FHWA Research And Technology Evaluation: Gusset Plates Final Report

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FOREWORD

The Federal Highway Administration (FHWA) Research and Technology Program strives to ensure transparency, accessibility, and responsiveness of RD&T for all stakeholders.

This report examines how FHWA’s investment in gusset plate research has affected the design and rating of gusset plates.

This report should be of interest to engineers, practitioners, researchers, and decision makers involved with the research, design, performance, and management of bridges.

Michael Trentacoste
Associate Administrator
Research, Development, and Technology (RD&T)

Technical Report Documentation Page

SI* (Modern Metric) Conversion Factors

Document Change History

Contents

1. Introduction

• 1.1 Evaluation Purpose
• 1.2 Project Background
• 1.3 Report Structure

2. Evaluation Design

• 2.1 Evaluation Scope and Feasibility
• 2.2 Evaluation Methodology
  • Evaluation Participants and Key Questions
  • Document Review

3. Evaluation Findings

• 3.1 Improved Specifications for the Design and Load Rating of Gusset Plates
• 3.2 Diffusion of Knowledge about Design and Load Rating of Gusset Plates

4. Recommendations

5. Conclusion

6. References

Appendix A The FHWA Infrastructure Program

• A.1 Office of Infrastructure Research and Development
• A.2 FHWA Office of Infrastructure
• A.3 Resource Center

Appendix B Stakeholder Interviews

Appendix C Documents Reviewed

Appendix D NTSB's Recommendations for FHWA

Appendix E Correspondence: NTSB and FHWA–Recommendation H-08-001

Appendix F FHWA Outreach Activities on Gusset Plates (2010–2013)

List of Figures

Figure 1. Example I-35 deck truss connection showing gusset plate and truss member it connects. (1)
Figure 2. Timeline of gusset plate research activities.
Figure 3. High-level logic model.
Figure 4. Flow diagram of project outputs by organization.

List of Tables

Table 1. Stakeholders
Table 2. General Questions for Stakeholder Interviews
Table 3. Most Important Documents from Review

Executive Summary

On August 1, 2007, the I–35W Mississippi River Bridge (I–35W Bridge) in Minneapolis, MN, collapsed. In the tragedy, 13 people were killed and 145 were injured.⁽¹⁾ The National Transportation Safety Board (NTSB) turned to the Federal Highway Administration (FHWA) to provide technical expertise during their investigation. In response, NTSB issued recommendations to FHWA and the American Association of State Transportation Officials (AASHTO) to prevent similar catastrophic bridge failures. An FHWA research project to assess the performance and design of steel gusset plate connections—referred to in this report as the Gusset Plate Project—facilitated actions that addressed one of the final NTSB recommendations. The main goal of the project was to improve bridge safety by providing research and guidance on gusset plates used to connect main load carrying members.

As part of the FHWA Research and Technology (R&T) program evaluation, FHWA decided to evaluate the Gusset Plate Project to better understand how FHWA’s investment in gusset plate research has affected the design and rating of gusset plates. This report documents the findings of a summative evaluation of the Gusset Plate Project. The report focuses on outcomes resulting from collaboration between FHWA and NTSB. Data collection for the evaluation relied primarily on telephone interviews with stakeholders, as well as document searches and reviews.

This evaluation focused on processes FHWA used to develop the National Cooperative Highway Research Program (NCHRP) Project 12-84 following the I–35W Bridge collapse, and the publication of NCHRP web-only document (WOD) 197.⁽²⁾ Strong relationships and a commitment to safety among FHWA, NTSB, and AASHTO are apparent in the timeline leading up to the publication of the final report and in discussions the evaluation team held with stakeholders. The evaluation found the following results from FHWA’s preliminary research on the performance and design of gusset plate connections:

• Provided vital support to NTSB to determine the cause of the I–35W Bridge collapse.
• Assisted NTSB’s process for choosing a final safety recommendation.
• Expedited research underlying NCHRP WOD 197.
• Informed updates to AASHTO specifications.

The Gusset Plate Project provided essential knowledge that led to the rapid development of national safety standards that will help protect Americans from other potential gusset plate bridge design failures.

List of Abbreviations and Acronyms