SUMMARY REPORT OF THENCHRP 20-68A US Domestic Scan Program

Scan 11-02: Best Practices Regarding Performance of Accelerated Bridge Construction (ABC) Connections in Bridges Subjected To Multi-

Hazard and Extreme Events

Presented by:Alexander K. Bardow, P.E.

State Bridge EngineerMassachusetts Department of Transportation

SPECIAL NOTESPECIAL NOTESPECIAL NOTESPECIAL NOTE: The work described in this document was conducted as part of NCHRP Project

20-68A, the U.S. Domestic Scan program. This program was requested by the American Association of State Highway and Transportation Officials (AASHTO), with funding provided through the National Cooperative Highway Research Program (NCHRP). The NCHRP is supported by annual voluntary contributions from the state departments of transportation. Additional support for selected scans is provided by the U.S. Federal Highway Administration and other agencies.

This report IS NOT an official report of the National Cooperative Highway Research Program, Transportation Research Board, National Research Council, or The National Academies. This report was prepared by the scan team for Scan 11-02 Best Practices Regarding Performance of Accelerated Bridge Construction (ABC) Connections in Bridges Subjected To Multi-Hazard and Extreme Events, whose members are listed herein. Scan planning and logistics are managed by Arora and Associates, P. C.; Harry Capers is the Principal Investigator. NCHRP Project 20-68A is guided by a technical project panel and managed by Andrew C. Lemer, Ph.D., NCHRP Senior Program Officer.

Scan Team Members

Scan Team Chair: Jugesh Kapur, PE, SE,Washington State DOT

Scan Team Members:Alexander K. Bardow, PE, Mass DOTWaseem Dekelbab PhD, PE, TRBMichael Keever, CaltransM. Saiid Saiidi*, PhD, PE, University

of Nevada, RenoJoshua Sletten, SE, Utah DOTDan Tobias, PhD, SE, Illinois DOTW. Phillip Yen, PhD, PE, FHWA

*Subject Matter Expert preparing reports and presentations

ObjectiveObjectiveObjectiveObjective

Identify connection details that are used in the United States for ABC and which have performed well under extreme events, natural or man-made, such as waves and tidal action or storm-surges, seismic events, blast, and other large forces.

Scan Team Events

Several conference calls prior, in between, and subsequent to scans

Desk Scan Organizational meeting: November 17,

2011

Desk Scan ObjectiveDesk Scan ObjectiveDesk Scan ObjectiveDesk Scan Objective

Further the efforts of the full scan team in acquiring information of value to the transportation community.

Increase the cost-effectiveness of a full scan by advising a team where best to commit its time during travel

Help to refine the scope of the scan by identifying relevant sources of information around the country and narrowing the focus of the scan as needed.

Desk Scan TasksDesk Scan TasksDesk Scan TasksDesk Scan Tasks

Summary review of the most relevant reports, papers, and web materials

Collect and organize amplifying questions from scan team members

Extensive survey of nine states with one or more extreme events and a known history of activities and interest in ABC

Summarize desk scan findings in a report Recommend list of states and institutions to be

visited or included in the scan through conference calls

Organizational Meeting Organizational Meeting Organizational Meeting Organizational Meeting Nov. 2011Nov. 2011Nov. 2011Nov. 2011 Refined and finalized amplifying questions Finalized list of states and institutions to be visited

or participate through conference calls Week 1: March 25-31, 2012

Visit Massachusetts* and Florida DOTs;Web conference participation by University of Buffalo and Texas

and S. Carolina DOTs

Week 2: April 22-28, 2012Visit Utah, Washington*, and Nevada DOTs; Caltrans engineers/researchers participation while team meets in

NevadaVisit University of Washington, Seattle, and University of

Nevada, Reno, laboratories

* Several bridge site visits in Massachusetts and Washington

Scan Meeting ParticipantsScan Meeting ParticipantsScan Meeting ParticipantsScan Meeting Participants

DOT Management Officials

Engineers Contractors Fabricators Suppliers Researchers at

selected institutions studying ABC connections under extreme events

Summary of Amplifying QuestionsSummary of Amplifying QuestionsSummary of Amplifying QuestionsSummary of Amplifying Questions

