Web Gap Details indicate which combination of issues and regulation?

• A. Gap left in stiffeners allowed for constrained induced fatigue and out of plane distortion
• B. Gap left in stiffeners allowed for constrained induced fatigue and out of plane distortion; 1985 mandated the connection of the flanges
• C. Fatigue was not related to web gaps; 1985 mandated improved flange connections
• D. Web gaps were eliminated; 1995 mandated flange alignment checks

Answer: (B)

Web gaps in stiffeners create a scenario where the web and flanges can move differently under repeated loads, concentrating stresses at the stiffener-web interface. This constrained movement fosters fatigue cracking and can cause the web to distort out of plane, altering the actual load path and potentially accelerating damage. The regulation enacted in 1985 addressed these problems by requiring the flanges to be connected, which reduces relative motion between members and improves load transfer, thereby mitigating both fatigue and out-of-plane distortion.

So, the option that describes a gap left in stiffeners allowing for constrained induced fatigue and out-of-plane distortion, paired with a 1985 mandate for flange connections, best captures the observed issue and its regulatory response. Other choices either misstate the relationship between web gaps and fatigue, or cite different regulatory actions or dates that don’t align with the historical performance and rule changes.