Effect of eccentric loading on fatigue cracking mode and characteristics of diaphragm-to-rib welded joints in steel bridge deck

Abstract

The non-uniformly distributed wheel loads in orthotropic bridge decks will cause its lower components to be eccentrically loaded. By conducting numerical simulation, field measurement and fatigue tests of diaphragm-to-rib welded joints (DU), the crack-growth characteristics under eccentric loading were analyzed and compared with that under symmetric loading, through which the warning crack length for maintenance and an evaluating method for crack-growth rates were proposed. The result demonstrates that the eccentrically loaded side (ES) of DU will crack ahead of non-eccentric side (NES) with a larger growth angle. The crack performs the same three-stage features of fast-slow-rapid growth under eccentric loading with demarcations of 27 mm and 70 mm, which are obviously larger than that under symmetric loading. The weld toe on NES will be particularly prone to fatigue cracking once the crack on ES enters the third rapid-growth stage. The new initiated crack on NES will own the same growth rate as ES. The demarcation 70 mm shall be taken as the warning length for crack maintenance to avoid cracking on the other side. It is appliable to evaluate the crack-growth rate of DU by Paris formula and the maximum stress intensity factor obtained by K_I and K_II of mixed mode cracks.

Keywords:

• Crack-growth stages
• diaphragm-to-rib welded joint
• eccentric loading
• fatigue crack
• fatigue damage
• orthotropic steel decks
• steel box girder
• warning length

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors gratefully acknowledge the support from the National Key Research and Development Program of China (No. 2017YFE0128700), the Fundamental Research Funds for the Central Universities (B230205037) and the Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX22_0616).