Research Project Statement 17-142
FY 2017 Annual Program
Form ProjStat
(Rev. 5/2013)
(RTI)
Title:
The Problem:
Technical
Objectives:
Desired
Deliverables:
Proposal
Requirements:
Fracture Critical Steel Twin Tub Girder Bridges (Deliverable Based)
Twin steel tub girder bridges are an aesthetically pleasing structural option, offering long span solutions in tight radii direct connectors. As a result, this structure type has become more common throughout the state. Each of these bridges requires a routine two-year inspection frequency, as well as a thorough hands-on inspection, because of their fracture critical designation. The heightened inspection requirements for fracture-critical bridges comes at a significant cost to the Texas Department of Transportation (TxDOT), with over $1 million for inspection costs and an additional $800,000 in traffic control costs every two years, as well as a cost to the traveling public by way of lane closures to facilitate the in-depth inspection. By removing the fracture critical designation of some or all of the twin tub girders, the inspection costs of these structures could be reduced by more than 75 percent.
Recent research has shown that tangent, or nearly tangent, twin steel tub girder sections can redistribute load to the intact girder after fracture of one of the girder bottom flanges. This research has shown that the internal redundancy, material properties, secondary members and non-structural components can contribute to the transfer of load to the intact girder. Additional research is required to develop recommendations for practical analysis of typical twin steel tub span configurations with the degree of curvature common to twin steel tub direct connectors.
Based on the findings of previous research, the researchers will develop more rigorous modeling and analysis methods beyond the simplified method described in that report. This should utilize software typically available to TxDOT and consultant bridge designers. These analysis and modeling methods will need to take into account the capacity of the fractured girder, especially at support locations, and realistically model the load distribution between the intact girder and the fractured girder. However, the modeling and analysis method should be straightforward enough to apply on a large scale to the inventory of steel tub bridges. The analysis method developed should meet the requirements outlined in the FHWA Memorandum, dated June 12, 2012,
"Clarification of Requirements for Fracture Critical Members" (HIBT-10) which is available online: https://www.fhwa.dot.gov/bridge/120620.cfm
.
1. Value of Research (VoR) that includes both qualitative and economic benefits.
2. A technical memorandum for each completed research task, a project summary report, and a final report.
3. A set of 10-15 design examples utilizing typical bridge design software available to TxDOT and Consultants which demonstrate whether or not collapse of the structure will occur with a fracture in each case. a. Three of the examples will include written step by step instructions of how to build the model in the applicable bridge design software. b. The 10-15 examples will be curved structures from the TxDOT inventory. Both single span and continuous curved multi-span units will be modeled, with the intent of providing a representative sampling of the curved twin tub girder structures in Texas. c. The distribution between the fractured and non-fractured girder will be modeled with reasonable accuracy. However the modeling method should be straightforward enough to repeat on a large scale basis. d. The models/design examples should be delivered in both PDF (and excel if applicable) and their native design file formats.
1. Utilize the deliverable based templates (see the appendices provided or in the University
Handbook).
2. Proposals will be considered non-responsive and will not be accepted for technical evaluation if they are not received by the deadline or do not meet the requirements stated in
RTI’s University Handbook.
Project Statement 17-142

Form ProjStat
(Rev. 5/2013)
(RTI)
Pre-Proposal
Meeting
Information:
Notifying RTI of
Intent to
Propose:
Proposal
Deadline:
3. Proposals should be submitted in PDF format, 1 PDF file per proposal. File name should include project name and university abbreviation.
Wednesday, March 23, 2016
10:30 – 11:00 AM
Austin Riverside Campus
118 E. Riverside Dr.
RTI Conference Room, 1st Floor
Webex Information:
1. Go to https://txdot.webex.com/mw0401lsp13/mywebex/default.do?siteurl=txdot&rnd=0.9091095085622
569
2. Meeting Number: 735 915 144
3. If requested, enter your name and email address.
4. If a password is required, enter the meeting password: FY17
5. Click "Join".
Teleconference Information:
Provide your phone number when you join the meeting to receive a call back. Alternatively, you can call:
Call-in toll-free number: 1-866-637-1408 (US)
Conference Code: 951 211 7290
Notify your University Liaison of your intent to submit a proposal. Your Liaison will provide information regarding the RFP.
Proposals are due to RTI by 4:00 P.M. Central Daylight Time , April 14, 2016 . Email submissions should be sent to rtimain@txdot.gov.
Project Statement 17-142