Fatigue Retrofitting of Web Stiffeners in Steel Bridges Using Pultruded FRP Sections

A new retrofit method for the distortion-induced fatigue problem in steel bridges by using adhesively-bonded FRP angles is developed in this paper. This retrofit method is relatively cheap and easy to use and does not require deck removal or any other modification to the steel girder. The FRP retrofitted specimens are found to have significantly longer fatigue lives than as-welded specimens and specimens repaired by means of two other conventional repair methods. The hot-spot stress method is used to quantify the effectiveness of the proposed retrofit method. A coarse finite element (FE) analysis is used to predict the effectiveness of the proposed retrofit methods in terms of the reduction in the hot spot stress value, and analytically calculated hot-spot stresses are validated with directly measured values. The effects of a number of the varied geometrical and mechanical parameters on the efficiency of the proposed retrofit are then studied using an FE analysis and recommendations are made to improve the efficiency of this FRP-based retrofit method.