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MCEER Highway Project 094: Seismic Vulnerability of the Highway System

I.G. Buckle

Widespread highway damage  following recent major earthquakes will have a significant impact on the direction and tone of some current studies, and will be reflected in revisions to work plans and tasks in subsequent years.

Annual Report for Research Year 1
June 1, 1999 to September 30, 2000


Overview

Background

Research Needs  

MCEER Project 094

Progress and Accomplishments by Technical Area

Summary
Tasks Initiated in Research Year 1

Selected Technical Papers

Overview

This Annual Report contains a summary and synthesis of the important research results and findings obtained during the first year of research (Research Year 1) on Federal Highway Administration (FHWA) Contract DTFH61-98-C-00094, "Seismic Vulnerability of the Highway System." The work described in this report was conducted during the period June 1, 1999 to September 31, 2000.

During the summer of 1999, the Multidisciplinary Center for Earthquake Engineering Research (MCEER) initiated work on a project intended to improve the earthquake resistance of the Nation's bridges and highways. The project addresses several important areas in earthquake engineering for which there are known gaps in knowledge and technology for highways and bridges. These include tasks which are focused on the development of loss estimation technologies resulting from highway system damage; seismic analysis, design, and retrofitting of special bridge types; the application of earthquake protective system technologies for highway bridge design and retrofitting; special bridge foundation and geotechnical studies; and several unique studies and supporting activities intended to advance knowledge transfer and technology implementation.

 

Background

Surface transportation is a vital component of society. Highway transportation systems act as the key links between population centers and business sectors, and provide access to other modes of transportation. They also provide access to manufacturing plants, agricultural facilities, offices, hospitals, and residences. This network must continue to operate after an earthquake so that the lifelines of our society continue to function and emergency services can be provided to minimize the loss of life and economic distress.

Of all the components of the surface transportation system, bridges have been shown to be among the most vulnerable to earthquake damage. About 70 percent of the approximately 600,000 highway bridges in the U.S. were constructed prior to 1971, with little or no consideration given to seismic resistance. The devastating damage and loss of life resulting from recent damaging earthquakes, including the 1989 Loma Prieta, 1994 Northridge, 1995 Kobe (Japan), 1999 Chi-Chi (Taiwan), and the 1999 Kocaeli (Turkey) earthquakes, demonstrates the need to provide new and improved procedures and specifications for designing and constructing earthquake-resistant bridges and highways. Recognizing the potential to improve the performance of the Nation's highway system during and following major earthquakes, the FHWA initiated a comprehensive Seismic Research Program for bridges and highways in the fall of 1992. That program, which was effectively completed in 2000, was conducted by MCEER in cooperation with other organizations participating in the Federally-sponsored National Earthquake Hazards Reduction Program.

The research in the FHWA Seismic Research Program was performed under two FHWA contracts: DTFH61-92-C-00106, "Seismic Vulnerability of Existing Highway Construction" (known as MCEER Project 106), and DTFH61-92-C-00112, "Seismic Vulnerability of New Highways Construction" (known as MCEER Project 112). A third contract (DTFH61-98-C-00094, known as MCEER Project 094), which is the subject of this report, was initiated during the summer of 1999 in order to enhance and further advance FHWA's Seismic Research Program.

Project 106 consisted of a multi-year study concentrating on the development of state-of-practice seismic retrofit tools and guidelines that will result in cost-effective seismic evaluation and upgrading of existing highway systems and system components. Project 112 consisted of a series of special studies focused on developing improved design guidelines for new highway construction. Final products of these two studies include a two-part Seismic Retrofitting Manual for Highway Structures. These manuals are expected to be available from MCEER and the FHWA in mid 2001.

The results of these two projects has lead to significant progress in understanding and improving the seismic performance of highway bridges and systems. Improved standards and codes developed under this and other State and National seismic research studies and programs have been shown to be effective, as recent earthquakes have demonstrated that structures built to these standards indeed perform better than those built to earlier standards. Despite this progress, however, there are still areas in need of further research before seismic-resistant highway systems are a reality.

 

Research Needs 

There are presently many gaps of knowledge that should be addressed in order to make the Nation's highway infrastructure less seismically vulnerable.  MCEER Project 094 focuses on several important topics as described below. 

