Mae center research success with dots past and future
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MAE CENTER RESEARCH SUCCESS WITH DOTs Past and Future. Neil M. Hawkins - Professor Emeritus University of Illinois MAE Center Annual Meeting - 2002.

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Mae center research success with dots past and future
MAE CENTER RESEARCH SUCCESS WITH DOTsPast and Future

Neil M. Hawkins - Professor Emeritus

University of Illinois

MAE Center Annual Meeting - 2002

With sincere appreciation of the contributions of Professors DeRoches and French (Georgia Tech), Aschheim, LaFave and Long (Illinois), Hwang (Memphis), and personnel from GaDOT, IDOT and TDOT and Caltrans


Organization of presentation
ORGANIZATION OF PRESENTATION

  • BACKGROUND – Lifeline Considerations for Transportation Systems

  • BACKGROUND – The Highway System Lifeline

  • OVERVIEW OF MAE TRANSPORTATION

    RESEARCH ACTIVITIES AND SUCCESSES

  • VISION FOR FUTURE


The transportation system as a lifeline
THE TRANSPORTATION SYSTEM AS A LIFELINE

  • DESIGN REQUIRES CONSIDERATION OF FACTORS DIFFERING FROM THOSE FOR BUILDINGS

  • ACCEPTABLE PERFORMANCE DEPENDS ON:

    • Functionality of System after Event and Not Life Safety During Event

    • Financial Impact of Event


Financial impacts
FINANCIAL IMPACTS

  • REVENUE LOSSES

  • FACILITY REPAIR COSTS*

  • LIABILITY EXPOSURE

  • RESPONSIBILITY TO SOCIETY*

  • Road* vs. Rail


The highway system lifeline
THE HIGHWAY SYSTEM LIFELINE

  • SPACIALLY DISTRIBUTED COMPONENTS

    INTERCONNECTED OPERATIONALY AND PHYSICALLY

  • REDUNDANCY ALLOWS SOME LEVEL OF LOCAL DAMAGE

  • AGENCY’S JURISDICTION DETERMINES ITS RESPONSIBILITIES

  • SEISMIC HAZARD DEFINED BETTER BY SCENARIO EVENT THAN PROBABILISTIC GROUND MOTION


Highway lifeline system design
HIGHWAY LIFELINE SYSTEM DESIGN

  • PERFORMANCE GOALS FOR SCENARIO EARTHQUAKE – 2 Rather than 1.5 on Estimated Ground Motions?

  • IDENTIFICATION AND QUANTIFICATION OF HAZARD – Soil Liquefaction, Permanent Ground Deformations, Structural Movements and Failures, and Importance of EQ Event Relative to Other Hazards.

  • ASSESS DAMAGE STATE FOR SCENARIO EVENT

    Functionality of Components, Time and Cost to Repair.

  • EVALUATE SYSTEM FUNCTIONALITY- IDENTIFY RISK REDUCTION OPTIONS (CBE)


Highway inventory new madrid seismic zone
HIGHWAY INVENTORYNEW MADRID SEISMIC ZONE

  • CHARACTERISTICS OF SYSTEM WITHIN AREA WITH 0.1g ACCELERATION FOR 500 YEAR RETURN PERIOD

  • Age for 90% of Bridges

    Interstate 1966 + - 8 years

    Overpass 1963 + - 8years

  • Type of Bridge

    2/3rds Continuous

    Steel : Concrete

    4:1Overpasses

    1:1 Interstate

    NBI Lacks Information on Bearing, Bent, Foundation, and Soil Characteristics

    Interstate Bridge Characteristics Different to Secondary Road


Highway inventory illinois south of i 70
HIGHWAY INVENTORYILLINOIS SOUTHOF I-70

  • BRIDGE CHARACTERISTICS VERY DIFFERENT TO CALIFORNIA BRIDGES. PIERS NOT INTEGRAL WITH BEAMS OR DECK.

  • 533 Bridges on Primary Emergency Routes (Interstates)

  • For 10% Sample:

    2/3rds Steel Continuous

    Support Type:

    50% Multi-Col. Pier

    40% Wall-Pier

    90% of Foundations Pile Supported

    30% on Soil Likely to Liquefy


Vulnerability functionality relationships
VULNERABILITY-FUNCTIONALITYRELATIONSHIPS

  • EXPERT OPINION -“EMPIRICAL” RELATIONSHIPS – HAZUS

  • ANALYTICAL RELATIONSHIPS

  • Approach Slabs

  • Major River Crossing

  • Pavement

  • “Standard” Bridge

  • EQ with 10% probability in 50 years causes little structural damage to as-built interstate bridges.

