aashto t-18 bridge management , evaluation and rehabilitation

AASHTO T‐18
BRIDGE MANAGEMENT ,
EVALUATION AND
REHABILITATION
Idaho Transportation Department
Matt Farrar

Introduction
• Matt Farrar
– State Bridge Engineer
– Responsibilities include
• Bridge Design and Construction Support
• Bridge Management, Planning and
Programming
– AASHTO SCOBS T‐18 Bridge Management,
Evaluation, and Rehabilitation‐ Chairman

T –18 Update
• What is T‐18
• AASHTO SCOBS
• Subcommittee on Bridges and Structures
• 20 Technical Committees
• T‐18 is the Technical Committee for Bridge
Management, Evaluation, and Rehabilitation
• T‐9 is the Technical Committee for Bridge
Preservation
• T‐14 is the Technical Committee for Steel
Bridges

T –18 Update (Continued)
• T‐18 Responsibilities
–Maintain and Update the Manual
for Bridge Evaluation (MBE)
–Maintain and Update the NEW
Manual for Bridge Element
Inspection

T –18 Update (Continued)

T –18 Update (Continued)
Manual for Bridge Evaluation

T –18 Update (Continued)
• Revised MBE SECTION 1 – INTRODUCTION
– Reorganization
– No Commentary
– “Provisions to support
the NBIS
Requirements”

T –18 Update (Continued)
Ballot Item ‐ Revisions to MBE Sections 1 Introduction
…The purpose of the Manual for Bridge Evaluation (MBE) is
to serve as a resource for use in developing specific policy
and procedures for the inspection and evaluation of existing
highway bridges.
…The MBE is incorporated by reference in the CFR (23 CFR
650 Subpart C)
… Throughout this Manual there are subsections titled in part
“ Provisions to support the NBIS Requirements”. These
subsections were developed to provide specific guidance and
best practices which are considered to be required under the
regulations.

T –18 Update (Continued)
Article 1.4.1- PROVISIONS TO SUPPORT THE NBIS REQURIEMENTS
A quality control and quality assurance (QC/QA) program is to
include periodic field review of inspection teams, periodic bridge
inspection refresher training for program managers and team leaders,
QC/QA measures for inventory data, and independent review of inspection
reports and computations. The bridge inspection Program Manager is
responsible to develop a QC/QA program that generally conforms to the
provisions of Section 1.4. Specific details are to be determined by the
Bridge Inspection Program Manager.

T –18 Update (Continued)
• Revised MBE SECTION 2 – BRIDGE FILES
(RECORDS)
– Reorganization
– No Commentary
– “Provisions to support
the NBIS Requirements”

T –18 Update (Continued)
Ballot Item ‐ Revisions to MBE Sections 2 ‐ Bridge Files
and Documentation
2.0—INTRODUCTION
… The bridge file provides information that directly relates to requirements of
the National Bridge Inspection Standards (Article 2.1) and other supplemental
information that bridge owners may find useful in managing bridges (Article
2.2).
2.1—PROVISIONS TO SUPPORT THE NBIS REQUIREMENTS
… Throughout this Manual there are subsections titled in part “Provisions to
support the NBIS Requirements”. These subsections were developed to
provide specific guidance and best practices which are considered to be
required under the regulations.

T –18 Update (Continued)
Ballot Item ‐ Revisions to MBE Sections 2 ‐ Bridge Files
and Documentation
2.1—PROVISIONS TO SUPPORT THE NBIS REQUIREMENTS
2.1.1 General File Information
2.1.2 Field Inspection Information
2.1.3 Critical Findings and Actions Taken
2.1.4 Waterway Information
2.1.5 Significant Correspondence
2.1.6 Other Inspection Procedures and Requirements
2.1.7 Load Rating Documentation
2.1.8 Posting Documentation
2.1.9 Scour Assessment
2.1.10 Scour Plan of Action

T –18 Update (Continued)
Ballot Item ‐ Revisions to MBE Sections 2 ‐ Bridge Files
and Documentation
2.2—SUPPLEMENTAL DOCUMENTATION IN BRIDGE FILE
2.2.1 General
2.2.2 Plans and Drawings
2.2.3 Construction Documentation
2.2.4 Original Design Documentation
2.2.5 Unique Considerations
2.2.6 Utilities and Attachments
2.2.7 Maintenance and Repair History
2.2.8 Additional Waterway Documentation
2.2.9 Traffic Data

T –18 Update (Continued)
• MBE SECTION 6 –LOAD RATING
– New Gusset Plate Rating Provisions
– New Gusset Plate Analysis Example

T –18 Update (Continued)
‣ New Gusset Plate Rating
Provisions
• Guidance on Section Loss due
to Corrosion
• Tension Members
• Reduced Net Area
• Compression Members
• Uniform and Localized
Corrosion
-1/2 inch
-1/4 inch
-1/4 inch
-1/2 inch
-3/4 inch

30°
T –18 Update (Continued)
‣ New Gusset Plate Rating Provisions
1. Revised variables for shear resistance, Ω (shear
reduction factor) and vy (resistance factor for shear
yeilding)
2. New provisions for compression resistance, revised
Whitmore Width derived from 30 degree angles and L mid
Whitmore Width
Lmid
30°

