Which option lists the three common causes of Distortion Induced Fatigue?

Which option lists the three common causes of Distortion Induced Fatigue?

• A. Corrosion around joints
• B. Web Gap Details, Skewed bridges and Lateral Bracing
• C. Wind load effects
• D. Web Gap Details

Answer: (D)

Distortion Induced Fatigue happens when geometric irregularities at details cause distortion of the member under cyclic loading, producing localized high alternating stresses that can initiate and grow cracks. The three factors most commonly cited as causes are web gap details, skewed bridges, and insufficient or poorly restrained lateral bracing. Web gap details create sharp discontinuities around the web gaps, leading to stress concentrations that drive distortion in the connection under service loads. Skewed bridges alter the load transfer paths and orientation of joints, causing distortion and out-of-plane movements that concentrate fatigue at the detail. Lateral bracing restrains the member from distorting; when bracing is inadequate, the distortion modes are amplified, increasing fatigue risk at connections. Taken together, these factors are the typical trio associated with DIF, whereas other issues like general corrosion or wind effects may influence fatigue but are not the primary distortion-induced causes in these details.

Distortion Induced Fatigue happens when geometric irregularities at details cause distortion of the member under cyclic loading, producing localized high alternating stresses that can initiate and grow cracks. The three factors most commonly cited as causes are web gap details, skewed bridges, and insufficient or poorly restrained lateral bracing. Web gap details create sharp discontinuities around the web gaps, leading to stress concentrations that drive distortion in the connection under service loads. Skewed bridges alter the load transfer paths and orientation of joints, causing distortion and out-of-plane movements that concentrate fatigue at the detail. Lateral bracing restrains the member from distorting; when bracing is inadequate, the distortion modes are amplified, increasing fatigue risk at connections. Taken together, these factors are the typical trio associated with DIF, whereas other issues like general corrosion or wind effects may influence fatigue but are not the primary distortion-induced causes in these details.