Although a significant amount of effort and resources have been expended over the past 20 years on the seismic design and performance of highway bridges, some classes of bridges have yet to be studied; among these are long span bridges, large truss structures, and bridges on difficult sites.  Some of these structures are very old and may have piers of unreinforced masonry or members consisting of non-ductile steel or cast iron.  Their seismic resistance is difficult, if not impossible, to quantify in a generic manner given the current state of bridge engineering knowledge.  This is a major concern because these structures are usually critically important to the region they serve, and society expects a higher level of performance from these structures than for more conventional highway structures.  For many of these structures, any loss of access due to an earthquake will have a major impact on emergency services and impede post-earthquake recovery.  Despite the importance of these structures, little is known about their capacity for extreme loads, as would be expected during an earthquake.

 

The high cost of retrofitting the Nation's bridges is a major disincentive to bridge owners who are faced with extensive improvement programs.  A more intelligent way of prioritizing a bridge inventory and selecting bridges to be retrofitted is necessary to ensure that scarce resources are used in the most cost-effective manner.  For this reason, the FHWA sponsored MCEER to develop an advanced seismic risk assessment procedure for highway systems under Project 106.  This system determines direct bridge damage losses and costs, and predicts traffic flow impacts due to bridge-related damage caused by scenario earthquakes.  To reach its full potential, however, the risk assessment methodology will need to be extended to include the determination of indirect costs and impacts, and to include the effects of damage to other components of a highway system, such as tunnels, slopes, pavements, and retaining structures.  Under Project 106, the methodology for seismic risk assessment of highway systems was developed and demonstrated, and a preliminary computer software package was developed.  Under Project 094, the methodology and software will be calibrated against actual earthquake experience data and validated through the application of case studies and experiential comparisons.  In addition, the software will be refined and made more "user friendly," and the methodology will be extended to enhance it's loss estimation capabilities.

 

Improved retrofit technologies can provide more efficient and less costly options to bridge owners, and may reduce the overall cost of retrofit projects to more acceptable levels.  Earthquake protective systems offer promise in this regard and several states have implemented passive protective system technologies in a limited manner.  However, the cost and uncertain reliability of these devices is still a barrier to their widespread application.  Smart materials have recently been developed and new insights into adaptive technologies for subassemblages and complete structures offer potential solutions to this problem.  Applications to long-span bridges are particularly attractive since there should be a significant cost reduction over standard strength-based retrofitting options and seismic performance can be improved to a level where closure or restricted access could be avoided.

 

Many bridges are located on weak soils, and soil-foundation-structure interaction in an earthquake is a complex phenomenon that represents a large gap of knowledge in the earthquake engineering field.  Despite many years of effort, progress in this topic has been slow and often project or site-specific.  Project 094 will address some of these concerns in a focused and multi-disciplinary manner.

 

Also, the need for knowledge and technology transfer can not be overemphasized.  Codes, guidelines, and manuals for design professionals are becoming increasingly complex as the state-of-the-art in earthquake engineering changes.  Engineers need clear, concise, and authoritative guidance in this rapidly growing field.

 

 

MCEER Project 094

In response to these issues, the FHWA structured MCEER Project 094 to address a range of topics in these areas. The project also provides the opportunity to address several special studies, and to adjust to changing needs as new knowledge is obtained from recent earthquakes.

MCEER Project 094 has six major technical tasks:

The structure of Project 094 is shown in Figure 1. The overall study is intended to supplement and address a number of earthquake engineering highway system issues and problems not covered in previous FHWA sponsored research projects. The program has a national focus and consists of a mix of analytical and experimental studies, which will result in a number of manuals, guides, and design and retrofitting recommendations for evaluating and improving the seismic resistance of highway systems and system components.


Figure 1. MCEER Project 094 Management Structure and Project Tasks

 

Progress and Accomplishments by Technical Area

A number of research tasks were initiated during Research Year 1; these are summarized in Table 1. The following is a brief overview of the progress and accomplishments that have been made under the research areas of this contract. More detail on selected tasks initiated during Research Year 1 is included in Part II of this report.

Task B, Loss Estimation Methods for Highway Systems - During Year 1, researchers focused on validating the Seismic Risk Analysis (SRA) software that was developed by MCEER researchers under Project 106. The SRA software estimates post-earthquake damage states for a highway system or regional network, based on various input scenario earthquakes. The software computes how the damage will impact the capacity of the local highway network; and then calculates economic losses (primarily direct losses, although some estimates of indirect losses related to detour lengths and delay times are also determined). The validation of the software includes running the software for the Northridge and Whittier Narrows earthquakes to determine if the software estimates losses similar to the actual losses incurred during these two earthquakes.

