Fatigue cracking at the diaphragm cutout is one of the major diseases of orthotropic steel decks(OSDs).To investigate the influence of fatigue performance at this location and analyze the strengthening effect of the parameters of Carbon Fiber Reinforced Polymer composite materials,firstly,a segment model of the steel beam was established,and an initial crack was introduced at the maximum stress amplitude of the curved incision.Based on fracture mechanics theory,the cracking mode and fatigue life of the curved incision in the transverse diaphragm under fatigue load were obtained.Secondly,a strengthening model of CFRP plate was established,the reinforcement parameters were changed,and the change law of stress intensity factor in the process of crack propagation under different initial crack conditions was compared to explore the influence of CFRP plate length,width,thickness,elastic modulus and shear modulus of adhesive layer on the reinforcement effect.Finally,a recommended combination of reinforcement parameters was given.The results show that the fatigue crack is type I and the fatigue life is about 5.764 2 million times.CFRP reinforcement can effectively reduce the SIF range at crack tip,but there is a critical value for the length and width of CFRP plate.When the size is larger than this value,it has little influence on the reinforcement effect.The influence of the thickness of CFRP plate and the shear modulus of the adhesive layer on the reinforcement effect gradually decreases with the increase of the parameters.After reinforcement with CFRP plates with length×width×thickness of 45.0 mm×30.0 mm×2.0 mm and an elastic modulus of 460 GPa,cracks will no longer expand and the fatigue life will be significantly improved.
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