ABSTRACT
In this paper, a cold reinforcement method of casting Ultra-High Performance Fiber Reinforced Cementitious Composite Material (UHPFRC) is developed to maintenance the distortion-induced fatigue cracks in steel bridges. Numerical simulation is conducted on full-scale steel girder specimens to investigate the effectiveness of casting UHPFRC reinforcement method. The dimension and location of the initial crack in the finite element model are determined according to full-scale fatigue tests of vertical stiffeners web gaps. Numerical simulation results demonstrate that the stiffness of web gap region increases, and the out-of-plane distortion, the stress and stress intensity factor at the crack tip decrease dramatically after reinforcement. The parametric studies show that casting UHPFRC is effective in reducing the out-of-plane distortion and stress effectively, even if the dimension of crack increase. When the optimal UHPFRC dimension is adopted, the distortion-induced fatigue stress reached the lowest value. The effectiveness of casting UHPFRC reinforcement method is mainly realized by the restraint of the web and flange, therefore it is important to ensure that the height of UHPFRC is sufficient. Casting reinforcement technique dose not introduce secondary stress into the fatigue sensitive details. Moreover, the process of the reinforcement has no negative influence on the fatigue sensitive details of web gaps.