Selected accomplishments during Research Year 1 in this topic area include:

Task C, Seismic Design and Retrofit Manual for Special Bridges - A series of studies is being conducted in three primary areas for special bridges: (a) research on geotechnical and foundation problems; (b) research on structural details and problems; and (c) development of an assessment and retrofitting manual for special bridge types. The research under this task is aimed at narrowing gaps in knowledge of seismic design and performance of special bridge types including long-span suspension and cable-stayed bridges, arch, and truss structures, to enable the development of a comprehensive retrofitting manual for these bridge types.

Selected accomplishments during Research Year 1 in this topic area include:

Task D, Earthquake Protective Systems - A series of studies were initiated in order to review the past performance of earthquake protective systems that had been employed on bridges which were subjected to recent earthquakes, to extend the state-of-the-art in hardware technology, and to produce design aids for the application of earthquake protective systems in new and retrofit designs.

Selected accomplishments during Research Year 1 in this topic area include:

Task E, Foundation and Geotechnical Studies - Three studies were initiated in Research Year 1 in an attempt to better understand the behavior and performance of soils and highway bridge foundations under strong ground motion. Soil-foundation-structure interaction in an earthquake is a complex phenomenon that still has many unknowns. Research under this task is aimed at narrowing this gap in knowledge and to devise appropriate design and retrofit strategies.

Selected accomplishments during Research Year 1 in this topic area include:

Tasks F and G, Special Studies and Technology Exchange and Transfer - Several studies were initiated in this research area to address specific needs regarding seismic issues in the bridge and highway engineering communities. These include assessing non-destructive evaluation technologies that can be used to assess the post-earthquake capacity and performance of retrofitted or damaged structures; providing technical support for the installation of a seismic-performance monitoring system on a major cable-stayed bridge being constructed across the Mississippi River; assisting in the development of new seismic design specifications which are being prepared under the AASHTO-sponsored NCHRP Project 12-49; involvement in earthquake reconnaissance following several major earthquakes which occurred during Research Year 1; and organizing and hosting several workshops on bridge seismic design and performance.

The Task F special studies conducted during Research Year 1 include the following:

Among Task G Technology Exchange and Transfer activities that were conducted during Research Year 1 are the following:

The third workshop was held in Ankara, Turkey and focused on lessons learned during the 1999 Kocaeli and Duzce earthquakes in Turkey. MCEER provided support for several bridge engineering practitioners who participated in the workshop, which was jointly organized by the FHWA, Turkish General Directorate of Highways and Turkish Road Association. The discussions held during this workshop focused on the seismicity of the North Anatolian Fault system, which earth science researchers believe is very similar in size and potential fault rupture energy as the San Andreas fault in California, and the performance of bridges, tunnels, and earthquake protective systems during these earthquakes.

 

Summary

Research Year 1 on MCEER Project 094 was an active time during which a number of important research tasks were initiated. Major earthquakes that occurred during the Research Year have had significant impacts on the direction and tone of some of the initial studies, and will be reflected in revisions to work plans and tasks in subsequent years.

Part II of this Annual Report consists of technical papers describing the research approach and preliminary results of selected Year 1 research tasks.

 

Tasks Initiated in Research Year 1

 

Task/Area

Title

Investigator(s)

Inst(s)

TASKS A & H - Project Administration and Reporting

A

Project Administration & Support for the HSRC

G. Lee

MCEER

H

Project Reporting

G. Lee

MCEER

TASK B - Loss Estimation Methods for Highway Systems

   