  • EQ with 2% probability in 50 years causes wide damage to steel bearings, columns and foundations


Damage types
DAMAGE TYPES

BRITTLE

  • Bearing or Pedestal Failure

  • Beam or Column Shear Failure

  • Column Lap Splice

  • Pile Shear or Pullout

DUCTILE

  • Bearing Overturning

  • Excessive Pier Drift

  • Excessive Ground Displ.

  • Pile Flexure


Retrofit strategies
RETROFITSTRATEGIES

  • Restrainer Cables

  • Elastomeric Bearings

  • Column and Cap Beam Wrapping

  • Micropile Additions


Restrainer cables
RESTRAINERCABLES

Restrainer Cables are used to ensure that bridge beams movements relative to the bearings are restricted and beams cannot displace off bearings longitudinally or transversally.



RESTRAINER CABLES – TEST RESULTS

Over 100 Restrainer Retrofits Modified by TN DOT


Elastomeric bearings
ELASTOMERIC BEARINGS

  • Allows for Temperature Effects. While Bearings Compress Little They Deform Easily in Shear.

  • Hysteresis Small W/o Slip at Interface and Large with Slip.

  • Are Hysteresis Characteristics Advantageous for EQ Effects?

  • Does Stiffening of Elastomer with Decreasing Temperature Obviate Beneficial Effects for EQ?


Elastomeric bearings1
ELASTOMERIC BEARINGS

  • Tests Conducted on New and Used Bearings to Find Changes in Slip, Stiffness and Hysteretic Characteristics with Decreasing Temperature and Increasing Cyclic Deformations.

  • Dynamic Analyses Made For Typical 3 Span Bridge with Fixed Bearing at Central Pier and Elastomeric Type II Bearings at Side Piers and Type I at Abutments.


Elastomeric bearings2
ELASTOMERIC BEARINGS

  • Temperature Effect Unpredictable. Vary Widely with Materials Used by Manufacturer

  • Elastomeric Bearing Use Can Reduce or Increase Pier Forces. Type and Location Must Be Properly Selected.


Column and beam wrapping
COLUMN AND BEAM WRAPPING

  • Prevents Shear and Lap Splice Failures and Increases Flexural Ductility Capacity.

  • Steel or Composite Placed as Bands or as Encasement. Effectiveness Varies with Form and Quality Control.

  • Encasement More Aesthetically Pleasing But Results in Accelerated Deterioration if Located Below Deck Joint.

  • Effective on Deteriorated Members if Member Properly Repaired First.


Column capacity design retrofit
COLUMN CAPACITY DESIGN RETROFIT

bearings: 252 kips

bearings: same

cap beam: 340 kips

cap beam: same

Modified & Wrapped

columns: 220 kips

columns: 360 kips

crashwall: 440 kips

crashwall: same

pile cap: 380 kips

pile cap: same

pile group: 450kips

pile group: same

Retrofitted

As-built

Base shear capacity in terms of pier elements



Foundation improvement with micropiles
FOUNDATION IMPROVEMENT WITH MICROPILES

  • To Increase Foundation Capacity or Stiffness

  • To Resist Overturning Where Existing Cap to Pile Connections Are Inadequate

  • To Extend Piles Below Liquefiable LayerWhile Maintaining Vertical Load Capacity During EQ.


Foundation improvement using micropiles
FOUNDATION IMPROVEMENT USING MICROPILES

Case Study Foundations

3 x 10 Retrofitted Pile Group

3x3 Retrofitted Pile Group


Foundation improvement using microplies
FOUNDATION IMPROVEMENT USING MICROPLIES

  • Stiffness Increased 50% with 3x3 Pile Addition.

  • Even With Retrofit Liquefaction Near Surface Substantially Reduced Pier Lateral Stiffness.

  • Dynamic Rotational Stiffness Increased Regardless of Which Soil Layer Liquefied.

  • Stiffness in Field Tests Less Than Predicted


Vulnerability functionality for mid america bridges
VULNERABILITY- FUNCTIONALITY FOR MID-AMERICA BRIDGES

  • Methodology to Derive Relationships, Repair Costs and Recovery Time Developed By Hwang (Memphis).

  • Response of Typical Multi-Span Bridge Controlled by Response of Central Pier.

  • Vulnerability Functions Derived for “Standard” Bridge for Longitudinal (GaTech) and Transverse Directions (UIUC)


Vision for future
VISION FOR FUTURE

  • Consensus Criteria Developed for CBE and Performance Based Design of EQ Emergency Routes in NMSZ Using FHWA Pooled Funds.

    - Design All New, and Systematically Upgrade All Existing, Major River Crossings and Their Approaches to AASHTO-LRFD Seismic Criteria.

    - Identify Life Safety Needs of Communities and Design and Upgrade Routes Consistent with Those Needs.

    - Design Other New Structures, and Upgrade Other Existing Structures, to EQ with 10 % PE in 50 years.

  • MAEC Has Developed The Tools and Skilled Personnel

    to Successfully Complete That Task.


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