This course provides the practicing engineer with the background required to understand and use the design rules for fatigue resistance that are currently a standard part of design codes for fabricated steel structures. Fatigue in metals is the process of initiation and growth of cracks under the action of repetitive tensile loading. If crack growth is allowed to go on long enough, failure of the member can result when the uncracked cross-section is sufficiently reduced such that the member can no longer carry the internal forces for the crack extends in an unstable mode. The fatigue process can take place at stress levels that are substantially less than those associated with failure under static loading conditions. The usual condition that produces fatigue cracking is the application of a large number of load cycles.

Topics:

• Overview and Historical Perspective
• Introduction to Crack Growth
• Flaws in Fabricated Steel Structures
• Load-Induced, Distortion-Induced Fatigue
• Stress Range as the Dominant Stress Parameter
• Examples of Distortion-Induced Fatigue Cracking
• Finite / Infinite Life Design
• Fracture Control
• AASHTO Provisions / Specifications Audience: This course is intended primarily for transportation, structural, civil, and mechanical engineers, and other engineering professionals who have a job description that may require a general knowledge of steel bridge design principles regarding fatigue in structural members.

Disclaimer: This course on Steel Bridge Design is based on FHWA non-restricted publications in the public domain, dating from 2015 to 2016. All subsequent versions of these courses have become proprietary under a "Rights Reserved" restriction by the AISC and are thus not available as public domain courseware. Design principles and methodologies used in this previous version remain relevant and up to date, as of late 2023. To view the latest versions, please visit the AISC download site at: https://www.aisc.org/nsba/design-and-estimation-resources/steel-bridge-design-handbook