ABSTRACT
Lots of fatigue crackings were reported at the upper end of vertical stiffeners connected to sway bracings and web gap plates under RC slab in steel highway girder bridges. In this study, we investigate fatigue cracking behavior, and propose a retrofitting method against fatigue cracking at the upper end of web gap plates under RC slab. In this method, TRS (Thread Rolling Screw) is used to attach angle steel to upper flange, and HTB (High Tension Bolt) is used to connect angle steels to web gap plate. The effectiveness of the method is investigated through fatigue tests using a beam specimen with the web gap detail of the same size as the actual bridge under alternative loading using two actuators. As a result, the method can reduce the local stress concentration at crack initiation points to about 50~60 %, and can extend fatigue crack initiation life more than 2~6 times and fatigue crack propagation life more than 100 times after grinding away fatigue cracks.