General Issues on Design for Multi-Hazard Loading

ABC Design for Multi-Hazard Loading Decision and Design Tools for ABC Use Past ABC Application Partnership with Industry and Research

Institutions ABC Inspection and Maintenance

Summary of Initial FindingsSummary of Initial FindingsSummary of Initial FindingsSummary of Initial Findings

8 Topic Areas:1. Extreme load consideration for bridges and

ABC connections 2. ABC connection details3. ABC connection maintenance4. Standardization of ABC connection details

and processes5. ABC connection research6. Innovative ABC connections7. Monitoring ABC connections and

prefabricated bridge elements and systems8. Other findings

1 1 1 1 ---- Extreme Load Consideration Extreme Load Consideration Extreme Load Consideration Extreme Load Consideration

for Bridges and ABC Connections for Bridges and ABC Connections for Bridges and ABC Connections for Bridges and ABC Connections

MH load combination considered only to a limited extent even in conventional bridges due to limited guidance and because of low probability of simultaneous occurrence

No information specific to ABC connection design under MH loading

Despite maturity of seismic design of conventional bridges, no AASHTO seismic design guidelines for ABC.

Current AASHTO Guide restriction on splicing in SDC C and D major hurdle on ABC use in high seismic zones

1 1 1 1 ---- Extreme Load Consideration Extreme Load Consideration Extreme Load Consideration Extreme Load Consideration for for for for

Bridges and ABC Bridges and ABC Bridges and ABC Bridges and ABC Connections (Contd) Connections (Contd) Connections (Contd) Connections (Contd)

FHWA funded study to develop MH design guidelines for bridges in progress at U. of Buffalo - not specific to ABC.

AASHTO LRFD framework is used as a platform to develop MH LRFD

Examples of current MH load combination used in practice: Combined seismic and scour loads Wave action, wind, anchorage breakage, and vessel

collision for floating bridge Advanced materials should allow for higher

performance levels than conventional bridges under MH loading

2 - ABC Connection Details

Many ABC connection types have been and continue to be developed

Several states use FHWA-HIF-12-013 (Nov. 2011): Accelerated Bridge Construction -Experience in Design, Fabrication and Erection of Prefabricated Bridge Elements and Systems.

2 - ABC Connection Details (Contd)

Superstructure connection examples: Unrestrained joints under lateral loads Unrestrained joints under uplift due to storm

surge Various concrete or grout mixes for closure pours

for partial or full depth precast decks CIP concrete at closure pours between precast

girders and at abutments. Continuous superstructure/approach slabs in

SPMT moves or slides

2 - ABC Connection Details (Contd)

Substructure connection examples :I. Precast column

embedded into drilled shaft, footing, or cap beam

2 - ABC Connection Details (Contd)

Substructure connection examples (Contd) :II. Grouted couplers embedded in precast column

or in pile shaft, footing, or cap beam

2 - ABC Connection Details (Contd)

Substructure connection examples (Contd) :III. Precast columns with extended bars inserted in

grouted metal sleeves

3- ABC Connection Maintenance

Insufficient history to make a call (if maintenance issues are different for ABC connections)

General perception: should not be different if ABC connections are emulative (verified by a few ABC projects built in the 1990s)

In one state ABC projects are inspected annually to address any issues and develop performance data base

3 - ABC Connection Maintenance (Contd)

Precautionary measures to avoid maintenance problems, e.g. greased and sheathed tendons, plastic ducts, post-tensioning of deck panels, etc.

Importance of grout quality, application, and consolidation is recognized.

Deck slabs post tensioned together States are aware of the need for inspection

and maintenance manuals when using unconventional materials and details.

