Inspecting Steel Bridges for Fatigue

INDOT Logo  Currently required by INDOT for complex and fracture-critical bridge inspection qualification.

Course brochure (Hosted at Purdue): Inspecting Steel Bridges for Fatigue (PDF)


When cracks are discovered on bridges in service, fatigue is usually the cause.  A working knowledge of fatigue susceptible details, AASHTO fatigue categorization, and NDE methods and limitations is essential to the proper inspection of both new and in-service steel structures.  

This course will focus on fatigue and fracture from the point of view of inspectors and fabricators.  Topics will be focused on steel highway and railroad bridges of all types.  Other topics will include: fatigue and fracture performance of steel bridges which have been damaged by impact and subsequently heat straightened; Constraint-Induced Fracture (“Hoan Details”) – identification and retrofit; and fabrication flaws will be presented. 

Special attention will be given to identifying details which are sensitive to fatigue, prioritizing details for inspection, and where to expect cracking.  In addition, NDT techniques such as UT, dye penetrant, and magnetic particle testing will be presented.  Guidance on when and why to select a specific type of NDT will also be discussed.  Effective and ineffective retrofit strategies for steel bridges will also be presented. 

The course will utilize several case studies for illustrative purposes and when hosted at Purdue University will include a hands-on practicum, as well.

This course is currently required by Indiana DOT for fracture-critical and complex bridge inspections.

Meet the Instructors

Robert Connor, PhD, is an associate professor of civil engineering at Purdue University and Director of the Steel Bridge Research, Inspection, Training, and Engineering (S-BRITE) Center.  Dr. Connor is nationally recognized as an expert in fatigue and fracture of steel bridges and sign structures.


Thomas Bradt is a Research Engineer at the Robert L. and Terry L. Bowen Laboratory for Large Scale Civil Engineering Research. Mr. Bradt has several years of steel and concrete fabrication and research experience.

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Jason B. Lloyd, PhD, PE, is Manager of Bridge & Infrastructure Solutions at Nucor Construction Solutions Services. Prior to working at Nucor he was an engineer for the NSBA. While working as an engineer at Purdue, he specialized in full-scale testing, field testing, fatigue evaluation, fracture, internal redundancy, and repair and retrofit of steel bridges.


Learning Objectives

• Be able to identify and prioritize critical fatigue prone details;

• Be able to recognize details susceptible to fatigue cracking due to secondary stresses and out-of-plane distortion. 

• Be able to recognize potential fatigue problems which may occur in special situations such as curved bridges, skewed bridges, anchor bolts and sign structures;

• Be able to recognize and understand issues arising during fabrication as related to material, fracture toughness, defects, shop/field repairs, mill scale, tack welds, etc.;

• Understand differences in redundant and non-redundant bridges;

• Be familiar with the most common forms of NDT;

• And identify details susceptible to constraint induced fracture (CIF)

Participants will receive hands-on experience in the inspection course implementing training received in the classroom.


Agenda for course inside the brochure