Research Activities: 2004

Structural Assessment of the I-70 Blanchette Bridge



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Sequential Number


Matching Research Agency

Missouri Department of Transportation


Principal Investigator

W.N. "Nick" Marianos
Research Assistant Professor
University of Missouri-Rolla
223 Engineering Research Laboratory
Rolla , Missouri, 65401

p(314) 497- 3221
f(573) 341- 6215

Student Involvement

One graduate student


Project Objectives

The scope of this project is the structural assessment of the I-70 Blanchette Bridge located over the Missouri River in St. Charles, Missouri.


Project Abstract

The Blanchette Bridge carries Interstate 70 across the Missouri River, connecting St. Louis and St. Charles counties. The bridge is a vital link in the national interstate system and the regional highway network, and is one of the most used structures in the MoDOT system, carrying over 180,000 vehicles per day (total). Any limitation of traffic on the bridge has major consequences for local and national transportation users, making the reliability of the structure critical. One of the stringers recently experienced a crack, apparently initiated at the top flange, in a section where tensile stresses of concern are not typically expected. The Missouri Department of Transportation (MoDOT) repaired the stringer by placing a splice over the crack. It is imperative however to identify the reasons why a crack formed at such location in order to prevent any similar occurrence.

The objectives of this research project can be summarized as follows:

  1. Identify the cause of the observed stringer cracking on the Blanchette Bridge;
  2. Identify other areas of the bridge, if any, that may be prone to similar cracking;
  3. Propose appropriate mitigation methods for prevention of further cracking;
  4. Suggest changes, if any, to design practice based on findings.

Anticipated Benefits

Based on the data gathered and on the analyses performed, the probable cause of the crack initiation and development will be investigated. If needed, refined analytical/numerical studies will also be performed. From the findings, the objectives are also a) to establish whether other stringers in the structure are at risk, and b) in such case, develop inspection and mitigation strategies to manage the risk. The results obtained from such study will be generalized to bridge having same characteristics.


Modal Orientation

Bridge Assessment



Project Start Date:
Project End Date:10/15/06

Relationship to other Research/Projects



Technology Transfer Activities

The following are the technology transfer activities for the current investigation:

  1. Technical Report showing findings, conclusions and recommendations;
  2. Technical papers for publication in Journals and Conferences;
  3. Powerpoint (or similar format) presentation on the problem and findings for MoDOT's internal use in training designers and inspectors.

Transportation Research Board Keywords

Crack Propagation, Fatigue and Thermal Loads, Structural Assessment, Inspection and Mitigation Strategies, Risk Management