Fatigue performance of high-mast lighting poles was evaluated by experimental and analytical studies. The existing AASHTO specification for these structures, which is based on nominal stress and derived from the guidelines that are valid for predominantly in-plane stresses or membrane stresses, is often inadequate in designing these structures against service limit state of fatigue. Fatigue performance of the connections in the thin walled tubular structures are controlled by localized secondary bending stress, the magnitude of which depends on the relative stiffness of the connecting elements. Thirty three full size specimens with stiffened and un-stiffened socket and un-stiffened groove welded pole-to-base plate connections were fatigue tested to determine the fatigue performance of the connections in finite and infinite life regime. The research results demonstrated that with suitable combination of the geometric parameters, the constant amplitude fatigue threshold of these connections can exceed that of AASHTO fatigue category D for sections widely used in highway high level lighting structures.
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