Form ProjStat
(Rev. 5/2013)
(RTI)
Research Project Statement 17-133
FY 2017 Annual Program
Title:
Allowable Limit Contraction Scour and Abutment Scour at Bridges (Deliverable Based)
The Problem:
Scour at bridges is one of the leading causes of bridge failures nationwide. Excessive scour can
cause high maintenance costs and bridge collapse; consequently, evaluating bridges for scour is
very important. Scour calculations are performed with the guidance provided in the Federal
Highway Administration manual Hydraulic Engineering Circular No. 18, “Evaluating Scour at
Bridges” (HEC 18). However, the results of the calculations only provide the maximum of the
scour components, but do not provide any indication of what the allowable limit is for a single
component of scour. For example, for new multi-span bridges, the embedment depth of the piers
would be designed sufficiently deep that pier scour would not be a problem. In contrast, when
analyzing existing structures for scour, a threshold or limit needs to be determined for when the
depth of scour reaches a critical stability point for the structure. This threshold, or limit for scour,
is typically called the maximum allowable limit for scour, and is different than the depth of the
calculated scour using HEC 18 equations, because it is the limiting value for the removal of
material before stability of the structure becomes a problem. For existing multi-span bridges, the
allowable limit for pier scour would be based on either critical embedment of the foundation
element or on the unsupported length of the column and foundation element. The Texas
Secondary Evaluation and Analysis for Scour (TSEAS) manual outlines how each of these are
determined for pier scour. For abutment and contraction scour for existing structures, there is no
maximum allowable limit on scour currently available for engineers to determine when stability of
the structure becomes a problem. This research is directed towards determining this limit. It is
expected that the maximum allowable limit for abutment scour and contraction scour will depend
upon the geotechnical stability of the embankment material of the header banks as scour
develops.
Technical
Objectives:
1. Review existing knowledge on the topic
2. Determine calculations associated with scenarios which would lead to failure of the highwaybridge system.
3. Analyze case histories involving limits of abutment and contraction scour.
4. Develop calculation procedures to answer the questions regarding maximum allowable limits
for abutment and contraction scour.
5. Provide recommendations on the baseis of 1, 2, 3 and 4 for maximum allowable limits for
abutment and contraction scour.
Desired
Deliverables:
1. Value of Research (VoR) that includes both qualitative and economic benefits.
2. Recommendations on the allowable limit for abutment scour and contraction scour.
3. Step by step procedures for calculating the allowable limit for abutment and/or contraction
scour.
4. Example calculations demonstrating the use of the equations developed.
5. Research report documenting work performed and results accomplished.
Proposal
Requirements:
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.
3. Proposals should be submitted in PDF format, 1 PDF file per proposal. File name should
include project name and university abbreviation.
Pre-Proposal
Meeting
Information:
Wednesday, March 23, 2016
10:30 – 11:00 AM
Austin Riverside Campus
118 E. Riverside Dr.
Project Statement 17-133
Form ProjStat
(Rev. 5/2013)
(RTI)
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
Notifying RTI of
Intent to
Propose:
Notify your University Liaison of your intent to submit a proposal. Your Liaison will provide
information regarding the RFP.
Proposal
Deadline:
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 17-133