Inhibiting Distortion-Induced Fatigue Damage in Steel Girders by Using FRP Angles

Abstract

The idea of retrofitting web stiffener ends in steel bridge girders susceptible to distortion-induced fatigue using adhesively bonded fiber-reinforced polymer (FRP) angles is introduced in this study. The proposed retrofit method is relatively cheap and easy to use and does not require deck removal or any other severe modification to the steel girder. Fatigue tests were conducted on specimens designed to model the conditions in the region between a web stiffener and a flange in a steel girder bridge. Fatigue life increases on the order of several hundred percent were achieved by implementing the proposed retrofit. The effect of the retrofit on the hot-spot stress in the critical weld detail can be seen in the experimental strain data and in a subsequent finite-element (FE) analysis of the tested specimen geometry. Further research is recommended to assess the performance of the retrofit on full-scale girders and to develop guidelines for fatigue verification and design of the FRP angle and adhesive. However, the presented research shows the potential of the proposed retrofit and the suitability of the hot-spot stress method for predicting its effectiveness.