CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING



AbstractFatigue failure of cantilevered highway sign structures has been recognized in many states due to sustained wind-loading events. AASHTO specifies that the structural component should be designed for infinite life by maintaining the wind-induced stress below their constant amplitude fatigue threshold (CAFT). However, for the existing structures that are typically not designed for fatigue, it is essential to evaluate the condition of all the critical and fatigue-prone components for safety considerations. The visual inspection consumes a lot of time and effort and may not detect unnoticed fatigue cracks. A need for analytical inspection tools to examine all the critical members and connections in terms of remaining fatigue life has received growing attention to ensure public safety. This paper introduces a simplified analytical inspection tool implemented into computer software to assess all the critical components according to AASHTO specifications for fatigue. A failed structure has been examined using this software, and the results showed a fatigue damage crack in the vertical weld of the mast-to-arm box connection at the upper chord level, reflecting the in-situ condition of the structure.



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