# Presentation: 637987

## MAE CENTER RESEARCH SUCCESS WITH DOTsPast 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

**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

**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

**REVENUE LOSSES**
**FACILITY REPAIR COSTS***
**LIABILITY EXPOSURE**
**RESPONSIBILITY TO SOCIETY***
**Road* vs. Rail**

## 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

**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)**

## Slide 7

|  |
| --- |

## HIGHWAY INVENTORYNEW 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

**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

**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

**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

**Restrainer Cables**
**Elastomeric Bearings**
**Column and Cap Beam Wrapping**
**Micropile Additions**

## RESTRAINER  CABLES

**	****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

## RESTRAINER CABLES – TEST RESULTS

- Over 100 Restrainer Retrofits Modified by TN DOT

## 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 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 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

**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

- bearings: 252 kips

- columns: 360 kips

- crashwall: 440 kips

- cap beam: 340 kips

- pile group: 450kips

- pile cap: 380 kips

- Base shear capacity in terms of pier elements

- bearings: same

- Modified & Wrapped
- columns: 220 kips

- crashwall: same

- cap beam: same

- pile group: same

- pile cap: same

- As-built

- Retrofitted

**COLUMN CAPACITY DESIGN RETROFIT**

## COLUMN AND BEAM WRAPPING

## 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 Layer**** ****While Maintaining Vertical Load Capacity During EQ.**
**	**

## FOUNDATION IMPROVEMENT USING MICROPILES

**3 x 10 Retrofitted Pile Group**

**3x3 Retrofitted ****Pile Group**

**Case Study Foundations**

## 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

**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

**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. **