Small wind / Buyer questions
Structure and civil works
Can a tower that survives the maximum load still fail a fatigue assessment?
The short answer
Yes. Ultimate strength and fatigue assess different aspects of structural behavior. A tower can resist a single maximum action yet accumulate damaging stress cycles at a detail during repeated loading. Passing the extreme-load check therefore does not establish an acceptable fatigue assessment or a particular operating lifetime.
Compare the demands being evaluated
An ultimate check uses the relevant design load combinations and resistance. Fatigue assessment examines the range and repetition of stress at identified details, using a method appropriate to their geometry and material.
Many small cycles and fewer large cycles can contribute differently. The maximum stress alone does not describe that history, and equal peak loads do not guarantee equal cumulative demand.
Locate the detail that controls the comparison
Weld transitions, attachments, flange regions and anchor arrangements can have different local stress behavior. A nominal section stress may not represent the stress definition required by the chosen fatigue method.
A stronger steel grade can improve some static checks without proportionally improving the fatigue resistance of a welded detail. The connection geometry and cyclic stress range may remain controlling even when the gross material has ample strength.
Ask for a bounded fatigue basis
Request the loading history assumptions, relevant details, assessment method and uncertainty. If operating states or tower geometry change, evaluate whether the original fatigue basis still applies. Installation-stage vibration can also matter if it introduces substantial cycling before normal operation begins.
Do not infer remaining life from this FAQ or from the absence of a visible crack. Existing condition and any proposed modification need their own qualified assessment. The useful design outcome is satisfaction of both extreme and cyclic requirements for the defined support, rather than a marketing claim that surviving a storm proves a MARSTON tower’s service life.
Sources
Examples are illustrative. Confirm product-specific performance, compatibility and supply scope in the applicable documents.