T –18 Update (Continued)
‣ New Gusset Plate Rating Provisions
3. New resistance factor for block shear
4. New tension and compression chord splice checks
5. Based on reliability of factor ß of 3.5 for Inventory
Rating and 2.5 for Operating Rating

T –18 Update (Continued)
‣ New Gusset Plate Rating Provisions
3. In general, FHWA has indicated re‐rating won’t be required
unless there is a change in condition or load.
4. Very compact gussets in compression may have less capacity,
although this aspect does not usually control truss capacity, in
my opinion.
5. May see increases in shear yielding and block shear rupture
capacities if FHWA guidance was followed

T –18 Update (Continued)
• Other 2013 Manual for
Bridge Evaluation Ballot
Items (…continued)
– Various ballot items to clarify
examples, application of
distribution factors and load
factors
– Ballot item to clarify
application of live load
factors on buried structures

T –18 Update (Continued)
Major Revisions and Updates to the AASHTO
Guide Manual for Bridge Element Inspection, 1 st
Edition

T –18 Update (Continued)
Why Update to the 1 st Edition of the AASHTO
Guide Manual for Bridge Element Inspection
• FHWA sponsored training classes “Introduction to
Element Level Bridge Inspection”
• Perhaps 5 agencies had begun to implement the new
elements
• Comments received have been incorporated into the
manual
• Legislation (MAP-21) mandates element level inspection
for NHS

T –18 Update (Continued)
AASHTO GUIDE FOR COMMONLY RECOGNIZED (CoRe)
STRUCTURAL ELEMENTS
• AASHTO has
Developed a Core
Elements to New
Elements Data
Migrator - FREE

T –18 Update (Continued)
Recap of AASHTO Guide Manual for Bridge Element
Inspection, 1 st Edition
• Four condition states for all elements.
– Follows –Good, Fair, Poor, Serious convention.
• Wearing surfaces separated from deck
element.
– Deck element units changed to square feet.
• Steel protective coatings separated from
steel.
• All smart flags have been incorporated into
condition state language.
• New elements for timber trestle and
framed/built up tower supports.

T –18 Update (Continued)
Element Types
‣National Bridge Elements (NBE’s)
• Represent the primary structural components of
bridges necessary to determine overall condition
and safety.
‣Bridge Management Elements (BME’s)
• Elements define secondary bridge components.
• Joints, wearing surfaces, protective coatings,etc.
‣Agency Developed Elements
• Supports agency developed elements.

AASHTO Guide Manual for Bridge Element Inspection, 1 st Ed
“Old Element Format”

New AASHTO Manual for Bridge Element Inspection
New Format – The condition state table for each element has been consolidated.
The result of this change is a cleaner and easier to read element description.
“Generic labels have been
added along with color
coding for the condition
state titles (Good, Fair,
Poor, Severe”
“The defect flags available
for any given element
have been expanded to
include all defined element
defects”

New AASHTO Manual for Bridge Element Inspection
Bridge Management Element
“Generic labels have been
added along with color
coding for the condition
state titles (Good, Fair,
Poor, Severe”
“The defect flags available
for any given element
have been expanded to
include all defined element
defects”

New AASHTO Manual for Bridge Element Inspection
A number of
“Other” Material
Elements have
been added to
capture new
materials and
unusual materials
(FRP, etc.)

New AASHTO Manual for Bridge Element Inspection
Updates of Appendix ,B, C & D
Appendix B – Inspection Examples
Appendix C – Element Groupings
Appendix D – Materials and Defects
“US Customary Units
Used Throughout”

New AASHTO Manual for Bridge Element Inspection
Appendix B –
Inspection Examples
Improved Examples
including Quantity
Bookkeeping

New AASHTO Manual for Bridge Element Inspection
Updates of Appendix A,B, C & DDefect Flags Expanded
“Defect Flags available
for any given element
have been expanded to
include all defined
element defects.”

New AASHTO Manual for Bridge Element Inspection
Also in Appendix D -
“Compilation of all defects
by material type and
condition state
descriptions”

New AASHTO Manual for Bridge Element Inspection
New Elements Added “Prestressed Concrete Top Flange
“All prestressed bridge
girder top flanges where
traffic rides directly on the
structural element
regardless of the wearing
surface or protection
system used”

New AASHTO Manual for Bridge Element Inspection
1 st Edition Substructure Elements and Units
New Substructure
Elements and
Units

What’s in the future for the T‐18
– Revisions to Sec. 4
Inspection
– Revisions to Sec. 7 Fatigue
Evaluation
– NCHRP 12‐82 Reliability
Based Bridge Inspection
Methods
– NCHRP 20‐07 Complex
Bridge Inspection
Procedures
– NCHRP 20‐68 Advances in
Superload Permit Practices

Conclusion
Improvements to the Manual for Bridge
Evaluation (MBE) and Manual for Bridge
Element Inspection (MBEI) will continue so as
to be a more useful tools for bridge inspection
and load rating.