Experimental Study on U Rib-to-deck Welding Throat Fatigue Cracks Strengthened by Bonding Angle-shaped Steel

Abstract:

In order to study the repair effect of bonding angle-shaped steels on the welding throat fatigue crack of the U rib-to-deck in steel bridge decks， experimental and theoretical study was firstly carried out on the fatigue failure modes of concerned detail and the fatigue improvement after reinforcement. Then， the corresponding linear elastic fracture mechanics models were established based on Abaqus finite element software. The effects of different crack depths and initial dip angles on the crack propagation characteristics were investigated through the maximum circumferential stress criterion. On this basis， the strengthening effect of bonding angle-shaped steels on the fatigue details was verified. The results show that the out-of-plane bending deformation of the U-rib web is the controlling factor leading to fatigue cracking in the roof-U-rib welding throat. The fatigue crack is a composite fatigue crack dominated by type Ⅰ， and the equivalent stress intensity factor increases with the increase of crack depth， and reaches the maximum when the initial dip angle is close to 45°. The predicted crack propagation behavior is almost consistent with the experimental observations， and the angle between the propagation path and the top plate is between 30° and 45°. Compared with the un-strengthened specimens， the fatigue stress amplitude of the key measuring points of the corresponding cracked part is reduced by 90.5% after strengthening. Fatigue life can be significantly prolonged and the bonding layer is intact.

Key words:bridge engineering;steel bridge deck;welding throat crack;fatigue test;strengthening;fracture mechanics