B1-1

Review of REDARS Seismic Risk Analysis Software

R. Eguchi

ICI

B1-2

Support for Review and Extension of REDARS Software

S. Werner

SSEC

TASK C - Seismic Design and Retrofit Manual for Special Bridges

C1-1

State-of-Practice Survey and Strawman Seismic Design and Retrofit Manual

C Seim

TYL

C2-1

Long Period Ground Motions and Spatial Variation Review

A. Papageorgiou

SUNY

C2-2

Pile Group Effects

P. Lam

G. Martin

EMI

USC

C3-1

Steel Truss Bridge Braced Pier and Substructure Connection Behavior

M. Bruneau &

J. Mander

SUNY

TASK D - Earthquake Protective Systems

D1-1

Performance Review of Seismically Isolated Structures

G. Lee

SUNY

D1-2

Theoretical Formulations for Highly Damped Bridge Systems

Z. Liang &

G. Lee

SUNY

D2-1

Intelligent Bearings - State-of-the-art Review

G. Lee &

M. Constantinou

SUNY

D3-1

Manual for the Design and Retrofit of Bridges with Earthquake Protective Systems

M. Constantinou

I. Buckle

SUNY

UNR

TASK E - Foundation and Geotechnical Studies

E1-1

Behavior and Displacement Capacity of Pile and Pile-to-Cap Connections

J. Mander

Y. Xiao &

G. Martin

SUNY

USC

E1-2

Foundation Design for Liquefaction-Induced Lateral Displacements

G. Martin

USC

E2-1

Ground Remediation for Silty Soils Using Stone Columns

S. Thevanayagam

SUNY

TASK F - Special Studies

F1-1

Post-Earthquake Assessment of Retrofitted Bridges - Technology Review

J. Mander

SUNY

F2-1

Design and Implementation of Seismic Instrumentation for the Cape Girardeau Cable-Stayed Bridge

M. Celebi

N. Jones

USGS

Consult.

F2-2

Hardware Acquisition for the Cape Girardeau Cable-Stayed Bridge

G. Lee

MCEER

F3-1(a)

Parameters Studies and Design Impacts

R. Mayes &

R. Nutt

Consult.

F3-1(b)

Geotechnical Performance Criteria Workshop

G. Martin &

D. Anderson

USC

CH2M

F3-1(c)

Steel Workshop in Support of NCHRP 12-49

M. Bruneau

MCEER

F4-1

Earthquake Reconnaissance

G. Lee

MCEER

TASK G - Technology Exchange and Transfer

G2-1

3rd FHWA National Seismic Conference on Bridges and Highways

M. Higgins

MCEER

G3-1

1st International Workshop on Mitigation of Seismic Effects on Transportation Structures

J. Penzien

ICEC

G3-2

2nd International Workshop on Mitigation of Seismic Effects of Transportation Structures

I. Buckle

UNR

G3-3

International Workshop on Lessons Learned from Recent Earthquakes- KGM/FHWA U.S.-Turkey Workshop

M. Higgins

MCEER

 

INSTITUTION CODES
CH2M CH2M Hill International
EMI  Earth Mechanics Inc.
ICEC International Civil Engineering Consultants
ICI  ImageCat Inc.
MCEER  Multidisciplinary Center for Earthquake Engineering Research
SSEC Seismic Systems & Engineering Consultants
SUNY State University of New York at Buffalo
TYL T.Y. Lin International
UNR University of Nevada, Reno
USC  University of Southern California
USGS  US Geological Survey


Selected Task Technical Papers

Ronald T. Eguchi, ImageCat, Inc.
Task B1-1 Review of REDARS 1.0 Seismic Risk Analysis Software (will open in a new window)

Charles Seim, T.Y. Lin International
Task C1-1 Seismic Design and Retrofit Manual for Long-Span and Special Bridges (will open in a new window)

Geoffrey R. Martin, University of Southern California and Ignatius Po Lam, Earth Mechanics, Inc.
Task C2-2 Pile Group Effects (will open in a new window)

Michel Bruneau, MCEER and University at Buffalo, John Mander, University at Buffalo
Task C-3-1  Steel Truss Bridge Braced Pier and Substructure (will open in a new window)

George C. Lee, MCEER and University at Buffalo, Zach Liang, University at Buffalo
Task D1-1  
Task D1-2
 
Task D2-2
  Performance and New Concepts for Earthquake Protective Systems (will open in a new window)

Yan Xiao and Geoffrey Martin, University of Southern California
Task E1-1 Behavior and Displacement Capacity of Pile and Pile-to-Cap Connections (will open in a new window)

Geoffrey Martin, University of Southern California
Task E1-2  Foundation Design for Liquefaction Induced Lateral Displacements (will open in a new window)

S. Thevanayagam, University at Buffalo and Geoffrey Martin, University of Southern California
Task E2-1 Liquefaction and Post-Liquefaction Dissipation/Densification Characteristics of Silty Soils (will open in a new window)

Richard V. Nutt and Ronald L. Mayes, Consultants
Task F3-1(a) Comparison of Typical Bridge Columns Seismically Designed with and without Abutment Participation Using AASHTO Division I-A and Proposed AASHTO LRFD Provisions (will open in a new window)

 


Overview

Background

Research Needs

MCEER Project 094

Progress and Accomplishments by Technical Area

Summary

Tasks Initiated in Research Year 1

Selected Technical Papers

 

 

 


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