service is restorable
within months.
  • Specifications for highway bridge seismic
    design part V, Japan Road Association, 2002
  • Applied Technology Council (ATC-32), 1996

21
Verification Methods of Seismic Performance
It is the fundamental policy of the verification
of seismic performance that the response of the
bridge structures against design earthquake
ground motions does not exceed the determined
limit states.
22
Structural Deformation Capacity (AASHTO-LRFD)
23
Failure mode, lateral strength and ductility
capacity of a bridge pier
  • The pier strength and the design ductility
    factor of pier can be determined based on the
    failure mode

Pe
Py Pu
Dy
Dm
flexural failure
shear failure after flexural yielding
shear failure
24
Failure mode, lateral strength and ductility
capacity of a bridge pier (contd..)
The allowable lateral capacity
is provided as
flexural failure shear failure after flexural
damage
shear failure
is provided as
The allowable displacement ductility
flexural failure
shear failure after flexural damage and shear
failure
is safety factor depending upon bridge
importance and type of earthquake ground motion ,
are yield and ultimate displacement of the bridge
pier under earthquake ground motion
and
25
Evaluation of Lateral Strength and Ductility of
RC Bridge Pier
The cross-section of the pier is 7 m 1.9 m
The height of the pier is 11.5 m
The weight of the superstructure and pier are,
respectively, 990 tonf and 347 tonf .
26
Evaluation of Lateral Strength and Ductility of
RC Bridge Pier (contd)
Using the moment-curvature plot shown in Figure
(left) and the Equation presented below, the top
displacement of the bridge pier can be obtained
Finally, the force-displacement relationship at
top of the bridge can be obtained from which the
lateral strength and ductility capacity of the
bridge pier can be evaluated.
27
Evaluation of Lateral Strength and Ductility of
RC Bridge Pier (contd)
Moreover, a professional software (for example,
Seismostruct 2011) can be used to derive the
force-displacement relationship at top of the
bridge pier by conducting push-over analysis
28
Seismic Performance of a reinforced concrete
bridge pier under strong seismic event
29
Ductility of RC Structures
  • Material Ductility
  • Curvature (section) Ductility
  • Element Ductility
  • Structural Ductility

30
Material Ductility
31
Material Ductility
32
Curvature Ductility
33
Curvature Ductility
34
Element Ductility
35
Element Ductility
36
Element Ductility (Column)
37
Structural Ductility (Frame)
38
ACI 318-02 special provisions for seismic design
of RC structures
Goal
  • to ensure adequate ductility under inelastic
    displacement reversals brought on by earthquake
    loadings

How to achieve the goal?
  • this goal can be achieved by providing concrete
    confinement and inelastic rotation capacity in RC
    structures

Maintain the minimum ratio of tensile strength to
yield stress of reinforcing bars
Use of seismic hook on stirrups, hoop and
crossties, etc.
39
Thank you very much
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