4 - Standardization of ABC Connection

Details and Processes

Standard ABC connections: There is a strong push from stakeholders to

standardize ABC connections Philosophical differences: well-defined details vs.

versatile details

Standard decision making process for selecting ABC over conventional construction Consistent application of user costs

4 - Standardization of ABC Connection

Details and Processes (Contd)

Examples of manuals for standard details: PCI Northeast Several states utilizing FHWA 2011 ABC

report Manuals for each precast element type Manuals for SPMT moves List of preapproved grouted couplers

4 - Standardization of ABC Connection

Details and Processes (Contd)

Standard decision making process for selecting ABC over conventional construction

National effort: Oregon study Many states have or are developing their own

process User costs are generally included and can

help justify ABC Initial ABC cost may be higher because of

financial risk to contractors; could become lower over time because of saving in duration-dependent costs

5 - ABC Connection Research

On-going studies on high-early strength concrete for closure pours

Other ABC connection research focused on seismic performance

Seismic studies may serve as a guide for other extreme load studies

Two categories of seismic ABC connection research: emulative and non-emulative

5 - ABC Connection Research (Contd)

Successful emulative ABC connections Precast columns embedded into footings, piles, or

cap beams Large diameter column bars embedded in

corrugated metal ducts Various standard couplers Various methods to convert multi-girder pier cap

connections to integral pier caps

Research continues

5 - ABC Connection Research (Contd)

Successful non-emulative ABC connections Motivated by versatility of precast members Performance level exceeds conventional construction Post-tensioned segmental columns

5 - ABC Connection Research (Contd)

Successful non-emulative ABC connections (Contd) Energy dissipation with advanced materials and

details: e.g. shape memory alloys, HPC, built-in rubber, FRP wrapping, and concrete-filled steel and FRP tubes

Research continues

FRP Wrap Conc.-Filled FRP Tube Built-in Rubber

6 - Innovative ABC Connections

ABC is innovation in CONSTRUCTION Other innovation possible through ABC Innovative precast double-T precast girders Folded plate girders Concrete-filled tube arches Post-tensioned bridge decks, abutments, cap

beams Base isolation to simplify ABC connections FHWA-HFL good mechanism to bring

innovation to practice

7- Monitoring ABC Connections and

Prefabricated Bridge Elements

Done on a selected basis for non-emulative connections

May not be necessary for emulative ABC connections

Short-term monitoring common in SPMT moves

Frequent (annual, in addition to NBIS biennial) inspection of ABC bridges

8 - Other Findings

High enthusiasm and interest in ABC Key to success in ABC: COMMUNICATION

among top management, designers, contractors, fabricators, industry and public

Early involvement of contractors and fabricators in design and planning - design-build projects provide such an opportunity

Site casting has to be used when precast plants are remote

Shift of role: from CONSTRUCTION to INSTALLATION - contractors need to be open

8 - Other Findings (Contd)

Education and training needed for ABC connection design and inspection

ABC design manuals are being integrated into state bridge design manuals

Documenting ABC lessons is essential. Examples: Convert circular columns to octagonal shape to cast

on the side Avoid multi-segment columns unless necessary Transport issues of short heavy segment (load has to

be spread over many axles)

Recommendations

Continue research into MH load combinations and ABC connections. Initiate NCHRP project to synthesize this research, fill knowledge gaps and develop design procedures for AASHTO LRFD.

Establish a full time national center on ABC under MH as a central resource for collecting on-going research, detailing, construction and ABC performance both long term and after MH

Build on FHWA Everyday Counts vision to reach out to AGC, decision makers, and others to promote ABC

Recommendations (Contd)

Expand demonstration ABC projects through the FHWA IBRD program in areas with extreme event loads

Continue research on emulative ABC connections to facilitate ABC use in areas of high seismicity and other extreme events

Continue and expand research on ABC connections with advanced materials and details under MH loading

Collect and interpret field data of ABC connection performance. Explore integration of effort with FHWA LTBP

Implementation Actions

Seminars and webinars at venues attended by bridge engineers, contractors, suppliers, fabricators, etc., such as AASHTO SCOBS, TRB Annual Meeting and TRB conferences, and websites (FHWA, NCHRP 20-68, Florida IU ABC site)

Identify champions in relevant AASHTO Technical Committees and follow up on implementation of recommendations

Form an ABC user group to bring together various stakeholders

Express support for current FHWA MH loading studies to FHWA management

Implementation Actions (Contd)

Problem statement to develop Performance Based Design guidelines of emulative and non-emulative ABC connections

Garner support for a national center on ABC under MH loading

Technical articles summarizing the scan findings for publication in the TRB TR News and other industry journals

Coordinate with FHWA and others to help implement the scan recommendations